Table of Contents

• Features
• Installation
• Usage
• License

Features

• Simple usage with help of higher-order component.
• You define your own validation rules.
• Support for both synchronous and asynchronous validations.
• Automatically validates every input inside a form. Even the ones nested into another component.
• Easy integration with UI frameworks.

Installation

npm

npm install feerzlay/react-form-validation --save

yarn

yarn add feerzlay/react-form-validation

Usage

Create a validator

This library does not contain any built-in validation rules. So before creating a validator you need to define you own rules. A rule is a function of following signature - (name, value, values, ..args). This function should return null on validation pass, and error message on validation fail. You can also return a Promise which resolves to null or String.

So, you can define your rules like this:

const rules = {
  required: (name, value) => {
    if (value.length > 0) return null;
    return '${name} can\'t be empty';
  },
  min: (name, value, values, min) => {
    if (value.length >= min) return null;
    return `${name} must be at least ${min} characters long`;
  }
};

Note that values agrument contains values of every validatable input inside a form. You can use it to define rules like a password confirmation.

Now you can import a validator creator and pass previously defined rules as an agrument:

import { createValidator } from '@feerzlay/react-form-validation';
const validator = createValidator(rules);

Create a higher-order component

This step is pretty simple. Just import a HOC creator and previously created validator as an agrument.

import { createValidatable } from '@feerzlay/react-form-validation';
const Validatable = createValidatable(validator);

Wrap your inputs

Wrap your inputs with created higher-order component.

const BasicInput = props => <input {...props} />;
const Input = Validatable(BasicInput);

Take a note that HOC expects input to recieve name and value props and emit onChange and onBlur values.

Create a Form component

For a basic usage you only need to import a form creator function and call it.

import { createForm } from '@feerzlay/react-form-validation';
const Form = createForm();

This function also accepts an object of options. For now this object have only one entry:

{ event: 'onChange' }

You can override it to be onBlur or just an empty string. If onBlur is used, then only form submit and input blur will trigger validation. If empty string is used, then only form submit will trigger validation.

Created component can be used almost as a regular <form> tag, but with two differences:

• onSubmit event triggered only on successful validation.
• It has an additional onErrorsChange event, which you should use to store information about errors and display them to the user.

Done :tada:

Now when you have form and input components you are ready to start building your forms.

<Form onSubmit={...} onErrorsChange={...}>
  <Input
    value={...} onChange={...} name="username"
    validate="required"
  />
  <Input
    value={...} onChange={...} name="password"
    validate="required|min:8"
  />
  <Input
    value={...} onChange={...} name="optional"
  />
</Form>

We use validate prop do describe which rules must be used for input validation. Individual rules should be separated by |. To pass agruments use : and then write a list of arguments separated by ,.

You can also manually add and remove errors from inputs by calling addError({ name, error }) and removeError(name) methods on a form component.

See example for more usage details.

License

MIT - Denis Yakshov - 2018