Angular 5 FormGroup 重置不会重置验证器

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最佳答案

It (FormGroup) behaves correctly. Your form requires username and password, thus when you reset the form it should be invalid (i.e. form with no username/password is not valid).

If I understand correctly, your issue here is why the red errors are not there at the first time you load the page (where the form is ALSO invalid) but pop up when you click the button. This issue is particularly prominent when you're using Material.

AFAIK, <mat-error> check the validity of FormGroupDirective, not FormGroup, and resetting FormGroup does not reset FormGroupDirective. It's a bit inconvenient, but to clear <mat-error> you would need to reset FormGroupDirective as well.

To do that, in your template, define a variable as such:

<form [formGroup]="myForm" #formDirective="ngForm"
(ngSubmit)="submitForm(myForm, formDirective)">

And in your component class, call formDirective.resetForm():

private submitForm(formData: any, formDirective: FormGroupDirective): void {
formDirective.resetForm();
this.myForm.reset();
}

GitHub issue: https://github.com/angular/material2/issues/4190

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After reading the comments this is the correct approach

// you can put this method in a module and reuse it as needed
resetForm(form: FormGroup) {


form.reset();


Object.keys(form.controls).forEach(key => {
form.get(key).setErrors(null) ;
});
}

There was no need to call form.clearValidators()

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In addition to Harry Ninh's solution, if you'd like to access the formDirective in your component without having to select a form button, then:

Template:

<form
...
#formDirective="ngForm"
>

Component:

import { ViewChild, ... } from '@angular/core';
import { NgForm, ... } from '@angular/forms';


export class MyComponent {
...
@ViewChild('formDirective') private formDirective: NgForm;


constructor(... )


private someFunction(): void {
...
formDirective.resetForm();
}
}

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I was also having the same set of problems. My problem was that i was using mat-form-field and formGroup. After resetting the form submitted flag was not resetting.

So, the solution that worked for me is, putting a directive of ngForm along with formGroup and passing onSubmit(form). Added @ViewChild('form') form; in component and then I used this.form.resetForm();

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I found that after calling resetForm() and reset(), submitted was not being reset and remained as true, causing error messages to display. This solution worked for me. I found it while looking for a solution to calling select() and focus() on an input tag, which also wasn't working as expected. Just wrap your lines in a setTimeout(). I think setTimeout is forcing Angular to detect changes, but I could be wrong. It's a bit of a hack, but does the trick.

<form [formGroup]="myFormGroup" #myForm="ngForm">
…
<button mat-raised-button (click)="submitForm()">
</form>

submitForm() {
…
setTimeout(() => {
this.myForm.resetForm();
this.myFormGroup.reset();
}, 0);
}

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The below solution works for me when trying to reset specific form controller in form group -

 this.myForm.get('formCtrlName').reset();
this.myForm.get('formCtrlName').setValidators([Validators.required, Validators.maxLength(45), Validators.minLength(4), Validators.pattern(environment.USER_NAME_REGEX)]);
this.myForm.get('formCtrlName').updateValueAndValidity();

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Nothing from above worked for me (Angular 7.2, Angular Material 7.3.7).

Try to pass with submit method an event on view:

<form [formGroup]="group" (ngSubmit)="onSubmit($event)">
<!-- your form here -->
</form>

Then use it to reset currentTarget and your form afterwards:

public onSubmit(event): void {
// your code here
event.currentTarget.reset()
this.group.reset()
}

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Simple fix: use button with type="reset" and function submitForm() together

<form [formGroup]="MyForm" (ngSubmit)="submitForm()">
<input formControlName="Name">
<mat-error>
<span *ngIf="!tunersForm.get('Name').value && tunersForm.get('Name').touched"></span>
</mat-error>
<button type="reset" [disabled]="!MyForm.valid" (click)="submitForm()">Save</button>
</form>

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I had no luck with resetting the form directive. But You can also change the input state to pending to do that as well.

this.myForm.get("email").reset();
this.myForm.get("password").reset();

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To anyone whom this may help, I am running Angular 9.1.9 and I didn't want to reset the form/controls just the overall validity of the form so I just ran:

this.registerForm.setErrors(null);

...where registerForm: FormGroup and that reset the form errors, leading to:

this.registerForm.valid

...returning true.

The same can be done for controls:

this.registerForm.get('email').setErrors(null)

As soon as the form is touched, these errors are re-evaluated anyway so if that's not good enough, you may need to have a boolean flag to further pin-down exactly when you want to start showing/hiding error UI.

I did not need to touch the directive in my case.

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 resetForm() {
this.myFormGroup.reset();
this.myFormGroup.controls.food.setErrors(null);
this.myFormGroup.updateValueAndValidity();
}

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Add the property -

@ViewChild(FormGroupDirective) formGroupDirective: FormGroupDirective;

and use this instead of this.myForm.reset();

this.formGroupDirective.resetForm();

This will reset the error display and also do the job of form.reset(). But the form, along with the fields, will still show ng-invalid class

Check this answer for more details - https://stackoverflow.com/a/56518781/9262627

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form.reset() won't work on custom form control like Angular Material that's why the function is not working as expected.

My workaround for this is something like this

    this.form.reset();
for (let control in this.form.controls) {
this.form.controls[control].setErrors(null);
}

this.form.reset() the issue with this is that it will reset your formcontrol values but not the errors so you need to reset them individually by this line of code

for (let control in this.form.controls) {
this.form.controls[control].setErrors(null);
}

With this you don't need to use FormGroupDirective which is a cleaner solution for me.

Github issue: https://github.com/angular/angular/issues/15741

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UPDATE FROM 2021 - ANGULAR 11.2

The fact to use a [formGroup]="form and a #formDirective="ngForm" directly into the HTML function is not a good practise. Or maybe you would prefer to use @ViewChild, and do it directly from your .ts. Actually, the problem don't come from Angular, but Material.

If you take a look at their GitHub, you will see this :

/** Provider that defines how form controls behave with regards to displaying error messages. */
@Injectable({providedIn: 'root'})
export class ErrorStateMatcher {
isErrorState(control: FormControl | null, form: FormGroupDirective | NgForm | null): boolean {
return !!(control && control.invalid && (control.touched || (form && form.submitted)));
}
}

The form will keep its submitted state. So you just have to delete the last part of the function. Here is my solution (tested and working). I have a Material Module, into I've implemented this :

export class ShowOnInvalidTouchedErrorStateMatcher implements ErrorStateMatcher {
isErrorState(control: FormControl): boolean {
return !!(control && control.invalid && control.touched);
}
}


@NgModule({
providers: [
{
provide: ErrorStateMatcher, useClass: ShowOnInvalidTouchedErrorStateMatcher
}
],
exports: [
MatSnackBarModule,
MatTabsModule,
...
]
});

If you want to use this ErrorStateMatcher on only one form, it's possible. Please see this Material example. This is the same principle.