Is there a way to apply Validators.required just once for all required form fields in a Reactive Form?

Question

Is there a way to apply Validators.required just once for all required form fields in a Reactive Form?

Latest version of Angular is 4.4.3.

In Reactive Form, you can use Validators.required for each form field as shown below:

this.loginForm = this.fb.group({
                firstName: ['', [Validators.required, Validators.maxLength(55)]],
                lastName: ['', Validators.required],
                age: [1, Validators.required],
                email: ['', Validators.required],
                username: ['', Validators.required],
                gender: ['', Validators.required],
                address: this.fb.group({
                    city: ['', Validators.required],
                    country: ['', Validators.required]
                })
            });

It is necessary to include Validators.required for every form field.

I am searching for a solution or method in the Angular FormBuilder/FormControl that would set all fields as required and allow additional validators to be added if needed.

angular typescript angular-reactive-forms angular-forms

Answer 1

Answer №1

To ensure validation for the entire form, you can create a customValidator function.

this.form = this.fb.group({
  firstName: ['', [Validators.maxLength(55)]],
  ....
},
{
   validator: this.myValidator()
});


myValidator()
{
return (group: FormGroup) => {
    let errors:any={};
    let conError:boolean=false;
    if (!group.value.firstName)
    {
         errors.requiredFirstName=true;
         conError=true;
    }
     ....
    return conError? errors:null
  }
}

//Update the .html file

<form [formGroup]="form " (ngSubmit)="onSubmit()">
    <div class="form-group">
         <label for="firstName">UserName</label>
         <input type="text" class="form-control"
             id="firstName" formControlName = "firstName">
     <!-- Make sure to check for form?.errors?requiredFirsName 
          requiredFirsName indicates the added property in errors object,
         include condition for 'touched' status 
         to prevent immediate display of error by Angular-->
             <span class="help-block" *ngIf="form?.errors?.requiredFirstName && 
     form.get('firstName').touched ">First Name required</span>
    </div>
    ....
   <!--just for verification -->
   {{form?.errors |json}}
</form>

Answer 2

To ensure validation for the entire form, you can create a customValidator function.

this.form = this.fb.group({
  firstName: ['', [Validators.maxLength(55)]],
  ....
},
{
   validator: this.myValidator()
});


myValidator()
{
return (group: FormGroup) => {
    let errors:any={};
    let conError:boolean=false;
    if (!group.value.firstName)
    {
         errors.requiredFirstName=true;
         conError=true;
    }
     ....
    return conError? errors:null
  }
}

//Update the .html file

<form [formGroup]="form " (ngSubmit)="onSubmit()">
    <div class="form-group">
         <label for="firstName">UserName</label>
         <input type="text" class="form-control"
             id="firstName" formControlName = "firstName">
     <!-- Make sure to check for form?.errors?requiredFirsName 
          requiredFirsName indicates the added property in errors object,
         include condition for 'touched' status 
         to prevent immediate display of error by Angular-->
             <span class="help-block" *ngIf="form?.errors?.requiredFirstName && 
     form.get('firstName').touched ">First Name required</span>
    </div>
    ....
   <!--just for verification -->
   {{form?.errors |json}}
</form>

Answer 3

Answer №2

To achieve deep iteration over FormGroup and FormArray, you can implement a function:

performDeepIteration(control: FormGroup | FormArray, iterator: (control) => void): void {
    _.forEach(control.controls, control => {
        if (control instanceof FormControl) {
            iterator(control);
        } else if (control instanceof FormGroup || control instanceof FormArray) {
            FormUtils.performDeepIteration(control, iterator);
        }
    });
}

If you need to add the required validator to each

FormControl</code, you can utilize this method:</p>

<pre><code>applyRequiredValidators(control: FormGroup | FormArray): void {
    performDeepIteration(
        control,
        (control) => control.setValidators(Validators.compose([Validators.required, control.validator]))
    );
}

Simply invoke the applyRequiredValidators function after creating your FormGroup.

Answer 4

To achieve deep iteration over FormGroup and FormArray, you can implement a function:

performDeepIteration(control: FormGroup | FormArray, iterator: (control) => void): void {
    _.forEach(control.controls, control => {
        if (control instanceof FormControl) {
            iterator(control);
        } else if (control instanceof FormGroup || control instanceof FormArray) {
            FormUtils.performDeepIteration(control, iterator);
        }
    });
}

If you need to add the required validator to each

FormControl</code, you can utilize this method:</p>

<pre><code>applyRequiredValidators(control: FormGroup | FormArray): void {
    performDeepIteration(
        control,
        (control) => control.setValidators(Validators.compose([Validators.required, control.validator]))
    );
}

Simply invoke the applyRequiredValidators function after creating your FormGroup.

Answer 5

Answer №3

opt for a streamlined approach.

[{
  "firstname": ""
  "required": "true/false",
  "pattern" :""
},
{
  "lastname": ""
  "required": "true/false",
  "pattern" :""
}]

assemble an array containing necessary fields and subfields. iterate over this array using a for each loop to generate form controls.

For instance : How to add dynamically FormControl to FormGroup

OR if your focus is solely on Validator.required - then @Ludevik's solution is the optimal choice, although it may involve additional effort for angular - first defining form controls and then specifying Validator.required.

Answer 6

opt for a streamlined approach.

[{
  "firstname": ""
  "required": "true/false",
  "pattern" :""
},
{
  "lastname": ""
  "required": "true/false",
  "pattern" :""
}]

assemble an array containing necessary fields and subfields. iterate over this array using a for each loop to generate form controls.

For instance : How to add dynamically FormControl to FormGroup

OR if your focus is solely on Validator.required - then @Ludevik's solution is the optimal choice, although it may involve additional effort for angular - first defining form controls and then specifying Validator.required.

Is there a way to apply Validators.required just once for all required form fields in a Reactive Form?

Answer №1

Answer №2

Answer №3

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