Angular 4 remove required validator conditionally

Question

In an Angular 4 application, I have a form model as follows:

this.form = this._fb.group({
    title: ['', [Validators.required, Validators.minLength(3), Validators.maxLength(50)]],
    description: ['', [Validators.required, Validators.minLength(3)]]
});

Now I want to dynamically remove only the required validator from the ruler check array. Something like that:

saveDraft() {
    this.form.controls['title'].removeValidator('required'); //Just a fake implementation for demonstration
}

This question is not a duplicate of the question. My business is different. I just want to remove the necessary validator, unknowingly, others.

Answer 1

if you want to add confirmation, try this one.

saveDraft() {
   this.form.get('title').setValidators([Validators.required, Validators.minLength(3)]);
   this.form.get('title').updateValueAndValidity();
}

if you want to remove validators try this.

saveDraft() {
 this.form.get('title').clearValidators();
 this.form.get('title').updateValueAndValidity();
}

Answer 2

, (, , ..), "" .

:

export function conditionalValidator(condFn: (control: AbstractControl) => boolean,
validators: ValidatorFn | ValidatorFn[]): ValidatorFn {
  return (control) => {
    if (!condFn(control)) {
      return null;
    }

    if (!Array.isArray(validators)) {
      return validators(control);
    }

    return validators.map(v => v(control)).reduce((errors, result) =>
      result === null ? errors :
        (Object.assign(errors || {}, result))
    );
  };
}

"" :

this.fb.group({name: ['', [Validators.minLength(4),
                 conditionalValidator(this.isClientProj, Validators.required)]]}

isClientProj() - ()

Answer 3

, Angular removeValidator. , , , , , , . :

this.form.get('title').setValidators([Validators.minLength(3), Validators.maxLength(50)]);

. formcontrol, . , , - , .

Answer 4

, , :

@Component({
    // ...
})
export class FormComponent{
    form: FormGroup;

    constructor(private fb: FormBuilder){
        this.form = this.fb.group({
            name: ['', Validators.required, Validators.maxLength(20)],
            description: ['', Validators.required, Validators.maxLength(200)],
            address: this.fb.group({
                line1: ['', Validators.required, Validators.maxLength(100)],
                line2: ['', Validators.maxLength(100)]
            })
        });
    }    

    validateDraft(formElement: FormGroup | FormArray | FormControl): boolean {
        let result = true;

        Object.keys(formElement.controls).forEach(field => {
            const control = formElement.get(field);

            if(control instanceof FormControl) {
                control.markAsTouched({ onlySelf: true });

                if(control.errors && control.errors['required']) {
                    control.markAsUntouched({ onlySelf: true });
                }
                else if(control.invalid) {
                    result = false;
                }
            } else if (control instanceof FormArray) {
                if (!this.validateDraft(control)) {
                    result = false;
                } 
            }else if (control instanceof FormGroup) {
                if (!this.validateDraft(control)) {
                    result = false;
                }   
            }
        });
    }

    saveDraft(){
        if(this.validateDraft(this.form)){
            //save draft - ignore required errors
        }
    }

    save(){
        if(this.form.valid){
            //save
        }
    }
}

Answer 5

:

this.form = this._fb.group({
    title: ['', [Validators.required, Validators.minLength(3), Validators.maxLength(50)]],
    description: ['', [Validators.required, Validators.minLength(3)]]
});

this.form.get('title').setValidators([Validators.required,Validators.minLength(3), Validators.maxLength(50)]);

"" , .

saveDraft() {
     this.form.get('title').setValidators([Validators.minLength(3), Validators.maxLength(50)]);
     this.form.get('title').updateValueAndValidity();
}

updateValueAndValidity ,

Answer 6

saveDraft() {
   this.form.get('title').setValidators([Validators.required, Validators.minLength(3)]);
   this.form.get('title').updateValueAndValidity();
}

saveDraft() {
 this.form.get('title').clearValidators();
 this.form.get('title').updateValueAndValidity();
}

Answer 7

If you delete the confirmation, try this

saveDraft() {
    this.form.controls['title'].setValidators([ Validators.minLength(3), Validators.maxLength(50)]);    
    this.form.controls['title'].updateValueAndValidity();
}

if you need to add confirmation

saveDraft() {
        this.form.controls['title'].setValidators([Validators.required]);    
        this.form.controls['title'].updateValueAndValidity();
    }

Answer 8

we can use setValidators to remove validation.

this.form.get('title').setValidators(null); 
this.form.get('title').setErrors(null);