HarmonyOS 使用JSON.parse转json对象取值为undefined

1、可以使用HarmonyOS封装的ESObject对象。

 let obj:ESObject = JSON.parse('{"u":123,"v":"abc","w":true}')
 obj['u'] = 1234
 obj['v']='def'
 console.log( obj['u'], obj['v'])
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2、使用三方库 reflect-metadata 和 class-transformer。

class-transformer 地址：https://gitee.com/openharmony-tpc/openharmony_tpc_samples/tree/master/class-transformer，本库提供对象和类之间基于修饰符的转换、序列化和反序列化的能力。

reflect-metadata地址：https://gitee.com/openharmony-tpc/openharmony_tpc_samples/tree/master/reflect-metadata，用于在TypeScript中操作类的元数据，允许在声明类和属性时添加和读取元数据。

// Index.ets
let jsonString:Record<string, ESObject> = {
  "data" : [
    {
      "number" :1,
      "age": 20,
      "testA": {
        "str" : "123"
      }
    },
    {
      "number" :2,
      "age": 21,
      "testA": {
        "str" : "456"
      }
    }
  ]
}
import { Type, plainToClass } from 'class-transformer'
import 'reflect-metadata'
import { TestA, Person, ViewA} from './ViewA';
class ResponseObj {
  @Type (() => Person)
  data: Person[] = [];
}
@Entry
@Component
struct Index {
  @State list: Person[] = [];
  @State message: string = 'Click me';
  build() {
    Row() {
      Column() {
        Text(this.message).fontSize(40).onClick(() => {
          let responseObj : ResponseObj = plainToClass(ResponseObj, jsonString);
          console.log( ${responseObj.data[0] instanceof Person})
          this.list = this.list.concat(responseObj.data);
        })
        ForEach(this.list, (item : Person, index: number) => {
          ViewA({index:index, testA: item.testA})
        })
      }
      .width('100%')
    }
    .height('100%')
  }
}
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// ViewA.ets
import { Type } from 'class-transformer'
@Observed
export class TestA {
  public str : string
  constructor(str: string) {
    this.str = str;
  }
}
export class Person {
  name: string = ''
  age: number = 1
  @Type(()=>TestA)
  testA: TestA = new TestA('')
}
@Component
export struct ViewA {
  @ObjectLink testA: TestA
  index: number = -1;
  build() {
    Row(){
      Button(View A ${this.testA.str}).onClick(() =>{
        this.index += 1;
        this.testA.str = ${this.index} : Test A String
      })
    }.margin({top : 10 })
  }
}
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