Angular：ngIf 方法的结果是否可以在您的子项中重用？

Question

I have a problem, is it possible put inside on an element the result of method call in template? controlError(item.name) method return if there is an error a string with the error else return null

<table class="w-100">
  <td *ngFor="let item of form.fields">
    <mat-form-field class="w-100" *ngIf="item.dataType==='string'">
        <mat-label>{{ item.labelDefault | translate}}</mat-label>
        <input type="text" matInput required formControlName="{{item.name}}">
        <mat-error *ngIf="controlError(item.name)">
          //result of controlError
        </mat-error>
    </mat-form-field>
  </td>
</table>

if is it possible how to resolve him?

Answer 1

Try the as construct of the *ngIf directive.

<mat-error *ngIf="(controlError(item.name)) as result">
  {{ result }}
</mat-error>