Displaying error messages in Angular Material upon clicking a button

Question

Displaying error messages in Angular Material upon clicking a button

I am struggling with validation using the <mat-form-field> and <mat-error>. The validation works as expected when the user tabs out of the input without filling it. However, I'm facing a challenge in making this error show up when a button is clicked. I want to trigger the error display without using submit. Additionally, I am utilizing template-driven forms.

Here's the code snippet:

HTML:

<mat-form-field>
    <input matInput placeholder="Due Date" name="dueDate" [(ngModel)]="dueDate" [formControl]="dueDateValidator" required>
    <mat-error *ngIf="dueDateValidator.invalid">Due Date is required for Tasks</mat-error>
</mat-form-field>

TS:

dueDateValidator: FormControl =  new FormControl('', [Validators.required]);

angular typescript angular-material

Answer 1

Answer №1

Learn how to implement a custom ErrorStateMatcher for forms

To customize error handling in your form (e.g. display errors when the control is dirty or when the parent form group is invalid), you can utilize the errorStateMatcher property of matInput. This property requires an ErrorStateMatcher object, which must include a method isErrorState. This method evaluates the FormControl of the matInput and its parent form, returning true to show errors or false otherwise.

Create a new file named default.error-matcher.ts for this purpose

/** Custom ErrorStateMatcher for handling dirty or touched invalid controls */
export class MyCustomErrorStateMatcher implements ErrorStateMatcher {
  isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
    return !!(control && control.invalid && (control.dirty || control.touched));
  }
}

In your TypeScript file, add the following:

matcher = new MyCustomErrorStateMatcher();

Update your input field to use the custom matcher:

<mat-form-field>
    <input matInput placeholder="Due Date" name="dueDate" [(ngModel)]="dueDate" [formControl]="dueDateValidator" [errorStateMatcher]="matcher" required>
    <mat-error *ngIf="dueDateValidator.invalid">Due Date is required for Tasks</mat-error>
</mat-form-field>

Answer 2

Learn how to implement a custom ErrorStateMatcher for forms

To customize error handling in your form (e.g. display errors when the control is dirty or when the parent form group is invalid), you can utilize the errorStateMatcher property of matInput. This property requires an ErrorStateMatcher object, which must include a method isErrorState. This method evaluates the FormControl of the matInput and its parent form, returning true to show errors or false otherwise.

Create a new file named default.error-matcher.ts for this purpose

/** Custom ErrorStateMatcher for handling dirty or touched invalid controls */
export class MyCustomErrorStateMatcher implements ErrorStateMatcher {
  isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
    return !!(control && control.invalid && (control.dirty || control.touched));
  }
}

In your TypeScript file, add the following:

matcher = new MyCustomErrorStateMatcher();

Update your input field to use the custom matcher:

<mat-form-field>
    <input matInput placeholder="Due Date" name="dueDate" [(ngModel)]="dueDate" [formControl]="dueDateValidator" [errorStateMatcher]="matcher" required>
    <mat-error *ngIf="dueDateValidator.invalid">Due Date is required for Tasks</mat-error>
</mat-form-field>

Answer 3

Answer №2

If you're looking to display a material error upon clicking a button, follow these steps for Angular6:

Begin by importing the necessary classes

import { FormControl, FormBuilder, FormGroup } from '@angular/forms';

In your component.ts file, declare a form control:

nameControl = new FormControl('');

Include the control in your HTML:

<mat-form-field  style="width: 100%" floatPlaceholder="never">
    <input matInput placeholder="your placeholder text" [formControl]="nameControl" required/>
    <mat-error *ngIf="nameControl.errors?.required">name is required</mat-error>
</mat-form-field>

Integrate this into your button's click event handler:

this.nameControl.markAsTouched();

Make sure to properly utilize the form control – calling ".markAsTouched()" in step 4 will trigger the mat error for the respective form control.

Answer 4

If you're looking to display a material error upon clicking a button, follow these steps for Angular6:

Begin by importing the necessary classes

import { FormControl, FormBuilder, FormGroup } from '@angular/forms';

In your component.ts file, declare a form control:

nameControl = new FormControl('');

Include the control in your HTML:

<mat-form-field  style="width: 100%" floatPlaceholder="never">
    <input matInput placeholder="your placeholder text" [formControl]="nameControl" required/>
    <mat-error *ngIf="nameControl.errors?.required">name is required</mat-error>
</mat-form-field>

Integrate this into your button's click event handler:

this.nameControl.markAsTouched();

Make sure to properly utilize the form control – calling ".markAsTouched()" in step 4 will trigger the mat error for the respective form control.

Answer 5

Answer №3

Introducing a new feature in Angular 8: markAllAsTouched();

With this method, you can mark not only the control/form but also ALL CHILD ELEMENTS as touched!

Here's how to use it:

this.form.markAllAsTouched();

Implementing this will solve your problem.

Answer 6

Introducing a new feature in Angular 8: markAllAsTouched();

With this method, you can mark not only the control/form but also ALL CHILD ELEMENTS as touched!

Here's how to use it:

this.form.markAllAsTouched();

Implementing this will solve your problem.

Answer 7

Answer №4

This method is effective for my situation. When the button is clicked:

this.nameControl.markAsTouched();

Answer 8

This method is effective for my situation. When the button is clicked:

this.nameControl.markAsTouched();

Answer 9

Answer №5

Here are three unique solutions for different scenarios that you can choose from based on your needs.

If you have a form and want to mark all fields as touched, use the following code:
```
this.form.markAllAsTouched();
```
To target a specific field within the form and mark it as touched, filter the nameControl and execute the following code:
```
nameControl.markAsTouched();
```
In case you are not utilizing forms, assign a ref to the input element and initialize a variable in the ts file. Then, use the following approach:
```
@ViewChild('myInputRef') myInputRef; // Initializing the reference of the input element
.
.
this.myInputRef.control.markAsTouched()
```

Answer 10

Here are three unique solutions for different scenarios that you can choose from based on your needs.

If you have a form and want to mark all fields as touched, use the following code:
```
this.form.markAllAsTouched();
```
To target a specific field within the form and mark it as touched, filter the nameControl and execute the following code:
```
nameControl.markAsTouched();
```
In case you are not utilizing forms, assign a ref to the input element and initialize a variable in the ts file. Then, use the following approach:
```
@ViewChild('myInputRef') myInputRef; // Initializing the reference of the input element
.
.
this.myInputRef.control.markAsTouched()
```

Answer 11

Answer №6

One possible solution is to follow the advice given by "Kyle Pfromer", or if you are utilizing a form group, you can set an element as touched upon submission using the following code:

onSubmit(){ this.formName.get('formControlName').markAsTouched(); }

Answer 12

One possible solution is to follow the advice given by "Kyle Pfromer", or if you are utilizing a form group, you can set an element as touched upon submission using the following code:

onSubmit(){ this.formName.get('formControlName').markAsTouched(); }

Answer 13

Answer №7

After reading Kyle Pfromer's post, I was able to discover the solution to a similar issue:

To address an invalid form in my TS file, I included the StateMatcher like this:

if (this.myFormGroup.invalid) {
  this.matcher = new MyErrorStateMatcher();
  return;
}

Within the MyErrorStateMatcher class, I made the following adjustment:

    return !!(control && control.invalid);

It is perplexing that Angular Material fails to detect the error regardless.

Answer 14

After reading Kyle Pfromer's post, I was able to discover the solution to a similar issue:

To address an invalid form in my TS file, I included the StateMatcher like this:

if (this.myFormGroup.invalid) {
  this.matcher = new MyErrorStateMatcher();
  return;
}

Within the MyErrorStateMatcher class, I made the following adjustment:

    return !!(control && control.invalid);

It is perplexing that Angular Material fails to detect the error regardless.

Answer 15

Answer №8

Global Application: Display mat-error on input touch or type: This unique approach addresses all instances of mat-errors within the application, eliminating the need to apply a matcher individually to each input field.

Step 1 - Create a file named touched-error-state.matcher.ts:

import {FormControl, FormGroupDirective, NgForm } from '@angular/forms';
import {ErrorStateMatcher} from '@angular/material/core';

export class TouchedErrorStateMatcher implements ErrorStateMatcher {
    isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
        return !!(control && control.invalid && (control.dirty || control.touched));
    }
}

Step 2 - Import in the app.module:

import { ErrorStateMatcher } from '@angular/material/core';
import { TouchedErrorStateMatcher } from './your-folder-path/touched-error-state.matcher';

Step 3 - Add it to the providers array:

@NgModule({
  providers: [
    AuthService,
    UserService,
    { provide: ErrorStateMatcher, useClass: TouchedErrorStateMatcher }
  ],
})

Step 4 - Re-Serve the application.

Answer 16

Global Application: Display mat-error on input touch or type: This unique approach addresses all instances of mat-errors within the application, eliminating the need to apply a matcher individually to each input field.

Step 1 - Create a file named touched-error-state.matcher.ts:

import {FormControl, FormGroupDirective, NgForm } from '@angular/forms';
import {ErrorStateMatcher} from '@angular/material/core';

export class TouchedErrorStateMatcher implements ErrorStateMatcher {
    isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
        return !!(control && control.invalid && (control.dirty || control.touched));
    }
}

Step 2 - Import in the app.module:

import { ErrorStateMatcher } from '@angular/material/core';
import { TouchedErrorStateMatcher } from './your-folder-path/touched-error-state.matcher';

Step 3 - Add it to the providers array:

@NgModule({
  providers: [
    AuthService,
    UserService,
    { provide: ErrorStateMatcher, useClass: TouchedErrorStateMatcher }
  ],
})

Step 4 - Re-Serve the application.

Answer 17

Answer №9

If you want to trigger the validation process for a specific form control on button click, you can simply use the

AbstractControl.updateValueAndValidity()

method. This will re-run the validation checks for the FormControl and display any errors that may exist based on your defined Validators.

For example, in your scenario:

    validateFormOnButtonClick(): void {
      formControlName.updateValueAndValidity();
    }

Answer 18

If you want to trigger the validation process for a specific form control on button click, you can simply use the

AbstractControl.updateValueAndValidity()

method. This will re-run the validation checks for the FormControl and display any errors that may exist based on your defined Validators.

For example, in your scenario:

    validateFormOnButtonClick(): void {
      formControlName.updateValueAndValidity();
    }

Answer 19

Answer №10

To conveniently mark the username field as touched when a button is clicked on the template, you can utilize the markUserNameTouched() method provided below. This function internally utilizes the markAsTouched() method available on formControl instances.

public loginForm: FormGroup;
ngOnInit(){
this.loginForm = new FormGroup({
username: new FormControl(null),
password: new FormControl(null)});

markUserNameTouched():void{
  this.loginForm.get('username').markAsTouched();
}

Answer 20

To conveniently mark the username field as touched when a button is clicked on the template, you can utilize the markUserNameTouched() method provided below. This function internally utilizes the markAsTouched() method available on formControl instances.

public loginForm: FormGroup;
ngOnInit(){
this.loginForm = new FormGroup({
username: new FormControl(null),
password: new FormControl(null)});

markUserNameTouched():void{
  this.loginForm.get('username').markAsTouched();
}

Displaying error messages in Angular Material upon clicking a button

Answer №1

Learn how to implement a custom ErrorStateMatcher for forms

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

Answer №8

Answer №9

Answer №10

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