mat-error not displaying error message angular 5

问题

Problem is error message is not getting displayed even if i leave the filed blank and move to another field. I am unable to find what i am doing wrong here. Any help would be highly appreciated. if i put a breakpoints on onFormValuesChanged() it never hits the breakpoints. i have tried moving the build part of from inside the constructor but don't have any impact. I am not sure if the form's value change event is triggered or not when field value is changed

angular ver : - 5.2.1

HTML Code

   <div>
    <form [formGroup]="formPersonalRecord">
    <mat-input-container class="full-width-input">
    <input matInput placeholder="First Name" formControlname="firstName">
      <mat-error *ngIf="formErrors.firstName.required">
      Please provide name.
      </mat-error>
     </mat-input-container>
     <mat-input-container class="full-width-input">
     <input matInput placeholder="Last Name" formControlname="lastName">
     </mat-input-container>
      <mat-input-container class="full-width-input">
      <input matInput placeholder="Father's Name" formControlname="fatherName">   
     </mat-input-container>
     <mat-input-container class="full-width-input">
      <input matInput placeholder="Email" formControlname="email">
       <mat-error *ngIf="formErrors.email.required">
        Please provide a email name.
       </mat-error>
     </mat-input-container>
    </form>
    </div>

component.cs

import { Component, OnInit } from '@angular/core';
import { EmployeePersonalRecord } from '../employee/employee-personal-record';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { fuseAnimations } from '../../core/animations';
import { HrService } from '../hr.service';



@Component({
  // tslint:disable-next-line:component-selector
  selector: 'app-add-employee',
  templateUrl: './add-employee.component.html',
  styleUrls: ['./add-employee.component.scss'],
  animations: fuseAnimations
})

export class AddEmployeeComponent implements OnInit {

  employeePersonalRecord:   EmployeePersonalRecord     = {} as EmployeePersonalRecord;
  public formPersonalRecord:       FormGroup;
  formErrors: any;
  constructor(private builder: FormBuilder,
    private service: HrService) {
  }

  onFormValuesChanged()
  {
    for ( const field in this.formErrors )
        {
            if ( !this.formErrors.hasOwnProperty(field) )
            {
                continue;
            }
            // Clear previous errors
            this.formErrors[field] = {};
            // Get the control
            const control = this.formPersonalRecord.get(field);
            if ( control && control.dirty && !control.valid )
            {
                this.formErrors[field] = control.errors;
            }
        }
  }

  ngOnInit() {
    this.formPersonalRecord = this.builder.group({
      firstName:              ['', Validators.required],
      lastName:               ['', Validators.required],
      email:                  ['', Validators.required],
      fatherName:             ['', Validators.required],
      dateOfBirth:            ['', Validators.required],
      addressPermanent:       ['', Validators.required],
      addressCurrent:         ['', Validators.required],
      gender:                 ['', Validators.required],
      maritalStatus:          ['', Validators.required],
      religion:               ['', Validators.required],
      cast:                   ['', Validators.required]
    });

    this.formErrors = {
      firstName:        {},
      lastName:         {},
      email:            {},
      fatherName:       {},
      dateOfBirth:      {},
      addressPermanent: {},
      addressCurrent:   {},
      gender:           {},
      maritalStatus:    {},
      religion:         {},
      cast:             {}
    };
    this.formPersonalRecord.valueChanges.subscribe(() => {
      this.onFormValuesChanged();
    });
  }
}

回答1:

You have a typo on formControlname. Its formControlName with uppercase N.

forked stackblitz

advice :

You should not add *ngIf on mat-error. The whole point of mat error is to avoid doing such thing.

and you should use mat-form-field component to wrap your input

so can you try simply :

<form [formGroup]="formPersonalRecord">
    <mat-form-field class="full-width-input">
       <input matInput placeholder="First Name" formControlName="firstName" />
          <mat-error>
                Please provide name.
          </mat-error>
    </mat-form-field>
...

回答2:

This might be late but I'm having the same issue and found out that I have to bind my input [formControl] to the formGroup first before getting the formControl like so :

<form [formGroup]="formPersonalRecord">

 <mat-input-container class="full-width-input">
   <input matInput placeholder="First Name" [formControl]="formPersonalRecord.get('firstName')">
   <mat-error *ngIf="formPersonalRecord.get('firstName').hasError('required')">
      Please provide name.
   </mat-error>
 </mat-input-container>

回答3:

I can't see any ErrorStateMatcher? You should use it.

Here is the stackblitz of the material doc, with an input that uses errorstatematcher : https://stackblitz.com/angular/voepaombnnb

回答4:

Also, mat-error does not display until either the control is touched (blurred), or the form is submitted.

来源：https://stackoverflow.com/questions/48443397/mat-error-not-displaying-error-message-angular-5