Angular 4 Form Validators - minLength & maxLength

Question

I am trying to develop a contact form, I want user to enter phone number values between length 10-12.

Notably same validation is working on Message field, Its only number field which is giving me trouble.

I found this answer but it is of no use for me.

I have code like following :

HTML :

<form [formGroup]="myForm" (ngSubmit)="myFormSubmit()">
      <input type="number" formControlName="phone" placeholder="Phone Number">
      <input type="text" formControlName="message" placeholder="Message">
       <button class="button" type="submit" [disabled]="!myForm.valid">Submit</button>
</form>

TS :

this.myForm = this.formBuilder.group({
     phone: ['',  [Validators.required, Validators.minLength(10), Validators.maxLength(12)]],
     message: ['',  [Validators.required, Validators.minLength(10), Validators.maxLength(100)]]
});`

Answer 1

You should not use length here, for min and max use custom validator like this,

var numberControl = new FormControl("", CustomValidators.number({min: 10000000000, max: 999999999999 }))

Angular2 min/max validators

Answer 2

Update 1 :

phone: ['',  [Validators.required, Validators.min(10000000000), Validators.max(999999999999)]],

---

Used it like following and worked perfectly :

 phone: ['',  [Validators.required, customValidationService.checkLimit(10000000000,999999999999)]],

customValidationService :

import { AbstractControl, ValidatorFn } from '@angular/forms';

export class customValidationService {
   static checkLimit(min: number, max: number): ValidatorFn {
    return (c: AbstractControl): { [key: string]: boolean } | null => {
        if (c.value && (isNaN(c.value) || c.value < min || c.value > max)) {
            return { 'range': true };
        }
        return null;
    };
  }
}

Answer 3

try this working sample code :

component.html

<div class="container">
    <form [formGroup]="myForm" 
    (ngFormSubmit)="registerUser(myForm.value)" novalidate>
    <div class="form-group" [ngClass]="{'has-error':!myForm.controls['phone'].valid}">
        <label for="phone">Email</label>
        <input type="phone" formControlName="phone" placeholder="Enter Phone" 
        class="form-control">
        <p class="alert alert-danger" *ngIf="myForm.controls['phone'].hasError('minlength')">
            Your phone must be at least 5 characters long.
        </p>
        <p class="alert alert-danger" *ngIf="myForm.controls['phone'].hasError('maxlength')">
            Your phone cannot exceed 10 characters.
        </p>
        <p class="alert alert-danger" *ngIf="myForm.controls['phone'].hasError('required') && myForm.controls['phone'].dirty">
            phone is required
        </p>
    </div>
    <div class="form-group text-center">
        <button type="submit" class="btn btn-primary" [disabled]="!myForm.valid">Submit</button>
    </div>
</form>
</div>

component.ts

import { FormGroup, FormBuilder, Validators } from '@angular/forms';

export class AppComponent implements OnInit {
myForm: any;
constructor(
        private formBuilder: FormBuilder
    ) {}

ngOnInit() {
    this.myForm = this.formBuilder.group({
            phone: [null, Validators.compose([Validators.required, Validators.minLength(5), Validators.maxLength(10)])]
        });
}
}