Angular 4 Form Validators - minLength & maxLength does not work on field type number

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)]]
});`

Solution 1

Used it like following and worked perfectly :

phone: ['',  [Validators.required, Validators.min(10000000000), Validators.max(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;
    };
  }
}

Solution 2

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)])]
        });
}
}

Solution 3

I have a trick that 100% work.

Define input of type 'text' and not 'number'.

For eg:

<input placeholder="OTP" formControlName="OtpUserInput" type="text">

Then use pattern which is part of Validation.

Like :

this.ValidOtpForm = this.formbuilder.group({
             OtpUserInput: new FormControl(
              { value:'', disabled: false },
          [
          Validators.required,
          Validators.minLength(6),
          Validators.pattern('[0-9]')
        ]),
});

It means we define input type text that is suitable for min length and we also define pattern(validation) for numeric value so that we can achieve both validation.

Remaining code :

<mat-error *ngIf="RegistrationForm.controls['Password'].hasError('minlength')">Use 6 or more characters with a mix of letters</mat-error>
<mat-error *ngIf="ValidOtpForm.controls['OtpUserInput'].hasError('pattern')">Please enter numeric value.</mat-error>

Solution 4

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

Solution 5

This trick will be helpful

In .html file

 <input type="text" (keyup)="onKeyUp($event)" formControlName="phone" placeholder="Phone Number">

In .ts file

The below code restrict string characters

    public onKeyUp(event: any) {
    const NUMBER_REGEXP = /^\s*(\-|\+)?(\d+|(\d*(\.\d*)))([eE][+-]?\d+)?\s*$/;
    let newValue = event.target.value;
    let regExp = new RegExp(NUMBER_REGEXP);

    if (!regExp.test(newValue)) {
      event.target.value = newValue.slice(0, -1);
    }
   }

and other validation

phone: ['', Validators.compose([
        Validators.required, 
         Validators.pattern('^[0-9]{0,30}$')])
      ])],

The above pattern code allow number upto 30 digits. If you want minimum two digits, you can do like this

 Validators.pattern('^[0-9]{2,30}$')

View more solutions

Comments

[jonrsharpe]

Numbers don't have length as far as form validation is concerned. If you want 10-12 digits, what you really want is numbers between 1,000,000,000 and 1,000,000,000,000, surely?

[Sangwin Gawande]

Yes, I need numbers between 10000000000 to 999999999999

[jonrsharpe]

Then use that, rather than trying to check the length.

[Sangwin Gawande]

So there is no default method for that? we'll have to create one to limit those?

[jonrsharpe]

What makes you say that? See angular.io/api/forms/Validators, which shows both min and max.

[Sangwin Gawande]

Thanks, My mistake, Just saw it, wrote it, and it worked. :)

[Tabish Zaman]

Ts File import { Component, OnInit } from '@angular/core'; import { FormBuilder, FormControl, FormGroup, ReactiveFormsModule, Validators } from '@angular/forms'; @Component({ selector: 'ftl-signup', templateUrl: './signup.component.html', styleUrls: ['./signup.component.scss'] }) export class PasswordChecker implements OnInit { validateForm: FormGroup; constructor(private fb: FormBuilder) { password: ['', [Validators.required, Validators.minLength(5), Validators.maxLength(15)]], }); }

[kara]

You should edit your answer instead of adding comments to your own answer.

[Coderer]

I know I'm a year late here, and it's not exactly what was asked in the OP, but nobody will want to enter a phone number as <input type='number'>. The answer under "Update 1" is correct for integers, but a phone number is not an integer. This isn't even the "falsehoods about phone numbers" piece I was looking for, but it has a lot of good points.

[Paco Zevallos]

Excellent worked perfect for me. A small detail is that when we declare minlength in the mat-error note that it is lowercase, while in the validator it is minLength with uppercase.

[Sangwin Gawande]

Why use extra event keyup when Angular can do it without it?

[aman raj]

I added keyup event to remove special characters or operators while entering otherwise its up to you to add keyup event or not

[Sangwin Gawande]

Using type="number" removes special characters, doesn't it?

[aman raj]

Yes it removes special characters in type= number but it will have + , - , e while entering . If you want to restrict these operators while entering use keyup event else everything is fine.

[Aymen TAGHLISSIA]

But with this soution you can add zeros on the left withour being controlled , maxlength(10) and max(999999999) are not the same -_-