react-validation

Component to provide simple form validation for React components. It uses the Controlled Components approach for validation.

It is not easy to validate forms with React. The reason is a one-way data flow style. In this case we can't affect forms from the inputs in an easy way. React-validation provides several components which are 'connected' to the form via the input's method attached by the Form component.

DEMO

DEMO src

It is just a validation and doesn't provide any model or something similar. You can use FormData or something like form-serialize to get form data.

NOTE: Always pass the name props. It's required.

Any additional props (such as event handlers) can also be passed to components.

If you find any bug or error, please feel free to raise an issue. Pull requests are also welcome.

Installation

npm install react-validation

Test

npm test

Example usage

First of all let's define some validations:

import validator from 'validator';
const required = (value) => {
  if (!value.toString().trim().length) {
    // We can return string or jsx as the 'error' prop for the validated Component
    return 'require';
  }
};

const email = (value) => {
  if (!validator.isEmail(value)) {
    return `${value} is not a valid email.`
  }
};

const lt = (value, props) => {
  // get the maxLength from component's props
  if (!value.toString().trim().length > props.maxLength) {
    // Return jsx
    return <span className="error">The value exceeded {props.maxLength} symbols.</span>
  }
};

const password = (value, props, components) => {
  // NOTE: Tricky place. The 'value' argument is always current component's value.
  // So in case we're 'changing' let's say 'password' component - we'll compare it's value with 'confirm' value.
  // But if we're changing 'confirm' component - the condition will always be true
  // If we need to always compare own values - replace 'value' with components.password[0].value and make some magic with error rendering.
  if (value !== components['confirm'][0].value) { // components['password'][0].value !== components['confirm'][0].value
    // 'confirm' - name of input
    // components['confirm'] - array of same-name components because of checkboxes and radios
    return <span className="error">Passwords are not equal.</span>
  }
};

That's it. We can now use it in our React components:

import Form from 'react-validation/build/form';
import Input from 'react-validation/build/input';
import React, { Component } from 'react';

export default class Login extends Component {
    render() {
        return <Form>
            <h3>Login</h3>
            <div>
                <label>
                    Email*
                    <Input value='[email protected]' name='email' validations={[required, email]}/>
                </label>
            </div>
            <div>
                <label>
                    Password*
                    <Input type='password' name='password' validations={[required]}/>
                </label>
            </div>
            <div>
                <Button>Submit</Button>
            </div>
        </Form>;
    }
}

Note the validations prop. It's an array of functions which was defined earlier.

Components and props

react-validation provides a components with pre-defined structure and hocs to define it self. The components are: Form, Input, Select, Textarea and Button. All of them are just custom wrappers around the native components. They can accept any valid attributes and a few extra:

1. isUsed - Input, Select and Textarea: says to react-validation to mark component as it was blured.
2. isChanged - Input, Select and Textarea: says to react-validation to mark component as it was changed.
3. validations - Input, Select and Textarea: accepts an array of validations functions.

NOTE: Always provide a name prop to Input, Select and Textarea.

Form component

Form

The most important component, which provides the heart of react-validation. It basically mixes the binding between the form itself and child react-validation components via context. Any valid props can easily be passed to Form, such onSubmit and method.

Form provides four public methods:

1. validate(name) - validates control(s) with the passed name. The difference between this method and default validation is that validate marks the input as isUsed and isChanged. name - name of the corresponding component(s).

2. validateAll() - validates all controls by marking all controls as isUsed and isChanged.

3. showError(component [,error]) - helps to handle async API errors. component - ref to the React Component to validate. error - error to show. Can be string or jsx.

4. hideError(component) - hides a corresponding component's error. component - ref to the React Component.

export default class Comment extends Component {
    handleSubmit = (event) => {
        event.preventDefault();

        // Emulate async API call
        setTimeout(() => {
            this.form.showError(this.userInput, <span>API error</span>);
        }, 1000);
    };

    removeApiError = () => {
        this.form.hideError(this.userInput);
    };

    render() {
        return <Form ref={c => { this.form = c }} onSubmit={this.handleSubmit.bind(this)}>
            <div className="row">
                <div className="small-12 columns">
                    <h3>Leave a comment</h3>
                </div>
            </div>
            <div className="row">
                <div className="small-12 medium-4 columns">
                    <label>
                        <Input
                          onFocus={this.removeApiError}
                          ref={c => { this.userInput = c }}
                          placeholder="username"
                          type="text"
                          value="Username"
                          name="username"
                          validations={[required]}
                        />
                    </label>
                </div>
                <div className="small-12 medium-8 columns">
                    <label>
                        <Textarea
                          placeholder="Leave your comment..."
                          value="Comment"
                          name="comment"
                          validations={[required]}
                        />
                    </label>
                </div>
            </div>
            <div className="row">
                <div className="small-12 medium-6 columns">
                    <Button className="button">Submit</Button>
                </div>
            </div>
        </Form>
    }
}

HOCs

react-validations also provides HOC (High Order Component) for each component. That made to have an ability to define own render logic, use mixed props, etc.

import { form, control, button } from 'react-validation';

// Define own Form component
const Form = ({ getValues, validate, validateAll, showError, hideError, children, ...props }) => ( // destruct non-valid props
  <form {...props}>{children}</form>
);

// Define own Input component
const Input = ({ error, isChanged, isUsed, ...props }) => (
  <div>
    <input {...props} />
    {isChanged && isUsed && error}
  </div>
);

// Define own Button component
const Button = ({ hasErrors, ...props }) => {
  return (
    <button {...props} disabled={hasErrors} />
  );
};

// Now call HOCs on components
const MyValidationForm = form(Form);
const MyValidationInput = control(Input);
const MyValidationButton = button(Button);

That's it. Now MyValidationForm can be used with all given API.

props

form:

getValues - function which returns object with keys by 'name' prop and string values. NOTE: same-name controls will be returned as array of strings. validate(name) - function to validate controls by 'name' argument. It marks control as 'isUsed' and 'isBlured'. showError(component, [,error]) - function to force showing error. component - ref to the control, error - string/jsx. hideError(component) - function to hide error on passed control ref.

control:

error - string or jsx. Note that error will be defined anytime the control has invalid value. Use isUsed and isChanged to apply rendering logic. isChanged - boolean. Indicates the control was changed. isUsed - boolean. Indicates the control was blurd.

button:

hasErrors - boolean. Indicates the whole form contain at least one invalid control.

Input component

Input

A wrapper around the native input. It accepts a validations prop - an array of functions.

<Input name='firstname' validations={[lt8, alpha]}/>

react-validation will break with the first listed rule, if more than one rule is broken. In the example above (lt8 - value length less than 8), for really long value with d1g1t input value, the alpha rule will break validation first. We can control it by ordering rules within the validations array.

Textarea component

Textarea

A wrapper around the native textarea. Like Input, it accepts a validations prop. Nothing special here:

<Textarea name='comment' validations={[required]}/>

Select component

Select

A wrapper around the native select. Like Input, it accepts a validations prop. Nothing special here:

<Select name='city' value='' validations={[required]}>
    <option value=''>Choose your city</option>
    <option value='1'>London</option>
    <option value='2'>Kyiv</option>
    <option value='3'>New York</option>
</Select>

Button component

Button

A wrapper around the native button. React-validation disables (adds disabled prop) the button on error occurrences.