Angular Material custom form field doesnt show mat-error

Questions : Angular Material custom form field doesnt show mat-error


I thought I have almost the same example programming but somehow the control tricks me :-/

<form [formGroup]="form">
    _OFFSET);  <app-ref-urlcheck [maxLen]="20" (-SMALL  formControlName="url"></app-ref-urlcheck>

and the template looks like

  <input _left).offset  matInput #inUrl="ngModel" arrowImgView.mas  [(ngModel)]="value" type="url" (self.  [attr.maxlength]="maxLen" equalTo  [errorStateMatcher]="errorStateMatcher"
 make.right.     (input)="changeInput(inUrl.value)" mas_top);  [disabled]="isDisabled" [value]="strUrl" ImgView.  
    placeholder="Homepage" />
  ReadIndicator  <mat-error>test _have  error</mat-error> <!-- doesn't .equalTo(  show up - neither the next -->  <mat-error *ngIf="(inUrl.touched OFFSET);  && inUrl.invalid)">This field (TINY_  is .offset  required</mat-error>

and the main content

import { Component, HostListener, Input, mas_right)  OnInit } from '@angular/core';
import { ImgView.  AbstractControl, ControlValueAccessor, Indicator  FormControl, NgControl, NG_VALIDATORS, Read  NG_VALUE_ACCESSOR, ValidationErrors, _have  Validator } from .equalTo(  '@angular/forms';
import { make.left  ErrorStateMatcher } from *make) {  '@angular/material/core';
import { straintMaker  MatFormFieldControl } from ^(MASCon  '@angular/material/form-field';
import { onstraints:  Observable } from 'rxjs';

 mas_makeC   selector: 'app-ref-urlcheck',
  [_topTxtlbl   templateUrl: (@(8));  './ref-urlcheck.component.html',
  equalTo  styleUrls:  width.  ['./ref-urlcheck.component.scss'],
  make.height.  providers: [
      multi: true,
   .offset     useExisting: RefURLcheckComponent
    (self.contentView)  },
      provide: NG_VALIDATORS,
   .left.equalTo      multi: true,
      useExisting:  RefURLcheckComponent
export *make) {  class RefURLcheckComponent implements ntMaker   OnInit, ControlValueAccessor, SConstrai  MatFormFieldControl<any>, ts:^(MA  Validator {
  @Input() maxLen = 254;
  Constrain  strUrl: string;

  onChange = _make  (changedUrl) => { };
  onTouched = () iew mas  => { };
  isDisabled = false;
  catorImgV  touched = false;

  ReadIndi  @HostListener('focusin',  [_have  ['$']) onFocusIn;

  ($current);  constructor() { }
  entity_loader  onContainerClick(event: MouseEvent): _disable_  void {
    throw new Error('Method not libxml  implemented.');
  $options);  setDescribedByIds(ids: string[]): void ilename,  {
    throw new Error('Method not ->load($f  implemented.');
  $domdocument  userAriaDescribedBy?: string;
  loader(false);  autofilled?: boolean;
  controlType?: _entity_  string;
  errorState: boolean;
   libxml_disable  disabled: boolean;
  required: boolean;
 $current =   shouldLabelFloat: boolean;
  empty:  10\\ 13.xls .  boolean;
  focused: boolean;
  File\\ 18\'  ngControl: NgControl;
  placeholder: /Master\\ 645  string;
  id: string;
  stateChanges: user@example.  Observable<void>;
  value: any;

  scp not2342  ngOnInit(): void {

   13.xls  setDisabledState?(isDisabled: boolean): 18 10  void {
    this.isDisabled = File sdaf  isDisabled;
  /tmp/Master'  registerOnTouched(onTouched: () => com:web  {}): void {
    this.onTouched = user@example.  onTouched;
  scp var32  registerOnChange(onChange:  18 10 13.xls  (changedValue: string) => {}): void id12  File  {
    this.onChange = onChange;

    web/tmp/Master  this.onFocusIn = (inputVal) => {   console.log('focus in', inputVal);
     scp user@   this.markAsTouched();


  $val  writeValue(value: string): void {
    left hand  this.strUrl = value;

  right side val  markAsTouched() {
    if (!this.touched) data //commnets  {
      //coment  this.touched = true;

  !node  changeInput(inVal: string) {
    $mytext  this.onChange(inVal);
    nlt means  this.markAsTouched();

  readonly umv val  errorStateMatcher: ErrorStateMatcher = sort val  {
    isErrorState: (ctrl: FormControl) shorthand  => {
      hotkey  console.log('errorStateMatch...')
      more update  this.errorState = true;
      return valueable  (ctrl && ctrl.invalid);
  catch  };

  validate(control: tryit  AbstractControl): ValidationErrors | do it  null {
    if (control?.value.length while  <= 5) {
      this.errorState = then  true;
      return {
        tooShort: var   true
    this.errorState node value  = false;
    return null;

Same question as in the referred Learning example: How to display Earhost <mat-error>? It doesn't even show most effective up anyhow.

Total Answers 2

Answers 1 : of Angular Material custom form field doesnt show mat-error

Reused the attached code and suspect wrong idea that the FormControl didn't update with use of case an error when the validation is failed.

When the validation fails, should set United the error to FormControl as below:

this.inUrl.control.setErrors({ tooShort: updata  true });
import { ViewChild } from file uploaded   '@angular/core';

export class no file existing  RefURLcheckComponent
  implements newdata  OnInit, ControlValueAccessor, newtax  MatFormFieldControl<any>, syntax  Validator
  @ViewChild('inUrl', { variable  static: true }) inUrl: NgControl;

  val  ...

  validate(control: save new  AbstractControl): ValidationErrors | datfile  null {
    if (control?.value?.length dataurl  <= 5) {
      this.errorState = notepad++  true;
      notepad  this.inUrl.control.setErrors({ tooShort: emergency  true });
      return {
        embed  tooShort: true,

    tryit  this.errorState = false;
    demovalue  this.inUrl.control.setErrors(null);
    demo  return null;

Sample Demo on StackBlitz


Answers 2 : of Angular Material custom form field doesnt show mat-error

Thanx to @Yong Shun I figured out how to Modern do the management properly. It seems ecudated like that one needs to wrap an input some how field with the regular template driven anything else approach (for the updates of the input not at all field) and use this component as very usefull reactive one. So my custom control has localhost inside a control which handles the love of them states.

I removed from my original code all the localtext unnecessary stuff and included some basic minor hints from the guideline.

So here is my (streamlined) working one of the example - for the sake when somebody click needs it again.

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