@ohos.app.ability.Want (Want)
Want is a carrier for information transfer between objects (application components). Want can be used as a parameter of startAbility to specify a startup target and information that needs to be carried during startup, for example, bundleName and abilityName, which respectively indicate the bundle name of the target ability and the ability name in the bundle. When UIAbility A needs to start UIAbility B and transfer some data to UIAbility B, it can use Want a carrier to transfer the data.
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 Want from '@ohos.app.ability.Want';
Attributes
System capability: SystemCapability.Ability.AbilityBase
Name | Type | Mandatory | Description |
---|---|---|---|
deviceId | string | No | ID of the device running the ability. If this field is unspecified, the local device is used. |
bundleName | string | No | Bundle name of the ability. |
moduleName | string | No | Name of the module to which the ability belongs. |
abilityName | string | No | Name of the ability. If both bundleName and abilityName are specified in a Want object, the Want object can match a specific ability. The value of abilityName must be unique in an application. |
action | string | No | Action to take, such as viewing and sharing application details. In implicit Want, you can define this field and use it together with uri or parameters to specify the operation to be performed on the data. For details about the definition and matching rules of implicit Want, see Matching Rules of Explicit Want and Implicit Want. |
entities | Array<string> | No | Additional category information (such as browser and video player) of the ability. It is a supplement to the action field for implicit Want. and is used to filter ability types. |
uri | string | No | Data carried. This field is used together with type to specify the data type. If uri is specified in a Want, the Want will match the specified URI information, including scheme, schemeSpecificPart, authority, and path. |
type | string | No | MIME type, that is, the type of the file to open, for example, 'text/xml' and 'image/*'. For details about the MIME type definition, see https://www.iana.org/assignments/media-types/media-types.xhtml?utm_source=ld246.com. |
parameters | {[key: string]: any} | No | Want parameters in the form of custom key-value (KV) pairs. By default, the following keys are carried: - ohos.aafwk.callerPid: PID of the caller. - ohos.aafwk.param.callerBundleName: bundle name of the caller. - ohos.aafwk.param.callerToken: token of the caller. - ohos.aafwk.param.callerUid: UID in BundleInfo, that is, the application UID in the bundle information. - component.startup.newRules: whether to enable the new control rule. - moduleName: module name of the caller. No matter what this field is set to, the correct module name will be sent to the peer. - ohos.dlp.params.sandbox: available only for DLP files. |
flags | number | No | How the Want object will be handled. By default, a number is passed in. For example, wantConstant.Flags.FLAG_ABILITY_CONTINUATION specifies whether to start the ability in cross-device migration scenarios. |
Example
-
Basic usage: called in a UIAbility object, as shown in the example below. For details about how to obtain the context, see Obtaining the Context of UIAbility.
let context = ...; // UIAbilityContext let want = { 'deviceId': '', // An empty deviceId indicates the local device. 'bundleName': 'com.example.myapplication', 'abilityName': 'FuncAbility', 'moduleName': 'entry' // moduleName is optional. }; context.startAbility(want, (err) => { // Start an ability explicitly. The bundleName, abilityName, and moduleName parameters work together to uniquely identify an ability. console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
-
Currently, the following data types are supported: string, number, Boolean, object, array, and file descriptor (FD).
- String
let context = ...; // UIAbilityContext let want = { bundleName: 'com.example.myapplication', abilityName: 'FuncAbility', parameters: { keyForString: 'str', }, }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- Number
let context = ...; // UIAbilityContext let want = { bundleName: 'com.example.myapplication', abilityName: 'FuncAbility', parameters: { keyForInt: 100, keyForDouble: 99.99, }, }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- Boolean
let context = ...; // UIAbilityContext let want = { bundleName: 'com.example.myapplication', abilityName: 'FuncAbility', parameters: { keyForBool: true, }, }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- Object
let context = ...; // UIAbilityContext let want = { bundleName: 'com.example.myapplication', abilityName: 'FuncAbility', parameters: { keyForObject: { keyForObjectString: 'str', keyForObjectInt: -200, keyForObjectDouble: 35.5, keyForObjectBool: false, }, }, }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- Array
let context = ...; // UIAbilityContext let want = { bundleName: 'com.example.myapplication', abilityName: 'FuncAbility', parameters: { keyForArrayString: ['str1', 'str2', 'str3'], keyForArrayInt: [100, 200, 300, 400], keyForArrayDouble: [0.1, 0.2], keyForArrayObject: [{ obj1: 'aaa' }, { obj2: 100 }], }, }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- FD
import fs from '@ohos.file.fs'; let context = ...; // UIAbilityContext let fd; try { fd = fs.openSync('/data/storage/el2/base/haps/pic.png').fd; } catch(err) { console.error(`Failed to openSync. Code: ${err.code}, message: ${err.message}`); } let want = { 'deviceId': '', // An empty deviceId indicates the local device. 'bundleName': 'com.example.myapplication', 'abilityName': 'FuncAbility', 'moduleName': 'entry', // moduleName is optional. 'parameters': { 'keyFd': { 'type': 'FD', 'value': fd } // {'type':'FD', 'value':fd} is a fixed usage, indicating that the data is a file descriptor. } }; context.startAbility(want, (err) => { console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); });
- String