FORMS TO GO COMPARE TWO FIELDS PASSWORD
FORMS TO GO COMPARE TWO FIELDS SERIES

The password field was configured in the way that you are probably the most used to, by using the FormBuilder API simplified array syntax: If you noticed, the validation rules for the email and the password fields were configured in a slightly different way.

Two alternative syntaxes for configuring validators Each form field has its own list of separate validators. So how do these validators work, what is a validator?Ī form field validator is a function that the form can call in order to decide if a given form field is valid or not.Ī validator function returns true if the form field is valid according to the validator rules, or false otherwise.Ī validator can be plugged in directly into a reactive form simply by adding it to the validators list. These are two examples of the several built-in validators that we have available to use, right out of the box. In this particular reactive form, we are using the FormBuilder API in order to define our form fields and validation rules in a concise way.įor example, the email field is marked as mandatory via the Validators.required validator, and it also needs to follow the format of a valid email, due to the use of the Validators.email validator. Let's go through them one at a time, starting with the simpler ones. There are a lot of validation rules being used here.

Here is the corresponding component class: We don't see any business validation rules because this is a reactive form, so all validation rules are defined on the component, and not on the template. Here is an example of a simple reactive form, with a couple of standard validators:Īs we can see, this is a simple login form with an email and password fields. a form validity state, which is true if all the form fields are valid, and false if at least one of the forms fields is invalidĮach form field has its own set of business validation rules: the fields can be mandatory, have a minimum length of 10 characters, etc.the form value, consisting of the values of all the individual form fields.If you have used either the Angular Forms or ReactiveForms modules, you will have noticed that every form has a couple of important properties: So without further ado, let's get started learning everything that we need to know to write our own custom form validators! What is a form field Validator?

FORMS TO GO COMPARE TWO FIELDS SERIES

This post is part of our ongoing series on Angular Forms, you can find all the articles available here.

Comparing validation in template-driven vs reactive forms.

Custom Validators for template-driven forms.

Displaying error messages for custom validators.

This post will cover the following topics: In this post, you will learn everything that you need to know in order to implement your own custom form validators, including both synchronous and asynchronous, field-level, form-level, and both for template-driven and reactive forms. When building large scale forms with the Angular Forms module, the available built-in validators (such as making a field required, etc.) usually won't be sufficient, and so you will have to develop your own custom form validation rules.

Forms to go compare two fields