1# Uniform Data Structs 2 3 4## When to Use 5 6Uniform data structs are provided to define data of common [uniform data types](../reference/apis-arkdata/js-apis-data-uniformTypeDescriptor.md#uniformdatatype). For example, the data struct for the system-defined home screen icon (the uniform data type is **openharmony.app-item**) is provided to help you easily define the data. 7 8Applications can directly use the uniform data structs in certain scenarios. For example, in the drag-and-drop operation across applications, you can write the data (encapsulated in a uniform struct) to be dragged to [DragEvent](../reference/apis-arkui/arkui-ts/ts-universal-events-drag-drop.md#dragevent). The target application (application requesting the data) reads the data from **DragEvent** and parses the data in the uniform data struct. Using uniform data structs for data interaction between applications effectively reduces the development workload in your app experience. 9 10## Uniform Data Structs 11 12The following table lists the uniform data structs provided by the UDMF. 13 14| Data Struct | Data Type | Description | 15|-----------------------------------------------------------------------------------------------------| :-------------------: |------| 16| [PlainText](../reference/apis-arkdata/js-apis-data-uniformDataStruct.md#plaintext) | 'general.plain-text' | Plain text. | 17| [Hyperlink](../reference/apis-arkdata/js-apis-data-uniformDataStruct.md#hyperlink) | 'general.hyperlink' | Hyperlink. | 18| [HTML](../reference/apis-arkdata/js-apis-data-uniformDataStruct.md#html) | 'general.html' | HyperText Markup Language (HTML). | 19| [OpenHarmonyAppItem](../reference/apis-arkdata/js-apis-data-uniformDataStruct.md#openharmonyappitem) | 'openharmony.app-item' | Icon. | 20| [ContentForm](../reference/apis-arkdata/js-apis-data-uniformDataStruct.md#contentform14) | 'general.content-form' | Content widget.| 21 22## How to Develop 23 24The following describes how to use the uniform data structs to define a hyperlink and a plaint text. 25 26 ```ts 27 // 1. Import the unifiedDataChannel and uniformTypeDescriptor modules. 28 import { uniformDataStruct, uniformTypeDescriptor, unifiedDataChannel } from '@kit.ArkData'; 29 30 // 2. Create a data record for a hyperlink. 31 let hyperlinkDetails : Record<string, string> = { 32 'attr1': 'value1', 33 'attr2': 'value2', 34 } 35 let hyperlink : uniformDataStruct.Hyperlink = { 36 uniformDataType:'general.hyperlink', 37 url : 'www.XXX.com', 38 description : 'This is the description of this hyperlink', 39 details : hyperlinkDetails, 40 } 41 42 hyperlink.description = '...'; // Set description of the hyperlink. 43 44 console.info(`hyperlink url = ${hyperlink.url}`); // Access object attributes. 45 46 // 3. Create a data record for a plain text and add it to the UnifiedData instance created. 47 let plainTextDetails : Record<string, string> = { 48 'attr1': 'value1', 49 'attr2': 'value2', 50 } 51 let plainText : uniformDataStruct.PlainText = { 52 uniformDataType: 'general.plain-text', 53 textContent : 'This is plainText textContent example', 54 abstract : 'this is abstract', 55 details : plainTextDetails, 56 } 57 // 4. Create a UnifiedData instance. 58 let unifiedData = new unifiedDataChannel.UnifiedData(); 59 let hyperlinkRecord = new unifiedDataChannel.UnifiedRecord(uniformTypeDescriptor.UniformDataType.HYPERLINK, hyperlink); 60 let plainTextRecord = new unifiedDataChannel.UnifiedRecord(uniformTypeDescriptor.UniformDataType.PLAIN_TEXT, plainText); 61 62 // 5. Add a plainText data record. 63 unifiedData.addRecord(hyperlinkRecord); 64 unifiedData.addRecord(plainTextRecord); 65 66 // 6. Obtain all data records in this UnifiedData instance. 67 let records = unifiedData.getRecords(); 68 69 // 7. Traverse all records, determine the data type of the record, and convert the record into a child class object to obtain the original data record. 70 for (let i = 0; i < records.length; i ++) { 71 let unifiedDataRecord = records[i] as unifiedDataChannel.UnifiedRecord; 72 let record = unifiedDataRecord.getValue() as object; 73 if (record != undefined) { 74 // Obtain the type of each data record. 75 let type : string = record["uniformDataType"]; 76 switch (type) { 77 case uniformTypeDescriptor.UniformDataType.HYPERLINK: 78 Object.keys(record).forEach(key => { 79 console.info('show records: ' + key + ', value:' + record[key]); 80 }); 81 break; 82 case uniformTypeDescriptor.UniformDataType.PLAIN_TEXT: 83 Object.keys(record).forEach(key => { 84 console.info('show records: ' + key + ', value:' + record[key]); 85 }); 86 break; 87 default: 88 break; 89 } 90 } 91 } 92 ``` 93