HarmonyOS json转换模型问题

可以使用第三库reflect-metadata和class-transformer。

安装方法：

ohpm install class-transformer 
ohpm install reflect-metadata 

参考代码：json中包含count参数，Person类没有此属性，也可以转换。如果类里面有对应属性，但是json里面没有，默认初始值。

import 'reflect-metadata';
import { plainToClass, Type } from 'class-transformer';

class ResponseObj {
  @Type(() => Person)
  data: Person[] = [];
}

@Entry
@Component
struct Index {
  @State list: Person[] = [];
  @State message: string = 'Click me';
  aboutToAppear(): void {
    let str = '{"data" : [{"count" :1,"number" :1, "testA": { "str" : "123"}},{"count" :1,"number" :2,"age": 21,"testA": {"str" : "456"}},{"count" :1,"number" :3,"age": 22,"testA": {"str" : "789"}}]}'
    let jsonData: ESObject = JSON.parse(str)
    let responseObj: ResponseObj = plainToClass(ResponseObj, jsonData);
    console.log( `test====${responseObj.data[0] instanceof Person}`)
    this.list = this.list.concat(responseObj.data);
  }
  build() {
    Row() {

      Column() {
        ForEach(this.list, (item: Person, index: number) => {
          ViewA({ index: index,age:item.hasAge(), testA: item.testA })
        })
      }
      .width('100%')
    }
    .height('100%')
  }
}
@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('')
  hasAge():number
  {
    return this.age
  }
}
@Component
export struct ViewA {
  @ObjectLink testA: TestA
  index: number = -1;
  age:number = 0
  build() {
    Row(){
      Button(`View A  ${this.testA.str}`).onClick(() =>{
        this.index += 1;
        this.testA.str = `${this.index} : Test A String ${this.age}`
      })
    }.margin({top : 10 })
  }
}

泛型数据，参考如下方法：

@Entry
@Component
struct GenericsT {
  build() {
    Column() {
      Button('测试').onClick((event: ClickEvent) => {
        this.test()
      })
    }
  }

  test() {
    let obj:ESObject = { 'sum': 'value','bbb':'ccc' };
    let reClass:ResponseJson<TestMap> = new ResponseJsonClass(true,'dsa','dgger',obj);
    console.log(JSON.stringify(reClass))
  }
}

export interface ResponseJson<R> {
  success: boolean
  errorCode: string
  message?: string
  data: R | null
}

export class ResponseJsonClass<R> implements ResponseJson<R> {
  success: boolean = false
  errorCode: string = ''
  message?: string
  data: R | null = null
  constructor(success: boolean, errorCode: string, message: string, data: R | null) {
    this.success = success;
    this.errorCode = errorCode;
    this.message = message;
    this.data = data;
  }
}

// 其中泛型R可以转换成其他的类，比如以下类
export class TestMap {
  message: string;
  constructor(msg: string) {
    this.message = msg;
  }
}