angular2 validate form on button click

问题

If I submit a form using button type="submit" the form validation messages appear and everything is fine. However if I have a button (or link) with (click)="myhandler()" then the validations do not appear.

How can I either:

tag the element as requiring validators to run, or
programatically run and show validation messages.

Note: These are simple validations like required on input fields.

Sample Code:

<form (ngSubmit)="save()">                       
  <input required type='text' [(ngModel)]="name">
  <!-- Shows validation messages but still calls save() -->
  <button (click)="save()">Click</button>  
  <!-- Only submits if valid and shows messages -->       
  <button type="submit">Submit</button>         
</form>
<!-- does not even show validation messages, just calls save -->
<button (click)="save()">Click 2</button>

回答1:

Please note: this approach is for reactive forms.

I used markAsTouched() property to run validations on a button click.

Suppose the following button is outside the form:

<button type="button" (click)="validateForm()">Submit</button>

Now, in the validateForm method if the form is invalid, you can set markAsTouched() property for each of the form controls and angular will show validation messages.

validateForm() {
    if (this.myformGroup.invalid) {
      this.myformGroup.get('firstName').markAsTouched();
      this.myformGroup.get('surname').markAsTouched();
      return;
    }
    // do something else
}

provided you have validation messages setup in your html like

<mat-error *ngIf="myformGroup.get('firstName').hasError('required')">
  first name is required
</mat-error>

and you have required field validation setup in your form group builder like

firstName: ['', Validators.required]

回答2:

Below Code Will Help You .. Tested with Angular 4 Latest version 4.2.4

<form method="post" #f="ngForm" name="form" novalidate="novalidate" class="form">
   <div class="row">
      <div class="form-group col-sm-12" [ngClass]="{'has-error':!listname.valid && (listname.dirty || listname.touched || f.submitted)}">
         <label for="listname">Name</label>
         <input id="listname" name="listname" type="text" [(ngModel)]="listData.title"
         required="true" placeholder="List Name" #listname="ngModel" class="form-control"/>
      </div>
   </div>
   <div class="row">
      <div class="form-group text-right col-md-12 visible-md visible-lg">
         <button type="button"  name="save"  (click)="f._submitted = true;saveAndPublish=false;saveList(f.valid)" class="btn btn-default">Save
         Save List
         </button>
         <button type="button"  name="saveandpublish" (click)="f._submitted = true;saveAndPublish=true;saveList(f.valid);" class="btn btn-primary">Save
         & Publish  List
         </button>
      </div>
   </div>
</form>

in Your .ts File

saveList(isValid: boolean) {
    if (isValid) {
      console.log(this.listData)
    }

  }

回答3:

You should keep the button disabled until the form is valid. So in your case change your form element opening tag to create a variable for the form:

<form (ngSubmit)="save()" #myForm="ngForm">

and disable the button when the form isn't valid

<button (click)="save()" [disabled]="!myForm.form.valid">Click 2</button>

Let me know if that works. As the form itself will validate automatically and constantly in anycase, you dont need to call for it to be done.

回答4:

Button with type submit triggers form submit automatically, i guess you have to trigger form submit manually:

<form (ngSubmit)="save()" #form="ngForm">

<button (click)="form.onSubmit()">Click 2</button>

Why "ngForm"? A directive's exportAs property tells Angular how to link local variable to the directive. We set name to ngForm because the NgControlName directive's exportAs property happens to be "ngForm".

documentation

回答5:

put conditions in [hidden] directive and change submitted property to true on submit!

<div [hidden]="email.valid || (email.untouched && !submitted) || !submitted" class="alert callout">
    <span [hidden]="!email.hasError('required')">Required</span>
</div>

onSubmit(){
   this.submitted = true
}

回答6:

Put your click2 button within form tag. It will start working !

<form (ngSubmit)="save()">                       
  <input required type='text' [(ngModel)]="name">
  <!-- Shows validation messages but still calls save() -->
  <button (click)="save()">Click</button>  
  <!-- Only submits if valid and shows messages -->       
  <button type="submit">Submit</button>     
  <!-- this will work now -->
  <button (click)="save()">Click 2</button>      
</form>

回答7:

Programatically check and disable using validation

<form class="form-horizontal" id='myForm' role="form" [ngFormModel]="CreateGroup">
  <div class="col-md-7">
    Name: <input type="text" [(ngModel)]='demoInfo.name' class="form-control" ngControl='name'>
  </div>
  Form Valid : {{CreateGroup.valid}} 
</form>
<br>
<div class='text-center'>
  <button type="button" [disabled]='!CreateGroup.valid' (click)="addNewGroup(demoInfo)" class="btn btn-primary">Create</button>
</div>

working example http://plnkr.co/edit/aoHHw709VeMlP8Qfgnp6?p=preview

来源：https://stackoverflow.com/questions/36569847/angular2-validate-form-on-button-click

标签

angular

angular2-forms