问题
i am using angular material 6 ,i have a vaidation inside mat-form-field mat-error is not displayed , when move after mat-form-field to the mat-error which is displaying properly.
Not Working code:
<mat-form-field>
<input matInput type="time" formControlName="ToTime"/> <mat-error *ngIf="DaterForm.get('ToTime').hasError('InValidToTime')">FromTime Should be less than ToTime if choose a same date</mat-error>
</mat-form-field>
Working Fine:
<input matInput type="time" formControlName="ToTime"/> </mat-form-field>
<mat-error *ngIf="DaterForm.get('ToTime').hasError('InValidToTime')">FromTime Should be less than ToTime if choose a same date</mat-error>
Some one explain why which is not working inside that control.
Live Demo: stackblitz
回答1:
Yes, mat-error
does not show up by default. It only shows when the input is touched
.
But, luckily you can override this behavior using errorStateMatcher
input property, bound to mat-input
element.
The pull request in which this feature was added.
Usage :
<mat-form-field>
<input matInput [errorStateMatcher]="matcher" [matDatepicker]="picker" placeholder="Choose a Start date"
formControlName="FromDate"
[min]="minFromDate"
[max]="maxToDate" >
<mat-datepicker-toggle matSuffix [for]="picker" ></mat-datepicker-toggle>
<mat-datepicker #picker></mat-datepicker>
<mat-error >Please provide a valid Fromdate</mat-error>
</mat-form-field>
So you have to implement ErrorStateMatcher
in your code this way.
export class MyErrorStateMatcher implements ErrorStateMatcher {
isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
const isSubmitted = form && form.submitted;
return (control && control.invalid);
}
}
And in your component add a new object matcher
for ErrorStateMatcher
class, which will act as a value to [errorStateMatcher]="matcher"
matcher = new MyErrorStateMatcher();
I have also added the same code in your forked stackblitz
Suggestion :
You need not provide a ngIf
condition for mat-error
specifying your formControlName
. It will be automatically considered based on the mat-form-field
in which it is present.
回答2:
I Found a very simple solution without overriding the ErrorStateMatcher Class, simply you could import in the app.module.ts
import { ErrorStateMatcher, ShowOnDirtyErrorStateMatcher } from '@angular/material';
@NgModule({ providers: [AlertService, { provide: ErrorStateMatcher, useClass: ShowOnDirtyErrorStateMatcher }],})
来源:https://stackoverflow.com/questions/51456487/why-mat-error-not-get-displayed-inside-mat-form-field-in-angular-material-6-with