harmony 鸿蒙@ohos.data.preferences (User Preferences)

2022-08-09
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@ohos.data.preferences (User Preferences)

The Preferences module provides APIs for processing data in the form of key-value (KV) pairs, and supports persistence of the KV pairs when required, as well as modification and query of the data.

The key is of the string type, and the value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.

NOTE

The initial APIs of this module are supported since API version 9. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import data_preferences from '@ohos.data.preferences';

Constants

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Name	Type	Readable	Writable	Description
MAX_KEY_LENGTH	number	Yes	No	Maximum length of a key, which is 80 bytes.
MAX_VALUE_LENGTH	number	Yes	No	Maximum length of a value, which is 8192 bytes.

data_preferences.getPreferences

getPreferences(context: Context, name: string, callback: AsyncCallback<Preferences>): void

Obtains a Preferences instance. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.
callback	AsyncCallback<Preferences>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined and the Preferences instance obtained is returned. Otherwise, err is an error object.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base';

let context = featureAbility.getContext();
let preferences: data_preferences.Preferences|null = null;

try {
    data_preferences.getPreferences(context, 'myStore', (err: BusinessError, val: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        preferences = val;
        console.info("Succeeded in getting preferences.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base';
import window from '@ohos.window';

let preferences: data_preferences.Preferences|null = null;

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            data_preferences.getPreferences(this.context, 'myStore', (err: BusinessError, val: data_preferences.Preferences) => {
                if (err) {
                console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
                return;
                }
                preferences = val;
                console.info("Succeeded in getting preferences.");
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to get preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.getPreferences

getPreferences(context: Context, name: string): Promise<Preferences>

Obtains a Preferences instance. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.

Return value

Type	Description
Promise<Preferences>	Promise used to return the Preferences instance obtained.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();

let preferences: data_preferences.Preferences|null = null;
try {
    let promise = data_preferences.getPreferences(context, 'myStore');
    promise.then((object: data_preferences.Preferences) => {
        preferences = object;
        console.info("Succeeded in getting preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

let preferences: data_preferences.Preferences|null = null;

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let promise = data_preferences.getPreferences(this.context, 'myStore');
            promise.then((object: data_preferences.Preferences) => {
                preferences = object;
                console.info("Succeeded in getting preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to get preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.getPreferences¹⁰⁺

getPreferences(context: Context, options: Options, callback: AsyncCallback<Preferences>): void

Obtains a Preferences instance. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.
callback	AsyncCallback<Preferences>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined and the Preferences instance obtained is returned. Otherwise, err is an error object.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();
let preferences: data_preferences.Preferences|null = null;

try {
    let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
    data_preferences.getPreferences(context, options, (err: BusinessError, val: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        preferences = val;
        console.info("Succeeded in getting preferences.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

let preferences: data_preferences.Preferences|null = null;

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            data_preferences.getPreferences(this.context, options, (err: BusinessError, val: data_preferences.Preferences) => {
                if (err) {
                    console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
                    return;
                }
                preferences = val;
                console.info("Succeeded in getting preferences.");
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to get preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.getPreferences¹⁰⁺

getPreferences(context: Context, options: Options): Promise<Preferences>

Obtains a Preferences instance. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.

Return value

Type	Description
Promise<Preferences>	Promise used to return the Preferences instance obtained.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'
let context = featureAbility.getContext();

let preferences: data_preferences.Preferences|null = null;
try {
    let options: data_preferences.Options =  { name: 'myStore' };
    let promise = data_preferences.getPreferences(context, options);
    promise.then((object: data_preferences.Preferences) => {
        preferences = object;
        console.info("Succeeded in getting preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

let preferences: data_preferences.Preferences|null = null;

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options =  { name: 'myStore', dataGroupId:'myId' };
            let promise = data_preferences.getPreferences(this.context, options);
            promise.then((object: data_preferences.Preferences) => {
                preferences = object;
                console.info("Succeeded in getting preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to get preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.getPreferencesSync¹⁰⁺

getPreferencesSync(context: Context, options: Options): Preferences

Obtains the Preferences instance. This API is a synchronous interface.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.

Return value

Type	Description
Preferences	Preferences instance obtained.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();
let preferences: data_preferences.Preferences|null = null;

try {
    let options: data_preferences.Options =  { name: 'myStore' };
    preferences = data_preferences.getPreferencesSync(context, options);
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

let preferences: data_preferences.Preferences|null = null;

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            preferences = data_preferences.getPreferencesSync(this.context, options);
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to get preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.deletePreferences

deletePreferences(context: Context, name: string, callback: AsyncCallback<void>): void

Deletes a Preferences instance from the cache. If the Preferences instance has a persistent file, the persistent file will also be deleted. This API uses an asynchronous callback to return the result.

After the Preferences instance is deleted, do not use it to perform data operations. Otherwise, data inconsistency may be caused. For this purpose, set the deleted Preferences instance to null. The system will reclaim the deleted Preferences instances in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15500010	Failed to delete preferences file.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();

try {
    data_preferences.deletePreferences(context, 'myStore', (err: BusinessError) => {
        if (err) {
            console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Succeeded in deleting preferences." );
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            data_preferences.deletePreferences(this.context, 'myStore', (err: BusinessError) => {
                if (err) {
                    console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
                    return;
                }
                console.info("Succeeded in deleting preferences." );
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to delete preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.deletePreferences

deletePreferences(context: Context, name: string): Promise<void>

Deletes a Preferences instance from the cache. If the Preferences instance has a persistent file, the persistent file will also be deleted. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15500010	Failed to delete preferences file.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();

try {
    let promise = data_preferences.deletePreferences(context, 'myStore');
    promise.then(() => {
        console.info("Succeeded in deleting preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try{
            let promise = data_preferences.deletePreferences(this.context, 'myStore');
            promise.then(() => {
                console.info("Succeeded in deleting preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to delete preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.deletePreferences¹⁰⁺

deletePreferences(context: Context, options: Options, callback: AsyncCallback<void>): void

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15500010	Failed to delete preferences file.
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();

try {
    let options: data_preferences.Options = { name: 'myStore' };
    data_preferences.deletePreferences(context, options, (err: BusinessError) => {
        if (err) {
            console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Succeeded in deleting preferences." );
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            data_preferences.deletePreferences(this.context, options, (err: BusinessError) => {
                if (err) {
                    console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
                    return;
                }
                console.info("Succeeded in deleting preferences." );
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to delete preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.deletePreferences¹⁰⁺

deletePreferences(context: Context, options: Options): Promise<void>

Deletes a Preferences instance from the cache. If the Preferences instance has a persistent file, the persistent file will also be deleted. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15500010	Failed to delete preferences file.
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();

try {
    let options: data_preferences.Options = { name: 'myStore' };
    let promise = data_preferences.deletePreferences(context, options);
    promise.then(() => {
        console.info("Succeeded in deleting preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try{
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            let promise = data_preferences.deletePreferences(this.context, options);
            promise.then(() => {
                console.info("Succeeded in deleting preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to delete preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to delete preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCache

removePreferencesFromCache(context: Context, name: string, callback: AsyncCallback<void>): void

Removes a Preferences instance from the cache. This API uses an asynchronous callback to return the result.

After an application calls getPreferences for the first time to obtain a Preferences instance, the obtained Preferences instance is cached. When the application calls getPreferences again, the Preferences instance will be read from the cache instead of from the persistent file. After this API is called to remove the instance from the cache, calling getPreferences again will read data from the persistent file and create a new Preferences instance.

After the Preferences instance is removed, do not use it to perform data operations. Otherwise, data inconsistency may be caused. For this purpose, set the removed Preferences instance to null. The system will reclaim the removed Preferences instances in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();
try {
    data_preferences.removePreferencesFromCache(context, 'myStore', (err: BusinessError) => {
        if (err) {
            console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Succeeded in removing preferences.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            data_preferences.removePreferencesFromCache(this.context, 'myStore', (err: BusinessError) => {
                if (err) {
                    console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
                    return;
                }
                console.info("Succeeded in removing preferences.");
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCache

removePreferencesFromCache(context: Context, name: string): Promise<void>

Removes a Preferences instance from the cache. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'

let context = featureAbility.getContext();
try {
    let promise = data_preferences.removePreferencesFromCache(context, 'myStore');
    promise.then(() => {
        console.info("Succeeded in removing preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let promise = data_preferences.removePreferencesFromCache(this.context, 'myStore');
            promise.then(() => {
                console.info("Succeeded in removing preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCacheSync¹⁰⁺

removePreferencesFromCacheSync(context: Context, name: string): void

Removes a Preferences instance from the cache. This API returns the result synchronously.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
name	string	Yes	Name of the Preferences instance.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'
let context = featureAbility.getContext();
try {
    data_preferences.removePreferencesFromCacheSync(context, 'myStore');
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            data_preferences.removePreferencesFromCacheSync(this.context, 'myStore');
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCache¹⁰⁺

removePreferencesFromCache(context: Context, options: Options, callback: AsyncCallback<void>): void

Removes a Preferences instance from the cache. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'
let context = featureAbility.getContext();
try {
    let options: data_preferences.Options = { name: 'myStore' };
    data_preferences.removePreferencesFromCache(context, options, (err: BusinessError) => {
        if (err) {
            console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Succeeded in removing preferences.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            data_preferences.removePreferencesFromCache(this.context, options, (err: BusinessError) => {
                if (err) {
                    console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
                    return;
                }
                console.info("Succeeded in removing preferences.");
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCache¹⁰⁺

removePreferencesFromCache(context: Context, options: Options): Promise<void>

Removes a Preferences instance from the cache. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base'
let context = featureAbility.getContext();
try {
    let options: data_preferences.Options = { name: 'myStore' };
    let promise = data_preferences.removePreferencesFromCache(context, options);
    promise.then(() => {
        console.info("Succeeded in removing preferences.");
    }).catch((err: BusinessError) => {
        console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base'
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            let promise = data_preferences.removePreferencesFromCache(this.context, options);
            promise.then(() => {
                console.info("Succeeded in removing preferences.");
            }).catch((err: BusinessError) => {
                console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
            })
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

data_preferences.removePreferencesFromCacheSync¹⁰⁺

removePreferencesFromCacheSync(context: Context, options: Options):void

Removes a Preferences instance from the cache. This API returns the result synchronously.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
context	Context	Yes	Application context. For details about the application context of the FA model, see Context. For details about the application context of the stage model, see Context.
options	Options	Yes	Configuration options of the Preferences instance.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15501001	Only supported in stage mode.
15501002	The data group id is not valid.

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
let context = featureAbility.getContext();
try {
    let options: data_preferences.Options = { name: 'myStore' };
    data_preferences.removePreferencesFromCacheSync(context, options);
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to remove preferences. code =" + code + ", message =" + message);
}

Stage model:

import UIAbility from '@ohos.app.ability.UIAbility';
import window from '@ohos.window';

class EntryAbility extends UIAbility {
    onWindowStageCreate(windowStage: window.WindowStage) {
        try {
            let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
            data_preferences.removePreferencesFromCacheSync(this.context, options);
        } catch (err) {
            let code = (err as BusinessError).code;
            let message = (err as BusinessError).message;
            console.error("Failed to remove preferences. code =" + code + ", message =" + message);
        }
    }
}

Options¹⁰⁺

Represents the configuration options of a Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Name	Type	Mandatory	Description
name	string	Yes	Name of the Preferences instance.
dataGroupId	string	No	Application group ID, which needs to be obtained from the AppGallery. Model restriction: This attribute can be used only in the stage model. This parameter is supported since API version 10. It specifies the Preferences instance created in the sandbox directory corresponding to the dataGroupId. If this parameter is not specified, the Preferences instance is created in the sandbox directory of the application.

Preferences

Provides APIs for obtaining and modifying the stored data.

Before calling any method of Preferences, you must obtain a Preferences instance by using data_preferences.getPreferences.

get

get(key: string, defValue: ValueType, callback: AsyncCallback<ValueType>): void

Obtains the value corresponding to the specified key from the cached Preferences instance. This API uses an asynchronous callback to return the result. If the value is null or is not of the default value type, defValue is returned.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to obtain. It cannot be empty.
defValue	ValueType	Yes	Default value to be returned. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.
callback	AsyncCallback<ValueType>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined and data is the value obtained. Otherwise, err is an error object.

Example

try {
    preferences.get('startup', 'default', (err: BusinessError, val: data_preferences.ValueType) => {
        if (err) {
            console.error("Failed to get value of 'startup'. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Obtained the value of 'startup' successfully. val: " + val);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get value of 'startup'. code =" + code + ", message =" + message);
}

get

get(key: string, defValue: ValueType): Promise<ValueType>

Obtains the value corresponding to the specified key from the cached Preferences instance. This API uses a promise to return the result. If the value is null or is not of the default value type, defValue is returned.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to obtain. It cannot be empty.
defValue	ValueType	Yes	Default value to be returned. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.

Return value

Type	Description
Promise<ValueType>	Promise used to return the value obtained.

Example

try {
    let promise = preferences.get('startup', 'default');
    promise.then((data: data_preferences.ValueType) => {
        console.info("Got the value of 'startup'. Data: " + data);
    }).catch((err: BusinessError) => {
        console.error("Failed to get value of 'startup'. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get value of 'startup'. code =" + code + ", message =" + message);
}

getSync¹⁰⁺

getSync(key: string, defValue: ValueType): ValueType

Obtains the value corresponding to the specified key from the cached Preferences instance. This API returns the result synchronously. If the value is null or is not of the default value type, defValue is returned.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to obtain. It cannot be empty.
defValue	ValueType	Yes	Default value to be returned. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.

Return value

Type	Description
ValueType	Returns the value obtained.

Example

try {
    let value: data_preferences.ValueType = preferences.getSync('startup', 'default');
    console.info("Succeeded in getting value of 'startup'. Data: " + value);
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get value of 'startup'. code =" + code + ", message =" + message);
}

getAll

getAll(callback: AsyncCallback<Object>): void;

Obtains all KV pairs from the cached Preferences instance. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<Object>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined and value provides all KV pairs obtained. Otherwise, err is an error object.

Example

// There is no Object.keys in ArkTS, and the for..in... syntax cannot be used.
// If an error is reported, extract this API to a .ts file and expose it. Then import the API to the .ets file when required.
function getObjKeys(obj: Object): string[] {
  let keys = Object.keys(obj);
  return keys;
}

try {
    preferences.getAll((err: BusinessError, value: Object) => {
        if (err) {
            console.error("Failed to get all key-values. code =" + err.code + ", message =" + err.message);
            return;
        }
        let allKeys = getObjKeys(value);
        console.info("getAll keys = " + allKeys);
        console.info("getAll object = " + JSON.stringify(value));
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get all key-values. code =" + code + ", message =" + message);
}

getAll

getAll(): Promise<Object>

Obtains all KV pairs from the cached Preferences instance. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Type	Description
Promise<Object>	Promise used to return the KV pairs obtained.

Example

// There is no Object.keys in ArkTS, and the for..in... syntax cannot be used.
// If an error is reported, extract this API to a .ts file and expose it. Then import the API to the .ets file when required.
function getObjKeys(obj: Object): string[] {
  let keys = Object.keys(obj);
  return keys;
}

try {
    let promise = preferences.getAll();
    promise.then((value: Object) => {
        let allKeys = getObjKeys(value);
        console.info('getAll keys = ' + allKeys);
        console.info("getAll object = " + JSON.stringify(value));
    }).catch((err: BusinessError) => {
        console.error("Failed to get all key-values. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get all key-values. code =" + code + ", message =" + message);
}

getAllSync¹⁰⁺

getAllSync(): Object

Obtains all KV pairs from the cached Preferences instance. This API returns the result synchronously.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Type	Description
Object	Returns all KV pairs obtained.

Example

// There is no Object.keys in ArkTS, and the for..in... syntax cannot be used.
// If an error is reported, extract this API to a .ts file and expose it. Then import the API to the .ets file when required.
function getObjKeys(obj: Object): string[] {
  let keys = Object.keys(obj);
  return keys;
}

try {
    let value = preferences.getAllSync();
    let allKeys = getObjKeys(value);
    console.info('getAll keys = ' + allKeys);
    console.info("getAll object = " + JSON.stringify(value));
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to get all key-values. code =" + code + ", message =" + message);
}

put

put(key: string, value: ValueType, callback: AsyncCallback<void>): void

Writes data to the cached Preferences instance. This API uses an asynchronous callback to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data. It cannot be empty.
value	ValueType	Yes	Value to write. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If data is written successfully, err is undefined. Otherwise, err is an error object.

Example

try {
    preferences.put('startup', 'auto', (err: BusinessError) => {
        if (err) {
            console.error("Failed to put value of 'startup'. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Successfully put the value of 'startup'.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to put value of 'startup'. code =" + code + ", message =" + message);
}

put

put(key: string, value: ValueType): Promise<void>

Writes data to the cached Preferences instance. This API uses a promise to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data. It cannot be empty.
value	ValueType	Yes	Value to write. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

try {
    let promise = preferences.put('startup', 'auto');
    promise.then(() => {
        console.info("Successfully put the value of 'startup'.");
    }).catch((err: BusinessError) => {
        console.error("Failed to put value of 'startup'. code =" + err.code +", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to put value of 'startup'. code =" + code +", message =" + message);
}

putSync¹⁰⁺

putSync(key: string, value: ValueType): void

Writes data to the cached Preferences instance. This API returns the result synchronously. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data. It cannot be empty.
value	ValueType	Yes	Value to write. The value can be a number, a string, a Boolean value, or an array of numbers, strings, or Boolean values.

Example

try {
    preferences.putSync('startup', 'auto');
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to put value of 'startup'. code =" + code +", message =" + message);
}

has

has(key: string, callback: AsyncCallback<boolean>): void

Checks whether the cached Preferences instance contains the KV pair of the given key. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to check. It cannot be empty.
callback	AsyncCallback<boolean>	Yes	Callback invoked to return the result. If the Preferences instance contains the KV pair, true will be returned. Otherwise, false will be returned.

Example

try {
    preferences.has('startup', (err: BusinessError, val: boolean) => {
        if (err) {
            console.error("Failed to check the key 'startup'. code =" + err.code + ", message =" + err.message);
            return;
        }
        if (val) {
            console.info("The key 'startup' is contained.");
        } else {
            console.info("The key 'startup' is not contained.");
        }
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to check the key 'startup'. code =" + code + ", message =" + message);
}

has

has(key: string): Promise<boolean>

Checks whether the cached Preferences instance contains the KV pair of the given key. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to check. It cannot be empty.

Return value

Type	Description
Promise<boolean>	Promise used to return the result. If the Preferences instance contains the KV pair, true will be returned. Otherwise, false will be returned.

Example

try {
    let promise = preferences.has('startup');
    promise.then((val: boolean) => {
        if (val) {
            console.info("The key 'startup' is contained.");
        } else {
            console.info("The key 'startup' is not contained.");
        }
    }).catch((err: BusinessError) => {
        console.error("Failed to check the key 'startup'. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to check the key 'startup'. code =" + code + ", message =" + message);
}

hasSync¹⁰⁺

hasSync(key: string): boolean

Checks whether the cached Preferences instance contains the KV pair of the given key. This API returns the result synchronously.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the data to check. It cannot be empty.

Return value

Type	Description
boolean	If the Preferences instance contains the KV pair, true will be returned. Otherwise, false will be returned.

Example

try {
    let isExist: boolean = preferences.hasSync('startup');
    if (isExist) {
        console.info("The key 'startup' is contained.");
    } else {
        console.info("The key 'startup' is not contained.");
    }
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to check the key 'startup'. code =" + code + ", message =" + message);
}

delete

delete(key: string, callback: AsyncCallback<void>): void

Deletes the KV pair from the cached Preferences instance based on the specified key. This API uses an asynchronous callback to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the KV pair to delete. It cannot be empty.
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Example

try {
    preferences.delete('startup', (err: BusinessError) => {
        if (err) {
            console.error("Failed to delete the key 'startup'. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Deleted the key 'startup'.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete the key 'startup'. code =" + code + ", message =" + message);
}

delete

delete(key: string): Promise<void>

Deletes a KV pair from the cached Preferences instance based on the specified key. This API uses a promise to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the KV pair to delete. It cannot be empty.

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

try {
    let promise = preferences.delete('startup');
    promise.then(() => {
        console.info("Deleted the key 'startup'.");
    }).catch((err: BusinessError) => {
        console.error("Failed to delete the key 'startup'. code =" + err.code +", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete the key 'startup'. code =" + code +", message =" + message);
}

deleteSync¹⁰⁺

deleteSync(key: string): void

Deletes a KV pair from the cached Preferences instance based on the specified key. This API returns the result synchronously. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
key	string	Yes	Key of the KV pair to delete. It cannot be empty.

Example

try {
    preferences.deleteSync('startup');
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to delete the key 'startup'. code =" + code +", message =" + message);
}

flush

flush(callback: AsyncCallback<void>): void

Flushes the data in the cached Preferences instance to the persistent file. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Example

try {
    preferences.flush((err: BusinessError) => {
        if (err) {
            console.error("Failed to flush. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Successfully flushed data.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

flush

flush(): Promise<void>

Flushes the data in the cached Preferences instance to the persistent file. This API uses a promise to return the result.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

try {
    let promise = preferences.flush();
    promise.then(() => {
        console.info("Successfully flushed data.");
    }).catch((err: BusinessError) => {
        console.error("Failed to flush. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

clear

clear(callback: AsyncCallback<void>): void

Clears all data in the cached Preferences instance. This API uses an asynchronous callback to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
callback	AsyncCallback<void>	Yes	Callback invoked to return the result. If the operation is successful, err is undefined. Otherwise, err is an error object.

Example

try {
    preferences.clear((err: BusinessError) =>{
        if (err) {
            console.error("Failed to clear. code =" + err.code + ", message =" + err.message);
            return;
        }
        console.info("Successfully cleared data.");
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to clear. code =" + code + ", message =" + message);
}

clear

clear(): Promise<void>

Clears all data in the cached Preferences instance. This API uses a promise to return the result. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Type	Description
Promise<void>	Promise that returns no value.

Example

try {
    let promise = preferences.clear();
    promise.then(() => {
        console.info("Successfully cleared data.");
    }).catch((err: BusinessError) => {
        console.error("Failed to clear. code =" + err.code + ", message =" + err.message);
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to clear. code =" + code + ", message =" + message);
}

clearSync¹⁰⁺

clearSync(): void

Clears all data in the cached Preferences instance. This API returns the result synchronously. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Example

try {
    preferences.clearSync();
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to clear. code =" + code + ", message =" + message);
}

on(‘change’)

on(type: ‘change’, callback: ( key : string ) => void): void

Subscribes to data changes. A callback will be triggered to return the new value if the value of the subscribed key is changed and flushed.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. The value is change, which indicates data changes.
callback	Function	Yes	Callback invoked to return the result. key indicates the key whose value is changed.

Example

try {
    data_preferences.getPreferences(this.context, 'myStore', (err: BusinessError, preferences: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences.");
            return;
        }
        preferences.on('change', (key: string) => {
            console.info("The key " + key + " changed.");
        });
        preferences.put('startup', 'manual', (err: BusinessError) => {
            if (err) {
            console.error("Failed to put the value of 'startup'. Cause: " + err);
            return;
            }
            console.info("Successfully put the value of 'startup'.");

            preferences.flush((err: BusinessError) => {
            if (err) {
                console.error("Failed to flush. Cause: " + err);
                return;
            }
            console.info("Successfully flushed data.");
            })
        })
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

on(‘multiProcessChange’)¹⁰⁺

on(type: ‘multiProcessChange’, callback: ( key : string ) => void): void

Subscribes to inter-process data changes. For the multiple processes holding the same preference file, if the value of the subscribed key changes in any process, the callback in this API will be invoked after flush() is executed.

This API can be used with removePreferencesFromCache to update the Preferences instance in the callback when detecting that a process updates a file. For details, see example 2.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. The value is multiProcessChange, which indicates data changes between multiple processes.
callback	Function	Yes	Callback invoked to return the result. key indicates the key whose value is changed.

Error codes

For details about the error codes, see User Preference Error Codes.

ID	Error Message
15500019	Failed to obtain subscription service.

Example 1

try {
    let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
    data_preferences.getPreferences(this.context, options, (err: BusinessError, preferences: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences.");
            return;
        }
        preferences.on('multiProcessChange', (key: string) => {
            console.info("The key " + key + " changed.");
        });
        preferences.put('startup', 'manual', (err: BusinessError) => {
            if (err) {
                console.error("Failed to put the value of 'startup'. Cause: " + err);
                return;
            }
            console.info("Successfully put the value of 'startup'.");
            preferences.flush((err: BusinessError) => {
                if (err) {
                    console.error("Failed to flush. Cause: " + err);
                    return;
                }
                console.info("Successfully flushed data.");
            })
        })
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

Example 2

try {
    let options: data_preferences.Options = { name: 'myStore' };
    data_preferences.getPreferences(this.context, options, (err: BusinessError, val: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences.");
            return;
        }
        preferences = val;
        preferences.on('multiProcessChange', (key: string) => {
            console.info("The key " + key + " changed.");
            try {
                data_preferences.removePreferencesFromCache(this.context, options, (err: BusinessError) => {
                    if (err) {
                        console.error("Failed to remove preferences. code =" + err.code + ", message =" + err.message);
                        return;
                    }
                    preferences = null;
                    console.info("Succeeded in removing preferences.");
                })
            } catch (err) {
                let code = (err as BusinessError).code;
                let message = (err as BusinessError).message;
                console.error("Failed to remove preferences. code =" + code + ", message =" + message);
            }

            try {
                data_preferences.getPreferences(this.context, options, (err: BusinessError, val: data_preferences.Preferences) => {
                    if (err) {
                        console.error("Failed to get preferences. code =" + err.code + ", message =" + err.message);
                        return;
                    }
                    preferences = val;
                    console.info("Succeeded in getting preferences.");
                })
            } catch (err) {
                let code = (err as BusinessError).code;
                let message = (err as BusinessError).message;
                console.error("Failed to get preferences. code =" + code + ", message =" + message);
            }
        });
        preferences.put('startup', 'manual', (err: BusinessError) => {
            if (err) {
                console.error("Failed to put the value of 'startup'. Cause: " + err);
                return;
            }
            console.info("Successfully put the value of 'startup'.");

            if (preferences != null) {
                preferences.flush((err: BusinessError) => {
                    if (err) {
                        console.error("Failed to flush. Cause: " + err);
                        return;
                    }
                    console.info("Successfully flushed data.");
                })
            }
        })
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

off(‘change’)

off(type: ‘change’, callback?: ( key : string ) => void): void

Unsubscribes from data changes.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. The value is change, which indicates data changes.
callback	Function	No	Callback to unregister. If this parameter is left blank, all callbacks for data changes will be unregistered. key indicates the key whose value is changed.

Example


try {
    data_preferences.getPreferences(this.context, 'myStore', (err: BusinessError, preferences: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences.");
            return;
        }
        preferences.on('change', (key: string) => {
            console.info("The key " + key + " changed.");
        });
        preferences.put('startup', 'auto', (err: BusinessError) => {
            if (err) {
                console.error("Failed to put the value of 'startup'. Cause: " + err);
                return;
            }
            console.info("Successfully put the value of 'startup'.");

            preferences.flush((err: BusinessError) =>{
                if (err) {
                    console.error("Failed to flush. Cause: " + err);
                    return;
                }
                console.info("Successfully flushed data.");
            })
            preferences.off('change', (key: string) => {
                console.info("The key " + key + " changed.");
            });
        })
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

off(‘multiProcessChange’)¹⁰⁺

off(type: ‘multiProcessChange’, callback?: ( key : string ) => void): void

Unsubscribes from inter-process data changes.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type. The value is multiProcessChange, which indicates data changes between multiple processes.
callback	Function	No	Callback to unregister. If this parameter is left blank, all callbacks for multiProcessChange will be unregistered. key indicates the key whose value is changed.

Example

try {
    let options: data_preferences.Options = { name: 'myStore', dataGroupId:'myId' };
    data_preferences.getPreferences(this.context, options, (err: BusinessError, preferences: data_preferences.Preferences) => {
        if (err) {
            console.error("Failed to get preferences.");
            return;
        }
        preferences.on('multiProcessChange', (key: string) => {
            console.info("The key " + key + " changed.");
        });
        preferences.put('startup', 'auto', (err: BusinessError) => {
            if (err) {
                console.error("Failed to put the value of 'startup'. Cause: " + err);
                return;
            }
            console.info("Successfully put the value of 'startup'.");

            preferences.flush((err: BusinessError) => {
                if (err) {
                    console.error("Failed to flush. Cause: " + err);
                    return;
                }
                console.info("Successfully flushed data.");
            })
            preferences.off('multiProcessChange', (key: string) => {
                console.info("The key " + key + " changed.");
            });
        })
    })
} catch (err) {
    let code = (err as BusinessError).code;
    let message = (err as BusinessError).message;
    console.error("Failed to flush. code =" + code + ", message =" + message);
}

ValueType

Enumerates the value types.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Type	Description
number	The value is a number.
string	The value is a string.
boolean	The value is of Boolean type.
Array<number>	The value is an array of numbers.
Array<boolean>	The value is a Boolean array.
Array<string>	The value is an array of strings.

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harmony 鸿蒙@ohos.data.preferences (User Preferences)

@ohos.data.preferences (User Preferences)

Modules to Import

Constants

data_preferences.getPreferences

data_preferences.getPreferences

data_preferences.getPreferences10+

data_preferences.getPreferences10+

data_preferences.getPreferencesSync10+

data_preferences.deletePreferences

data_preferences.deletePreferences

data_preferences.deletePreferences10+

data_preferences.deletePreferences10+

data_preferences.removePreferencesFromCache

data_preferences.removePreferencesFromCache

data_preferences.removePreferencesFromCacheSync10+

data_preferences.removePreferencesFromCache10+

data_preferences.removePreferencesFromCache10+

data_preferences.removePreferencesFromCacheSync10+

Options10+

Preferences

get

get

getSync10+

getAll

getAll

getAllSync10+

put

put

putSync10+

has

has

hasSync10+

delete

delete

deleteSync10+

flush

flush

clear

clear

clearSync10+

on(‘change’)

on(‘multiProcessChange’)10+

off(‘change’)

off(‘multiProcessChange’)10+

ValueType

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本文目录

data_preferences.getPreferences¹⁰⁺

data_preferences.getPreferences¹⁰⁺

data_preferences.getPreferencesSync¹⁰⁺

data_preferences.deletePreferences¹⁰⁺

data_preferences.deletePreferences¹⁰⁺

data_preferences.removePreferencesFromCacheSync¹⁰⁺

data_preferences.removePreferencesFromCache¹⁰⁺

data_preferences.removePreferencesFromCache¹⁰⁺

data_preferences.removePreferencesFromCacheSync¹⁰⁺

Options¹⁰⁺

getSync¹⁰⁺

getAllSync¹⁰⁺

putSync¹⁰⁺

hasSync¹⁰⁺

deleteSync¹⁰⁺

clearSync¹⁰⁺

on(‘multiProcessChange’)¹⁰⁺

off(‘multiProcessChange’)¹⁰⁺