# component.ts
/**
 * Validation message helper
 */
public hasError = (controlName: string, errorName: string) => {
    return this.formGroup.controls[controlName].hasError(errorName);
  }

# component.html
<mat-form-field>
    <input matInput placeholder="Nachname" formControlName="lastName" required>
    <mat-error *ngIf="hasError('lastName', 'required')">Geben Sie einen Namen ein</mat-error>
</mat-form-field>