Angular custom reactive forms validator doesn't work

Question

I'm trying to implement a custom angular validator for date range checking.

The validator itself works properly and returns a validation error. However, nothing seems to be happening at the client side - no errors are being shown and the form is considered to be valid. I've tried various changes to this code, with no joy.

Any ideas on what to try?

Html:

<div class="alert-danger" *ngIf="form.controls.creditCheckDate.errors?.dateRange">
    Date should be from 1/1/2000 to Today.
</div>

.ts:

const controlsConfig = {
    creditCheckDate: ['', [Validators.required,
                           CustomValidators.dateRange(new Date(2000, 1), new Date(Date.now()))]]
};

return this.fb.group(controlsConfig);

Validator:

static dateRange(minDate: Date | null, maxDate: Date | null): ValidatorFn {
    return (c: AbstractControl): ValidationErrors | null => {
        const validationError = { dateRange: true };

        if (!c.value) {
            return null;
        }

        const timestamp = Date.parse(c.value);
        if (isNaN(timestamp)) {
            return validationError;
        }

        const date = new Date(timestamp);
        if ((minDate && minDate > date) || (maxDate && maxDate < date)) {
            return validationError;
        }

        return null;
    };
}

@Kardon63 Thanks, unfortunately it still doesn't work. I tried to log the form into console on the control change event and the form is considered valid even though the validator returns error, so there's no error in the control. — Ivan Yurchenko

Siju Samson Siju Samson · Accepted Answer · 2020-06-25T17:58:30

Please have a look at my code.

HTML

<form [formGroup]="testForm">
  <div class="row">
    <div class="col-xs-12 col-12 col-md-4 form-group">
      <input
        type="text"
        placeholder="Datepicker"
        class="form-control"
        bsDatepicker
        formControlName = "date"
      />
    </div>
    <div *ngIf="testForm.controls.date.invalid && (submitted)" class="text-danger">
        <small *ngIf="testForm.controls.date.errors?.required">
           Date is required
         </small>
       <small *ngIf="testForm.controls.date.errors?.dateRange">
         Date is invalid
       </small>
     </div>
  </div>
  <button type="button" (click)="onSubmit()">Submit</button>
</form>

TS

 import { Component } from "@angular/core";
    import {
      AbstractControl,
      FormGroup,
      FormControl,
      ValidationErrors,
      ValidatorFn,
      Validators
    } from "@angular/forms";
    
    @Component({
      selector: "app-root",
      templateUrl: "./app.component.html",
      styleUrls: ["./app.component.css"]
    })
    export class AppComponent {
      testForm: FormGroup;
      submitted: boolean;
    
      constructor() {
        this.testForm = new FormGroup({
          date: new FormControl("", [Validators.required, this.dateRange(new Date(2000, 1), new Date(Date.now()))])
        });
        this.submitted = false;
      }
    
      dateRange(minDate: Date | null, maxDate: Date | null): ValidatorFn {
        return (c: AbstractControl): ValidationErrors | null => {
          const validationError = { dateRange: true };
    
          if (!c.value) {
            return null;
          }
    
          const timestamp = Date.parse(c.value);
          if (isNaN(timestamp)) {
            return validationError;
          }
    
          const date = new Date(timestamp);
          if ((minDate && minDate > date) || (maxDate && maxDate < date)) {
            return validationError;
          }
    
          return null;
        };
      }
    
      onSubmit() {
        this.submitted = true;
        console.log(this.testForm);
      }
    }

I have tried your code in code sandbox, and there it seems to work fine. https://codesandbox.io/s/suspicious-http-11288

Angular custom reactive forms validator doesn't work

2 Answers

HTML

TS