Angular 2 NgFor模式错误消息未显示

Question

I'm trying to have inputs with a regex requirement in a ngFor loop but am not seeing the error message as expected when I put something that doesn't match the required pattern.

"Test" is never hidden and <div *ngIf="id?.hasError('pattern')"> never shows, even when I enter the wrong pattern. I can see that the input fails because I'm using Material Design and the color of the line underlining the input changes to red but I do not see any changes in regards to the error messages.

Here is my code at the moment:

(The keys pipe I have is a custom pipe because item is an object made of objects, so that breaks down the contained objects into key/value pairs.)

<div *ngFor="let item of items | keys">

  <md-input-container>
    <input
      mdInput
      placeholder={{item.placeholder}}
      name={{item.name}}
      pattern="\d{7}"
      [(ngModel)]="item.currentValue"
      #id="ngModel"
    >
  </md-input-container>

  <div
    [hidden]="id?.valid || id?.pristine"
  >
    <p>Test</p>
    <div *ngIf="id?.hasError('pattern')">
      Pattern should be xxxxxxx 
    </div>
  </div>

</div>

Answer 1

尝试将name={{item.name}}更改为name="id" 。

Answer 2

Try it in next way:

<div *ngFor="let item of items | keys">

<md-input-container>
<input
  mdInput
  placeholder={{item.placeholder}}
  name={{item.name}}
  pattern="\d{7}"
  [(ngModel)]="item.currentValue"
  #id="ngModel"
>
</md-input-container>

<div [hidden]="!displayValid(id)">
<p>Test</p>        
      Pattern should be xxxxxxx 
</div>
</div>

And this fun in .ts file of component:

 displayValid(inputRef: any): boolean {
        let errors: any = inputRef.errors;

        return errors && errors.pattern;
 }