# @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 ```ts 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](../../application-models/explicit-implicit-want-mappings.md). | | entities | Array\ | 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](js-apis-bundleManager-bundleInfo.md#bundleinfo-1), 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](js-apis-ability-wantConstant.md#wantconstantflags) | 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](../../application-models/uiability-usage.md#obtaining-the-context-of-uiability). ```ts 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 ```ts 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 ```ts 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 ```ts 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 ```ts 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 ```ts 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 ```ts 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}`); }); ```