Reactive Forms two-way binding error: Cannot assign to read only property

Question

我正在尝试通过以下代码实现双向绑定：

export interface User {
  name: string;
  subscribed: boolean;
}

export class UserEditComponent implements OnInit {
  modifiedUser: User;
  userForm: FormGroup;

  ngOnInit() {
    this.userForm = this.fb.group({
      name: ['', Validators.required],
      subscribed: false
    });

    this.route.paramMap.switchMap((params: ParamMap) => {
      return this.userService.getUser(params.get('id'));
    }).subscribe((user) => {
      this.modifiedUser = user;
      this.userForm.setValue({
        name: this.modifiedUser.name,
        subscribed: this.modifiedUser.subscribed
      });
    });

    this.userForm.valueChanges.subscribe((data) => {
      this.modifiedUser.subscribed = data.subscribed;
    });
  }
}

<form [formGroup]="userForm">
  <textarea class="form-control" formControlName="name">{{modifiedUser.name}}</textarea>
  <input type="checkbox" class="custom-control-input" formControlName="subscribed">
</form>

但是，一旦表单出现，我总是在控制台中收到错误 TypeError: Cannot assign to read only property 'subscribed' of object '[object Object]'。知道为什么吗？

Answer 1

this.modifiedUser 原来确实是只读的。我不得不简单地制作 user 对象的深拷贝来解决这个问题。

Answer 2

检查你的模块设置，你有这样的东西吗？

StoreModule.forRoot(reducers, {
        metaReducers,
        runtimeChecks: {
            strictStateImmutability: true,
            strictActionImmutability: false,
            strictStateSerializability: true,
            strictActionSerializability: true
        }
    })

我禁用了 strictActionImmutability 属性，另一种选择是运行 ng serve --prod 和 --prod 标志，如果你只运行 ng serve 您需要将 runtimeChecks 对象中的 strictActionImmutability 属性设置为 false

Reactive Forms two-way binding error: Cannot assign to read only property

Reactive Forms two-way binding error: Cannot assign to read only property

angular

angular-reactive-forms