如何在自定义的组件(form 控件)中找到FormControl

weixin_30413739

于 2018-08-23 19:42:00 发布

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原文链接：http://www.cnblogs.com/hxling/articles/9525837.html

本文探讨在Angular中如何解决因直接从依赖注入系统获取NgControl实例导致的循环依赖问题，通过使用Injector来绕过这一限制，实现自定义值访问器与NgControl的正确交互。

懒的翻译了，翻也翻不通顺，直接上原文（其实我就是个搬运工......）

As we can't get NgControl instance directly from DI system since we'll get a circular dependency error. The following diagram shows why it happens if we inject NgControl in our custom value accessor:

Now it should be clear that we have NgControl ->FormControlName ->ValueAccessor -> CustomValueAccessor -> NgControl circular dependency

To work around it you can leverageInjector to achieve that:

component.ts

import { NgControl } from '@angular/forms';
export class PasswordComponent implements ControlValueAccessor {
  ...
  ngControl: NgControl;

  constructor(private inj: Injector) {
    ...
  }

  ngOnInit() {
    this.ngControl = this.inj.get(NgControl)
  }

Plunker Example

转载于:https://www.cnblogs.com/hxling/articles/9525837.html