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[Angular2 Form] Model Driven Form Custom Validator

2024-08-18 01:37:37   218人阅读

In this tutorial we are going to learn how simple it is to create custom form field driven validators while using Angular 2 model driven forms. These type of validators are really just plain functions that follow a set of conventions.

We are going to learn how to write a custom form validator and what the validating function needs to return in order to respect the Angular 2 form field validation contract.

 

Define a custom validator:

import {FormControl} from "@angular/forms";export function validateDuration(ctrl:FormControl){    const numValue =http://www.mamicode.com/ parseInt(ctrl.value);  const valid = numValue < 10;  return valid ? null : {    validateDuration: {      valid: false,      message: "Duration should less than 10"    }  }}

It just a function which return null or object, is it has error, it should return an object. 

 

this.reactiveForm = fb.group({      ...      duration: [        0,        [          Validators.required,          //Validators.pattern(‘[0-9]+‘),          validateDuration        ]      ],      ...    });

We add ‘validateDuration‘ into our validators array.

 

Use it:

  <div class="form-field">    <label>Duration:</label>    <input formControlName="duration">    <div *ngIf="reactiveForm.controls.duration.errors?.validateDuration">       {{reactiveForm.controls.duration.errors?.validateDuration.message}}    </div>  </div>

 

[Angular2 Form] Model Driven Form Custom Validator


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