react-addons-linked-state-mixin

Note: This is a legacy React addon, and is no longer maintained.

We don't encourage using it in new code, but it exists for backwards compatibility.
The recommended migration path is to explicitly set value and the onChange handler instead of using LinkedStateMixin.

Importing LinkedStateMixin

import LinkedStateMixin from 'react-addons-linked-state-mixin'; // ES6
var LinkedStateMixin = require('react-addons-linked-state-mixin'); // ES5 with npm

If you prefer a <script> tag, you can get it from React.addons.LinkedStateMixin with:

<!-- development version -->
<script src="https://unpkg.com/react-addons-linked-state-mixin/react-addons-linked-state-mixin.js"></script>

<!-- production version -->
<script src="https://unpkg.com/react-addons-linked-state-mixin/react-addons-linked-state-mixin.min.js"></script>

In this case, make sure to put the <script> tag after React.

Importing LinkedInput

After React 16, you will also need LinkedInput component if you want to keep using this pattern. You can import it like this:

import LinkedInput from 'react-linked-input'; // ES6
var LinkedInput = require('react-linked-input'); // ES5 with npm

If you prefer a <script> tag, you can get it from LinkedInput global with:

<!-- development version -->
<script src="https://unpkg.com/react-linked-input/react-linked-input.js"></script>

<!-- production version -->
<script src="https://unpkg.com/react-linked-input/react-linked-input.min.js"></script>

Overview

LinkedStateMixin is an easy way to express two-way binding with React.

In React, data flows one way: from owner to child. We think that this makes your app's code easier to understand. You can think of it as "one-way data binding."

However, there are lots of applications that require you to read some data and flow it back into your program. For example, when developing forms, you'll often want to update some React state when you receive user input. Or perhaps you want to perform layout in JavaScript and react to changes in some DOM element size.

In React, you would implement this by listening to a "change" event, read from your data source (usually the DOM) and call setState() on one of your components. "Closing the data flow loop" explicitly leads to more understandable and easier-to-maintain programs. See our forms documentation for more information.

Two-way binding -- implicitly enforcing that some value in the DOM is always consistent with some React state -- is concise and supports a wide variety of applications. We've provided LinkedStateMixin: syntactic sugar for setting up the common data flow loop pattern described above, or "linking" some data source to React state.

Note:

LinkedStateMixin is just a thin wrapper and convention around the onChange/setState() pattern. It doesn't fundamentally change how data flows in your React application.

LinkedStateMixin: Before and After

Here's a simple form example without using LinkedStateMixin:

var createReactClass = require('create-react-class');

var NoLink = createReactClass({
  getInitialState: function() {
    return {message: 'Hello!'};
  },
  handleChange: function(event) {
    this.setState({message: event.target.value});
  },
  render: function() {
    var message = this.state.message;
    return <input type="text" value={message} onChange={this.handleChange} />;
  }
});

This works really well and it's very clear how data is flowing, however, with a lot of form fields it could get a bit verbose. Let's use LinkedStateMixin to save us some typing:

var createReactClass = require('create-react-class');
var LinkedInput = require('react-linked-input');

var WithLink = createReactClass({
  mixins: [LinkedStateMixin],
  getInitialState: function() {
    return {message: 'Hello!'};
  },
  render: function() {
    return <LinkedInput type="text" valueLink={this.linkState('message')} />;
  }
});

LinkedStateMixin adds a method to your React component called linkState(). linkState() returns a valueLink object which contains the current value of the React state and a callback to change it. The LinkInput component passes those properties to the input it renders.

valueLink objects can be passed up and down the tree as props, so it's easy (and explicit) to set up two-way binding between a component deep in the hierarchy and state that lives higher in the hierarchy.

Note that checkboxes have a special behavior regarding their value attribute, which is the value that will be sent on form submit if the checkbox is checked (defaults to on). The value attribute is not updated when the checkbox is checked or unchecked. For checkboxes, you should use checkedLink instead of valueLink:

<LinkedInput type="checkbox" checkedLink={this.linkState('booleanValue')} />