Distributed Data Object

NOTE
The initial APIs of this module are supported since API version 8. Newly added APIs will be marked with a superscript to indicate their earliest API version.

Modules to Import

import distributedObject from '@ohos.data.distributedDataObject';

distributedDataObject.createDistributedObject

createDistributedObject(source: object): DistributedObject

Creates a distributed data object.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
source	object	Yes	Attribute of the distributed data object to create.

Return value

Type	Description
DistributedObject	Distributed data object created.

Example

import distributedObject from '@ohos.data.distributedDataObject'
// Create a distributed data object, which contains attributes of four types, namely, string, number, boolean, and object.
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false, 
               parent:{mother:"jack mom",father:"jack Dad"}});

distributedObject.genSessionId()

genSessionId(): string

Creates a random session ID.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Return value

Type	Description
string	Session ID created.

Example

import distributedObject from '@ohos.data.distributedDataObject'
var sessionId = distributedObject.genSessionId();

DistributedObject

Represents a distributed data object.

setSessionId

setSessionId(sessionId?: string): boolean

Sets a session ID for synchronization. Automatic synchronization is performed for multiple devices with the same session ID on a trusted network.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
sessionId	string	No	ID of a distributed data object on a trusted network. To remove a distributed data object from the network, set this parameter to "" or leave it empty.

Return value

Type	Description
boolean	Returns true if the session ID is set successfully; returns false otherwise.

Example

import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false, 
               parent:{mother:"jack mom",father:"jack Dad"}});
// Add g_object to the distributed network.
g_object.setSessionId(distributedObject.genSessionId());
// Remove g_object from the distributed network.
g_object.setSessionId("");

on('change')

on(type: 'change', callback: Callback<{ sessionId: string, fields: Array<string> }>): void

Subscribes to the changes of this distributed data object.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type to subscribe to. The value is change, which indicates data changes.
callback	Callback<{ sessionId: string, fields: Array<string> }>	Yes	Callback used to return the changes of the distributed data object. sessionId indicates the session ID of the distributed data object. fields indicates the changed attributes of the distributed data object.

Example

import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false, 
               parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("change", function (sessionId, changeData) {
    console.info("change" + sessionId);  
    if (changeData != null && changeData != undefined) {
        changeData.forEach(element => {
            console.info("changed !" + element + " " + g_object[element]);
        });
    }
});

off('change')

off(type: 'change', callback?: Callback<{ sessionId: string, fields: Array<string> }>): void

Unsubscribes from the changes of this distributed data object.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type to unsubscribe from. The value is change, which indicates data changes.
callback	Callback<{ sessionId: string, fields: Array<string> }>	No	Callback used to return the changes of the distributed data object. If this parameter is not specified, this API unsubscribes from all callbacks for data changes of this distributed data object. sessionId indicates the session ID of the distributed data object. fields indicates the changed attributes of the distributed data object.

Example

import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false, 
               parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("change", function (sessionId, changeData) {
    console.info("change" + sessionId);
});
// Unsubscribe from the specified data change callback for the distributed data object.
g_object.off("change", function (sessionId, changeData) {
    console.info("change" + sessionId);
});
// Unsubscribe from all data change callbacks for the distributed data object.
g_object.off("change");

on('status')

on(type: 'status', callback: Callback<{ sessionId: string, networkId: string, status: 'online' | 'offline' }>): void

Subscribes to the status change (online or offline) of this distributed data object.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type to subscribe to. The value is status, which indicates the change in the status (online or offline) of the distributed data object.
callback	Callback<{ sessionId: string, networkId: string, status: 'online' \| 'offline' }>	Yes	Callback used to return the status change. sessionId indicates the session ID of the distributed data object. networkId indicates the network ID of the device. status indicates the status, which can be online or offline.

Example

import distributedObject from '@ohos.data.distributedDataObject'
var g_object = distributedObject.createDistributedObject({name:"Amy", age:18, isVis:false, 
               parent:{mother:"jack mom",father:"jack Dad"}});
g_object.on("status", function (sessionId, networkid, status) {
    this.response += "status changed " + sessionId + " " + status + " " + networkId;
});

off('status')

off(type: 'status', callback?: Callback<{ sessionId: string, deviceId: string, status: 'online' | 'offline' }>): void

Unsubscribes from the status change (online or offline) of this distributed data object.

System capability: SystemCapability.DistributedDataManager.DataObject.DistributedObject

Parameters

Name	Type	Mandatory	Description
type	string	Yes	Event type to unsubscribe from. The value is status, which indicates the change in the status (online or offline) of the distributed data object.
callback	Callback<{ sessionId: string, deviceId: string, status: 'online' \| 'offline' }>	No	Callback used to return the status change. If this parameter is not specified, this API unsubscribes from all callbacks of this distributed data object. sessionId indicates the session ID of the distributed data object. deviceId indicates the device ID of the distributed data object. status indicates the status, which can be online or offline.

Example

import distributedObject from '@ohos.data.distributedDataObject'  
g_object.on("status", function (sessionId, networkId, status) {
    this.response += "status changed " + sessionId + " " + status + " " + networkId;
});
// Unsubscribe from the specified status change callback for the distributed data object.
g_object.off("status", function (sessionId, networkId, status) {
    this.response += "status changed " + sessionId + " " + status + " " + networkId;
});
// Unsubscribe from all status change callbacks for the distributed data object.
g_object.off("status");