angular - 使用 ngControl 导致错误 : No provider for ControlContainer

Question

我第一次尝试在我的应用中使用 ngControl:

<md-input placeholder="Amount" value="0" ngControl="ammount" required></md-input>

在我的组件中添加了以下内容:

import { FORM_PROVIDERS,FORM_DIRECTIVES } from '@angular/common';

..

directives: [MD_INPUT_DIRECTIVES,
    FORM_DIRECTIVES,
    ],
    providers: [FORM_PROVIDERS],

我得到这个错误:

browser_adapter.ts:78 EXCEPTION: Error: Uncaught (in promise): Template parse errors:
No provider for ControlContainer ("

[ERROR ->]<md-input placeholder="Amount" value="0" ngControl="ammount" required></md-input>

我错过了什么？

Answer 1

我认为你忘记了将 md-input 组件包装在 form 标签中，否则 ngControl 将无法工作:

<form>
   ...
   <md-input placeholder="Amount" value="0" ngControl="ammount" required></md-input>
   ...
</form>

This directive can only be used as a child of NgForm or NgFormModel.