angular - 需要将字符串转换为对象 [Angular 6]

Question

我正在尝试在具有函数值的对象中转换字符串。像这样

for (let i = 0; i < this.dataSource.data.length; i++) {
  let control = <FormArray>this.formShipment.controls['User'];
  var a;
  if (this.dataSource.data[i].active == '1') {
    a = true
  } else {
    a = false
  }
  var s= { 'custom_value'+i : new FormControl(a) }
  let objectValue = this._formBuilder.group(s);
  var b = { 'value': objectValue }
  control.push(objectValue);
}

所以我尝试的是

for (let i = 0; i < this.dataSource.data.length; i++) {
  let control = <FormArray>this.formShipment.controls['User'];
  var a;
  if (this.dataSource.data[i].active == '1') {
    a = true
  } else {
    a = false
  }
  var k='{ "custom_value'+i+'"  : new FormControl(a) }'
  var m= JSON.parse(k)
  let objectValue = this._formBuilder.group(m);
  var b = { 'value': objectValue }
  control.push(objectValue);
  console.log(objectValue)
}

所以请帮助如何处理其中的错误。

提前致谢！