I would like to have a component, which get the property from parent component and make an AJAX request, based on this propery. The parent component can change this property and my child component must get another one AJAX request.
Here is my code, but I am not sure it is optimal and even correct:
<News source={this.state.currentSource} />
Component:
var News = React.createClass({
propTypes: {
source: React.PropTypes.string
},
getInitialState: function() {
return {
entities: []
};
},
componentWillReceiveProps(nextProps) {
var url = 'http://localhost:3000/api/sources/' + nextProps.source + '/news';
this.serverRequest = $.get(url, function(result) {
this.setState({
entities: result
});
}.bind(this));
},
componentWillUnmount: function() {
this.serverRequest.abort();
},
render: function() {
// ...
}});
module.exports = News;
Does componentWillReceiveProps is a good place for this code?
componentWillReceiveProps will work just fine, one thing I would do differently is if <News/> is getting its props from a parent component then a good pattern to follow is to have the parent component actually handle the api calls and pass down the results as props. This way your News component really only has to deal with rendering content based on its props vs rendering and managing state.
I can only see limited portion of your App so that might not fit your use case but here is a great article on doing that type of differentiation between smart and dumb components.
http://jaketrent.com/post/smart-dumb-components-react/
I have a RefluxJS application which has several stores and a pretty deep component hierarchy. I've tried to make the components very independent, with each connecting to the stores it needs to render; and the stores themselves sometimes call Actions that other stores listen to.
I've found that I get a lot of spurious calls to my components' render() methods, because two stores might listen to the same action, and different components in the hierarchy might listen to those different stores. This is affecting the user experience because sometimes there's a little bit of lag.
Here's some code:
var Actions = Reflux.createActions(['changeUser']);
Actions.changeUser.preEmit = () => console.log('Action emit: changeUser');
var UserStore = Reflux.createStore({
listenables: [Actions],
onChangeUser(user) {
this.trigger(user);
}
});
var MessageStore = Reflux.createStore({
listenables: [Actions],
onChangeUser(user) {
setTimeout(() => {
// pretend we had to go to an API or something to get this
var message = "Welcome to the app!";
this.trigger(message);
}, 500);
},
});
var App = React.createClass({
mixins: [Reflux.connect(UserStore, 'user')],
render() {
console.log('Component render: App');
if (!this.state.user) {
return (
<button onClick={() => Actions.changeUser('Some User')}>
Click to make stuff happen
</button>
);
}
return (
<div>
<div>Hello, {this.state.user}.</div>
<Message / >
</div>
);
}
});
var Message = React.createClass({
mixins: [Reflux.connect(MessageStore, 'message')],
render() {
console.log('Component render: Message');
return <div>Your message: {this.state.message}</div>;
}
});
ReactDOM.render( <App/> , document.getElementById('app'));
Fiddle: https://jsfiddle.net/9xwnxos6/
This is way oversimplified (in this example I'd probably just add a loading indicator of some kind), but illustrates the basic issue that you can see the UI sort of transitioning through intermediate states while you're doing things.
How can I improve my React/Reflux design in order to avoid multiple renders triggering from a single interaction?
It seems my issues are coming from violating a couple of good React/Flux practices:
Don't trigger Actions from within a Store
Only connect to Stores in high-level components
I am refactoring to get the Store connections out of the low-level components. I'm not crazy about this, because it means I have to pass all kinds of props through these deep component hierarchies to get them where they need to be. But it seems that is the "right" way to build a Reflux app.
If no one else posts an answer within the next few days, I will accept this one.
For simplification, I have a a component, that includes a subcomponent. The top parent component is the only stateful compontent. But the state of this needs to be set on children deep within. How can these children access the state of the top most parent?
Is passing the state down via props the only way? I ask because I have a comonent that has many children deep down, so to access state I would have to pass state as a prop to 5 levels, just so 5th level can access state.
For a simplified example:
var Timer = React.createClass({
getInitialState: function() {
return {secondsElapsed: 0};
},
tick: function() {
this.setState({secondsElapsed: this.state.secondsElapsed + 1});
},
componentDidMount: function() {
this.interval = setInterval(this.tick, 1000);
},
componentWillUnmount: function() {
clearInterval(this.interval);
},
render: function() {
return (
<Label />
);
}
});
var Label = React.createClass({
render: function() {
return (
<div>Seconds Elapsed: {this.state.secondsElapsed}</div>
);
}
});
ReactDOM.render(<Timer />, mountNode);
This example gives this.state is null
There are in general two well accepted ways to do this.
Indeed pass the properties down the tree of components. This can sometimes work very well, and is something I personally use a lot for more UI work in the components, like making sure a pagination works generically all over the app (total pages, currentpage, items per page). For more app 'state' kind of things this is generally not the right approach
Switch to something to manage your application state, like Flux, which will help you with the concept of a store to keep this state in, if both components need this. I use the alt implementation, but Facebook's official and other ones are also very well known.
In general I'd advise you to dive a bit into some videos of React and Flux, perhaps the ones where people show you how they do certain things like this. For example this one.
You can pass the state down to an arbitrary depth by using a slightly experimental feature of react called "contexts".
They have a page detailing it. Head the warning at the top, as this should be used for special circumstances only.
Try to perhaps refactor or think ahead when using contexts, as they can lead your to create subcomponents which assume certain contexts, which limits their reusability.
I've read on http://scotch.io/tutorials/javascript/build-a-real-time-twitter-stream-with-node-and-react-js and it describes a technique of taking over server rendered React components seamlessly:
Server renders into {{{markup}}} in handlebars, and pass initial state.
<section id="react-app">{{{ markup }}}</div>
<script id="initial-state" type="application/json">{{{state}}}</script>
Then on the client side javascript
/** #jsx React.DOM */
var React = require('react');
var TweetsApp = require('./components/TweetsApp.react');
// Snag the initial state that was passed from the server side
var initialState = JSON.parse(document.getElementById('initial-state').innerHTML)
// Render the components, picking up where react left off on the server
React.renderComponent(
<TweetsApp tweets={initialState}/>,
document.getElementById('react-app')
);
But in a flux architecture, such as described in this article http://scotch.io/tutorials/javascript/creating-a-simple-shopping-cart-with-react-js-and-flux, state is initialized in the getInitialState lifecycle method:
// Method to retrieve state from Stores
function getCartState() {
return {
product: ProductStore.getProduct(),
selectedProduct: ProductStore.getSelected(),
cartItems: CartStore.getCartItems(),
cartCount: CartStore.getCartCount(),
cartTotal: CartStore.getCartTotal(),
cartVisible: CartStore.getCartVisible()
};
}
// Define main Controller View
var FluxCartApp = React.createClass({
// Get initial state from stores
getInitialState: function() {
return getCartState();
},
// Add change listeners to stores
componentDidMount: function() {
ProductStore.addChangeListener(this._onChange);
CartStore.addChangeListener(this._onChange);
},
// Remove change listers from stores
componentWillUnmount: function() {
ProductStore.removeChangeListener(this._onChange);
CartStore.removeChangeListener(this._onChange);
},
// Render our child components, passing state via props
render: function() {
return (
<div className="flux-cart-app">
<FluxCart products={this.state.cartItems} count={this.state.cartCount} total={this.state.cartTotal} visible={this.state.cartVisible} />
<FluxProduct product={this.state.product} cartitems={this.state.cartItems} selected={this.state.selectedProduct} />
</div>
);
},
// Method to setState based upon Store changes
_onChange: function() {
this.setState(getCartState());
}
});
module.exports = FluxCartApp;
Which one is the right approach to setting state from a progressive enhancement point of view?
Thinking about progressive enhancement I like how flux and react work together.
I am using ReactJS and Flux in my current project and everything is clean and easy. All you have to be aware of is showing some discipline of creating new stores when it really is needed. I dont really like the eventEmitter stuff though. I just trigger my own events which I define in a seperate eventConstants.js file this allows me to have several components listening for different changes on the same store.
This really scales well.
Answering your question:
It does depend about your usecase. Ignoring that rendering an initial page on the server is great for SEO it does only make sence to render on the server if users should all see pretty much the same content. I like to keep client stuff on the client.
I hope this helped you
This may be treading that line between answerable and opinionated, but I'm going back and forth as to how to structure a ReactJS component as complexity grows and could use some direction.
Coming from AngularJS, I want to pass my model into the component as a property and have the component modify the model directly. Or should I be splitting the model up into various state properties and compiling it back together when sending back upstream? What is the ReactJS way?
Take the example of a blog post editor. Trying to modify the model directly ends up looking like:
var PostEditor = React.createClass({
updateText: function(e) {
var text = e.target.value;
this.props.post.text = text;
this.forceUpdate();
},
render: function() {
return (
<input value={this.props.post.text} onChange={this.updateText}/>
<button onClick={this.props.post.save}/>Save</button>
);
}
});
Which seems wrong.
Is it more the React way to make our text model property state, and compile it back into the model before saving like:
var PostEditor = React.createClass({
getInitialState: function() {
return {
text: ""
};
},
componentWillMount: function() {
this.setState({
text: this.props.post.text
});
},
updateText: function(e) {
this.setState({
text: e.target.value
});
},
savePost: function() {
this.props.post.text = this.state.text;
this.props.post.save();
},
render: function() {
return (
<input value={this.state.text} onChange={this.updateText}/>
<button onClick={this.savePost}/>Save</button>
);
}
});
This doesn't require a call to this.forceUpdate(), but as the model grows, (a post may have an author, subject, tags, comments, ratings, etc...) the component starts getting really complicated.
Is the first method with ReactLink the way to go?
Updating 2016:
React is changed, and explanation "props vs state" became very simple. If a component needs to change data - put it in a state, otherwise in props. Because props are read-only now.
What's the exact difference between props and state?
You can find good explanation here (full version)
Your second approach is more like it. React doesn't care about models so much as it cares about values and how they flow through your app. Ideally, your post model would be stored in a single component at the root. You then create child components that each consume parts of the model.
You can pass callbacks down to the children that need to modify your data, and call them from the child component.
Modifying this.props or this.state directly is not a good idea, because React will not be able to pick up on the changes. That's because React does a shallow comparison of your post prop to determine if it has changed.
I made this jsfiddle to show how data could flow from an outer to an inner component.
The handleClick method shows 3 ways to (im)properly update state:
var Outer = React.createClass({
getInitialState: function() {
return {data: {value: 'at first, it works'}};
},
handleClick: function () {
// 1. This doesn't work, render is not triggered.
// Never set state directly because the updated values
// can still be read, which can lead to unexpected behavior.
this.state.data.value = 'but React will never know!';
// 2. This works, because we use setState
var newData = {value: 'it works 2'};
this.setState({data: newData});
// 3. Alternatively you can use React's immutability helpers
// to update more complex models.
// Read more: http://facebook.github.io/react/docs/update.html
var newState = React.addons.update(this.state, {
data: {value: {$set: 'it works'}}
});
this.setState(newState);
},
render: function() {
return <Inner data={this.state.data} handleClick={this.handleClick} />;
}
});
From React doc
props are immutable: they are passed from the parent and are "owned" by the parent. To implement interactions, we introduce mutable state to the component. this.state is private to the component and can be changed by calling this.setState(). When the state is updated, the component re-renders itself.
From TrySpace: when props (or state) are updated (via setProps/setState or parent) the component re-renders as well.
A reading from Thinking in React:
Let's go through each one and figure out which one is state. Simply
ask three questions about each piece of data:
Is it passed in from a parent via props? If so, it probably isn't
state.
Does it change over time? If not, it probably isn't state.
Can you compute it based on any other state or props in your
component? If so, it's not state.
I'm not sure if I'm answering your question, but I've found that, especially in a large/growing application, the Container/Component pattern works incredibly well.
Essentially you have two React components:
a "pure" display component, which deals with styling and DOM interaction;
a container component, which deals with accessing/saving external data, managing state, and rendering the display component.
Example
N.B. This example is a probably too simple to illustrate the benefits of this pattern, as it is quite verbose for such a straightforward case.
/**
* Container Component
*
* - Manages component state
* - Does plumbing of data fetching/saving
*/
var PostEditorContainer = React.createClass({
getInitialState: function() {
return {
text: ""
};
},
componentWillMount: function() {
this.setState({
text: getPostText()
});
},
updateText: function(text) {
this.setState({
text: text
});
},
savePost: function() {
savePostText(this.state.text);
},
render: function() {
return (
<PostEditor
text={this.state.text}
onChange={this.updateText.bind(this)}
onSave={this.savePost.bind(this)}
/>
);
}
});
/**
* Pure Display Component
*
* - Calculates styling based on passed properties
* - Often just a render method
* - Uses methods passed in from container to announce changes
*/
var PostEditor = React.createClass({
render: function() {
return (
<div>
<input type="text" value={this.props.text} onChange={this.props.onChange} />
<button type="button" onClick={this.props.onSave} />
</div>
);
}
});
Benefits
By keeping display logic and data/state management separate, you have a re-usable display component which:
can easily be iterated with different sets of props using something like react-component-playground
can be wrapped with a different container for different behavior (or combine with other components to build larger parts of your application
You also have a container component which deals with all external communication. This should make it easier to be flexible about the way you access your data if you make any serious changes later on*.
This pattern also makes writing and implementing unit tests a lot more straightforward.
Having iterated a large React app a few times, I've found that this pattern keeps things relatively painless, especially when you have larger components with calculated styles or complicated DOM interactions.
*Read up on the flux pattern, and take a look at Marty.js, which largely inspired this answer (and I have been using a lot lately) Redux (and react-redux), which implement this pattern extremely well.
Note for those reading this in 2018 or later:
React has evolved quite a bit since this answer was written, especially with the introduction of Hooks. However, the underlying state management logic from this example remains the same, and more importantly, the benefits that you get from keeping your state and presentation logic separate still apply in the same ways.
I think you're using an anti-pattern which Facebook has already explained at this link
Here's thing you're finding:
React.createClass({
getInitialState: function() {
return { value: { foo: 'bar' } };
},
onClick: function() {
var value = this.state.value;
value.foo += 'bar'; // ANTI-PATTERN!
this.setState({ value: value });
},
render: function() {
return (
<div>
<InnerComponent value={this.state.value} />
<a onClick={this.onClick}>Click me</a>
</div>
);
}
});
The first time the inner component gets rendered, it will have { foo: 'bar' } as the value prop. If the user clicks on the anchor, the parent component's state will get updated to { value: { foo: 'barbar' } }, triggering the re-rendering process of the inner component, which will receive { foo: 'barbar' } as the new value for the prop.
The problem is that since the parent and inner components share a reference to the same object, when the object gets mutated on line 2 of the onClick function, the prop the inner component had will change. So, when the re-rendering process starts, and shouldComponentUpdate gets invoked, this.props.value.foo will be equal to nextProps.value.foo, because in fact, this.props.value references the same object as nextProps.value.
Consequently, since we'll miss the change on the prop and short circuit the re-rendering process, the UI won't get updated from 'bar' to 'barbar'