@ohos.data.preferences (User Preferences)

The Preferences module provides APIs for processing data in the form of key-value (KV) pairs, including querying, modifying, and persisting KV pairs.

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 dataPreferences from '@ohos.data.preferences';

Constants

System capability: SystemCapability.DistributedDataManager.Preferences.Core

dataPreferences.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

Example

FA model:

import featureAbility from '@ohos.ability.featureAbility';
import { BusinessError } from '@ohos.base';

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

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

Stage model:

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

let preferences: dataPreferences.Preferences | null = null;

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

dataPreferences.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

Return value

Example

FA model:

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

let context = featureAbility.getContext();

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

Stage model:

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

let preferences: dataPreferences.Preferences | null = null;

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

dataPreferences.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

Error codes

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

Example

FA model:

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

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

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

Stage model:

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

let preferences: dataPreferences.Preferences | null = null;

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

dataPreferences.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

Return value

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();

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

Stage model:

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

let preferences: dataPreferences.Preferences | null = null;

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

dataPreferences.getPreferencesSync¹⁰⁺

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

Obtains a Preferences instance. This API returns the result synchronously.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Error codes

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

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';

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

let options: dataPreferences.Options = { name: 'myStore' };
preferences = dataPreferences.getPreferencesSync(context, options);

Stage model:

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

let preferences: dataPreferences.Preferences | null = null;

class EntryAbility extends UIAbility {
  onWindowStageCreate(windowStage: window.WindowStage) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    preferences = dataPreferences.getPreferencesSync(this.context, options);
  }
}

dataPreferences.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.

Avoid using a deleted Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the deleted Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();

dataPreferences.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.");
})

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) {
    dataPreferences.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.");
    })
  }
}

dataPreferences.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.

Avoid using a deleted Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the deleted Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();

let promise = dataPreferences.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);
})

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) {
    let promise = dataPreferences.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);
    })
  }
}

dataPreferences.deletePreferences¹⁰⁺

deletePreferences(context: Context, options: Options, 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.

Avoid using a deleted Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the deleted Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();

let options: dataPreferences.Options = { name: 'myStore' };
dataPreferences.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.");
})

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) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    dataPreferences.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.");
    })
  }
}

dataPreferences.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.

Avoid using a deleted Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the deleted Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();

let options: dataPreferences.Options = { name: 'myStore' };
let promise = dataPreferences.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);
})

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) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    let promise = dataPreferences.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);
    })
  }
}

dataPreferences.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.

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

FA model:

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

let context = featureAbility.getContext();
dataPreferences.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.");
})

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) {
    dataPreferences.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.");
    })
  }
}

dataPreferences.removePreferencesFromCache

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

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

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Example

FA model:

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

let context = featureAbility.getContext();
let promise = dataPreferences.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);
})

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) {
    let promise = dataPreferences.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);
    })
  }
}

dataPreferences.removePreferencesFromCacheSync¹⁰⁺

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

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

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.

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
let context = featureAbility.getContext();
dataPreferences.removePreferencesFromCacheSync(context, 'myStore');

Stage model:

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

class EntryAbility extends UIAbility {
  onWindowStageCreate(windowStage: window.WindowStage) {
    dataPreferences.removePreferencesFromCacheSync(this.context, 'myStore');
  }
}

dataPreferences.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.

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.

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();
let options: dataPreferences.Options = { name: 'myStore' };
dataPreferences.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.");
})

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) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    dataPreferences.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.");
    })
  }
}

dataPreferences.removePreferencesFromCache¹⁰⁺

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

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

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Error codes

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

Example

FA model:

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

let context = featureAbility.getContext();
let options: dataPreferences.Options = { name: 'myStore' };
let promise = dataPreferences.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);
})

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) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    let promise = dataPreferences.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);
    })
  }
}

dataPreferences.removePreferencesFromCacheSync¹⁰⁺

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

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

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.

Avoid using a removed Preferences instance to perform data operations, which may cause data inconsistency. Instead, set the removed Preferences instance to null. The system will reclaim them in a unified manner.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Error codes

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

Example

FA model:

// Obtain the context.
import featureAbility from '@ohos.ability.featureAbility';
let context = featureAbility.getContext();
let options: dataPreferences.Options = { name: 'myStore' };
dataPreferences.removePreferencesFromCacheSync(context, options);

Stage model:

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

class EntryAbility extends UIAbility {
  onWindowStageCreate(windowStage: window.WindowStage) {
    let options: dataPreferences.Options = { name: 'myStore', dataGroupId: 'myId' };
    dataPreferences.removePreferencesFromCacheSync(this.context, options);
  }
}

Options¹⁰⁺

Represents the configuration of a Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Preferences

Provides APIs for obtaining and modifying the stored data.

Before calling any API of Preferences, you must obtain a Preferences instance by using dataPreferences.getPreferences.

get

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

Obtains the value of a key from this 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

Example

import {BusinessError} from '@ohos.base';

preferences.get('startup', 'default', (err: BusinessError, val: dataPreferences.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);
})

get

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

Obtains the value of a key from this 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

Return value

Example

import {BusinessError} from '@ohos.base';

let promise = preferences.get('startup', 'default');
promise.then((data: dataPreferences.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);
})

getSync¹⁰⁺

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

Obtains the value of a key from this 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

Return value

Example

let value: dataPreferences.ValueType = preferences.getSync('startup', 'default');

getAll

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

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

import {BusinessError} from '@ohos.base';

// 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;
}

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));
})

getAll

getAll(): Promise<Object>

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Example

import {BusinessError} from '@ohos.base';

// 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;
}

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);
})

getAllSync¹⁰⁺

getAllSync(): Object

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

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;
}

let value = preferences.getAllSync();
let allKeys = getObjKeys(value);
console.info('getAll keys = ' + allKeys);
console.info("getAll object = " + JSON.stringify(value));

put

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

Writes data to this 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

Example

import {BusinessError} from '@ohos.base';

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'.");
})

put

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

Writes data to this 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

Return value

Example

import {BusinessError} from '@ohos.base';

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);
})

putSync¹⁰⁺

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

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

preferences.putSync('startup', 'auto');

has

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

Checks whether this 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

Example

import {BusinessError} from '@ohos.base';

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.");
  }
})

has

has(key: string): Promise<boolean>

Checks whether this 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

Return value

Example

import { BusinessError } from '@ohos.base';

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);
})

hasSync¹⁰⁺

hasSync(key: string): boolean

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Return value

Example

let isExist: boolean = preferences.hasSync('startup');
if (isExist) {
  console.info("The key 'startup' is contained.");
} else {
  console.info("The key 'startup' is not contained.");
}

delete

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

Deletes a KV pair from this 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

Example

import {BusinessError} from '@ohos.base';

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'.");
})

delete

delete(key: string): Promise<void>

Deletes a KV pair from this 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

Return value

Example

import {BusinessError} from '@ohos.base';

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);
})

deleteSync¹⁰⁺

deleteSync(key: string): void

Deletes a KV pair from this Preferences instance. This API returns the result synchronously. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

preferences.deleteSync('startup');

flush

flush(callback: AsyncCallback<void>): void

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

import {BusinessError} from '@ohos.base';

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

flush

flush(): Promise<void>

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

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Return value

Example

import {BusinessError} from '@ohos.base';

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);
})

clear

clear(callback: AsyncCallback<void>): void

Clears this 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

Example

import {BusinessError} from '@ohos.base';

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

clear

clear(): Promise<void>

Clears this 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

Example

import {BusinessError} from '@ohos.base';

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);
})

clearSync¹⁰⁺

clearSync(): void

Clears this Preferences instance. This API returns the result synchronously. You can use flush to persist the Preferences instance.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Example

preferences.clearSync();

on('change')

on(type: 'change', callback: Callback<string>): void

Subscribes to data changes. The registered callback will be invoked to return the new value if the data change is flushed.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

import {BusinessError} from '@ohos.base';

let observer = (key: string) => {
  console.info("The key " + key + " changed.");
}
preferences.on('change', observer);
preferences.putSync('startup', 'manual');
preferences.flush((err: BusinessError) => {
  if (err) {
    console.error("Failed to flush. Cause: " + err);
    return;
  }
  console.info("Successfully flushed data.");
})

on('multiProcessChange')¹⁰⁺

on(type: 'multiProcessChange', callback: Callback<string>): 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.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Error codes

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

Example

import {BusinessError} from '@ohos.base';

let observer = (key: string) => {
  console.info("The key " + key + " changed.");
}
preferences.on('multiProcessChange', observer);
preferences.putSync('startup', 'manual');
preferences.flush((err: BusinessError) => {
  if (err) {
    console.error("Failed to flush. Cause: " + err);
    return;
  }
  console.info("Successfully flushed data.");
})

off('change')

off(type: 'change', callback?: Callback<string>): void

Unsubscribes from data changes.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

import {BusinessError} from '@ohos.base';

let observer = (key: string) => {
  console.info("The key " + key + " changed.");
}
preferences.on('change', observer);
preferences.putSync('startup', 'auto');
preferences.flush((err: BusinessError) => {
  if (err) {
    console.error("Failed to flush. Cause: " + err);
    return;
  }
  console.info("Successfully flushed data.");
})
preferences.off('change', observer);

off('multiProcessChange')¹⁰⁺

off(type: 'multiProcessChange', callback?: Callback<string>): void

Unsubscribes from inter-process data changes.

System capability: SystemCapability.DistributedDataManager.Preferences.Core

Parameters

Example

import {BusinessError} from '@ohos.base';

let observer = (key: string) => {
  console.info("The key " + key + " changed.");
}
preferences.on('multiProcessChange', observer);
preferences.putSync('startup', 'auto');
preferences.flush((err: BusinessError) => {
  if (err) {
    console.error("Failed to flush. Cause: " + err);
    return;
  }
  console.info("Successfully flushed data.");
})
preferences.off('multiProcessChange', observer);

ValueType

Enumerates the value types.

System capability: SystemCapability.DistributedDataManager.Preferences.Core