149 lines
4.5 KiB
Markdown
149 lines
4.5 KiB
Markdown
---
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id: 5a24c314108439a4d4036147
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title: Connect Redux to React
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challengeType: 6
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isRequired: false
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forumTopicId: 301426
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---
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## Description
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<section id='description'>
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Now that you've written both the <code>mapStateToProps()</code> and the <code>mapDispatchToProps()</code> functions, you can use them to map <code>state</code> and <code>dispatch</code> to the <code>props</code> of one of your React components. The <code>connect</code> method from React Redux can handle this task. This method takes two optional arguments, <code>mapStateToProps()</code> and <code>mapDispatchToProps()</code>. They are optional because you may have a component that only needs access to <code>state</code> but doesn't need to dispatch any actions, or vice versa.
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To use this method, pass in the functions as arguments, and immediately call the result with your component. This syntax is a little unusual and looks like:
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<code>connect(mapStateToProps, mapDispatchToProps)(MyComponent)</code>
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<strong>Note:</strong> If you want to omit one of the arguments to the <code>connect</code> method, you pass <code>null</code> in its place.
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</section>
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## Instructions
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<section id='instructions'>
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The code editor has the <code>mapStateToProps()</code> and <code>mapDispatchToProps()</code> functions and a new React component called <code>Presentational</code>. Connect this component to Redux with the <code>connect</code> method from the <code>ReactRedux</code> global object, and call it immediately on the <code>Presentational</code> component. Assign the result to a new <code>const</code> called <code>ConnectedComponent</code> that represents the connected component. That's it, now you're connected to Redux! Try changing either of <code>connect</code>'s arguments to <code>null</code> and observe the test results.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: The <code>Presentational</code> component should render.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); return mockedComponent.find('Presentational').length === 1; })());
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- text: The <code>Presentational</code> component should receive a prop <code>messages</code> via <code>connect</code>.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const props = mockedComponent.find('Presentational').props(); return props.messages === '__INITIAL__STATE__'; })());
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- text: The <code>Presentational</code> component should receive a prop <code>submitNewMessage</code> via <code>connect</code>.
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testString: assert((function() { const mockedComponent = Enzyme.mount(React.createElement(AppWrapper)); const props = mockedComponent.find('Presentational').props(); return typeof props.submitNewMessage === 'function'; })());
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='jsx-seed'>
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```jsx
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const addMessage = (message) => {
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return {
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type: 'ADD',
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message: message
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}
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};
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const mapStateToProps = (state) => {
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return {
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messages: state
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}
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};
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const mapDispatchToProps = (dispatch) => {
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return {
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submitNewMessage: (message) => {
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dispatch(addMessage(message));
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}
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}
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};
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class Presentational extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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return <h3>This is a Presentational Component</h3>
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}
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};
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const connect = ReactRedux.connect;
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// change code below this line
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```
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</div>
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### After Test
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<div id='jsx-teardown'>
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```js
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const store = Redux.createStore(
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(state = '__INITIAL__STATE__', action) => state
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);
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class AppWrapper extends React.Component {
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render() {
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return (
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<ReactRedux.Provider store = {store}>
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<ConnectedComponent/>
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</ReactRedux.Provider>
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);
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}
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};
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ReactDOM.render(<AppWrapper />, document.getElementById('root'))
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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const addMessage = (message) => {
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return {
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type: 'ADD',
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message: message
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}
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};
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const mapStateToProps = (state) => {
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return {
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messages: state
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}
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};
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const mapDispatchToProps = (dispatch) => {
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return {
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submitNewMessage: (message) => {
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dispatch(addMessage(message));
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}
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}
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};
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class Presentational extends React.Component {
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constructor(props) {
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super(props);
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}
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render() {
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return <h3>This is a Presentational Component</h3>
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}
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};
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const connect = ReactRedux.connect;
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// change code below this line
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const ConnectedComponent = connect(mapStateToProps, mapDispatchToProps)(Presentational);
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```
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</section>
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