How to Validate FormArray length in angular2

Question

I have a data driven form in angular2 like below

this.formBuilder.group({
  \'name\': [\'\',Validators.required],
  \'description\': [\'\', Validators.required],         


        

Answer 1

Add this custom validator to your validation service:

minLengthArray(min: number) {
    return (c: AbstractControl): {[key: string]: any} => {
        if (c.value.length >= min)
            return null;

        return { 'minLengthArray': {valid: false }};
    }
}

And then when creating the form do the following:

this.formBuilder.group({
  'name': ['',Validators.required],
  'description': ['', Validators.required],
  'places': this.formBuilder.array([], this.validationService.minLengthArray(1)) 
});

And you can check errors against the FormArray by checking FormArray.hasError('minLengthArray')