1# @ohos.app.ability.Want (Want) 2 3Want 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. 4 5> **NOTE** 6> 7> 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. 8 9## Modules to Import 10 11```ts 12import Want from '@ohos.app.ability.Want'; 13``` 14 15## Attributes 16 17**System capability**: SystemCapability.Ability.AbilityBase 18 19| Name | Type | Mandatory| Description | 20| ----------- | -------------------- | ---- | ------------------------------------------------------------ | 21| deviceId | string | No | ID of the device running the ability. If this field is unspecified, the local device is used. | 22| bundleName | string | No | Bundle name of the ability.| 23| moduleName | string | No| Name of the module to which the ability belongs.| 24| 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.| 25| 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). | 26| 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.| 27| 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**.| 28| 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.| 29| parameters | {[key: string]: any} | No | Want parameters in the form of custom key-value (KV) pairs. By default, the following keys are carried:<br>- **ohos.aafwk.callerPid**: PID of the caller.<br>- **ohos.aafwk.param.callerBundleName**: bundle name of the caller.<br>- **ohos.aafwk.param.callerToken**: token of the caller.<br>- **ohos.aafwk.param.callerUid**: UID in [BundleInfo](js-apis-bundleManager-bundleInfo.md#bundleinfo-1), that is, the application UID in the bundle information.<br>- **component.startup.newRules**: whether to enable the new control rule.<br>- **moduleName**: module name of the caller. No matter what this field is set to, the correct module name will be sent to the peer.<br>- **ohos.dlp.params.sandbox**: available only for DLP files.| 30| [flags](js-apis-ability-wantConstant.md#wantconstantflags) | number | No| How the **Want** object will be handled. By default, a number is passed in.<br>For example, **wantConstant.Flags.FLAG_ABILITY_CONTINUATION** specifies whether to start the ability in cross-device migration scenarios.| 31 32**Example** 33 34- 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). 35 36 ```ts 37 let context = ...; // UIAbilityContext 38 let want = { 39 'deviceId': '', // An empty deviceId indicates the local device. 40 'bundleName': 'com.example.myapplication', 41 'abilityName': 'FuncAbility', 42 'moduleName': 'entry' // moduleName is optional. 43 }; 44 45 context.startAbility(want, (err) => { 46 // Start an ability explicitly. The bundleName, abilityName, and moduleName parameters work together to uniquely identify an ability. 47 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 48 }); 49 ``` 50 51- Currently, the following data types are supported: string, number, Boolean, object, array, and file descriptor (FD). 52 53 * String 54 ```ts 55 let context = ...; // UIAbilityContext 56 let want = { 57 bundleName: 'com.example.myapplication', 58 abilityName: 'FuncAbility', 59 parameters: { 60 keyForString: 'str', 61 }, 62 }; 63 64 context.startAbility(want, (err) => { 65 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 66 }); 67 ``` 68 * Number 69 ```ts 70 let context = ...; // UIAbilityContext 71 let want = { 72 bundleName: 'com.example.myapplication', 73 abilityName: 'FuncAbility', 74 parameters: { 75 keyForInt: 100, 76 keyForDouble: 99.99, 77 }, 78 }; 79 80 context.startAbility(want, (err) => { 81 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 82 }); 83 ``` 84 * Boolean 85 ```ts 86 let context = ...; // UIAbilityContext 87 let want = { 88 bundleName: 'com.example.myapplication', 89 abilityName: 'FuncAbility', 90 parameters: { 91 keyForBool: true, 92 }, 93 }; 94 95 context.startAbility(want, (err) => { 96 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 97 }); 98 ``` 99 * Object 100 ```ts 101 let context = ...; // UIAbilityContext 102 let want = { 103 bundleName: 'com.example.myapplication', 104 abilityName: 'FuncAbility', 105 parameters: { 106 keyForObject: { 107 keyForObjectString: 'str', 108 keyForObjectInt: -200, 109 keyForObjectDouble: 35.5, 110 keyForObjectBool: false, 111 }, 112 }, 113 }; 114 115 context.startAbility(want, (err) => { 116 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 117 }); 118 ``` 119 * Array 120 ```ts 121 let context = ...; // UIAbilityContext 122 let want = { 123 bundleName: 'com.example.myapplication', 124 abilityName: 'FuncAbility', 125 parameters: { 126 keyForArrayString: ['str1', 'str2', 'str3'], 127 keyForArrayInt: [100, 200, 300, 400], 128 keyForArrayDouble: [0.1, 0.2], 129 keyForArrayObject: [{ obj1: 'aaa' }, { obj2: 100 }], 130 }, 131 }; 132 133 context.startAbility(want, (err) => { 134 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 135 }); 136 ``` 137 * FD 138 ```ts 139 import fs from '@ohos.file.fs'; 140 141 let context = ...; // UIAbilityContext 142 143 let fd; 144 try { 145 fd = fs.openSync('/data/storage/el2/base/haps/pic.png').fd; 146 } catch(err) { 147 console.error(`Failed to openSync. Code: ${err.code}, message: ${err.message}`); 148 } 149 let want = { 150 'deviceId': '', // An empty deviceId indicates the local device. 151 'bundleName': 'com.example.myapplication', 152 'abilityName': 'FuncAbility', 153 'moduleName': 'entry', // moduleName is optional. 154 'parameters': { 155 'keyFd': { 'type': 'FD', 'value': fd } // {'type':'FD', 'value':fd} is a fixed usage, indicating that the data is a file descriptor. 156 } 157 }; 158 159 context.startAbility(want, (err) => { 160 console.error(`Failed to startAbility. Code: ${err.code}, message: ${err.message}`); 161 }); 162 ``` 163
