I don’t know if everybody has read this: https://medium.com/@stowball/a-dummys-guide-to-redux-and-thunk-in-react-d8904a7005d3?source=linkShare-36723b3116b2-1502668727 but it basically teaches you how to handle one API requests with redux and redux thunk. It’s a great guide, but I wonder what if my React component is having more than just one get request to a server? Like this:
componentDidMount() {
axios.get('http://localhost:3001/customers').then(res => {
this.setState({
res,
customer: res.data
})
})
axios.get('http://localhost:3001/events').then(res => {
this.setState({
res,
event: res.data
})
})
axios.get('http://localhost:3001/locks').then(res => {
this.setState({
res,
lock: res.data
})
})
}
I've been googling like crazy and I think I've made some progress, my action creator currently looks like this (don't know if its 100% correct):
const fetchData = () => async dispatch => {
try {
const customers = await axios.get(`${settings.hostname}/customers`)
.then(res) => res.json()
const events = await axios.get(`${settings.hostname}/events`)
.then(res) => res.json()
const locks = await axios.get(`${settings.hostname}/locks`)
.then(res) => res.json()
dispatch(setCustomers(customers))
dispatch(setEvents(events))
dispatch(setLocks(locks))
} catch(err) => console.log('Error', err)
}
So the next step is to create your reducers, I just made one:
export function events(state = initialState, action) {
switch (action.type) {
case 'EVENTS_FETCH_DATA_SUCCESS':
return action.events;
default:
return state;
}
}
I don't know how to handle this inside of my component now. If you follow the article ( https://medium.com/@stowball/a-dummys-guide-to-redux-and-thunk-in-react-d8904a7005d3?source=linkShare-36723b3116b2-1502668727) it will end up like this:
componentDidMount() {
this.props.fetchData('http://localhost:3001/locks')
}
And
Doors.propTypes = {
fetchData: PropTypes.func.isRequired,
doors: PropTypes.object.isRequired
}
const mapStateToProps = state => {
return {
doors: state.doors
}
}
const mapDispatchToProps = dispatch => {
return {
fetchData: url => dispatch(doorsFetchData(url))
}
}
export default connect(mapStateToProps, mapDispatchToProps)(Doors)
So my question is how should I handle my multiple get requests inside of my component now? Sorry if this questions seems lazy, but I really can't figure it out and I've really been trying to.
All help is super appreciated!!
One way I can think of to make that work is to move both API queries into reducers, and then dispatch actions whenever I want to a) get all items; and b) delete an item. Upon successful completion of those API operations, the reducer will update the store and the ItemList will re-render.
Redux Async Data Flow Just like with a normal action, we first need to handle a user event in the application, such as a click on a button. Then, we call dispatch() , and pass in something, whether it be a plain action object, a function, or some other value that a middleware can look for.
Your events
reducer should look more like:
export function events(state = initialState, action) {
switch (action.type) {
case 'EVENTS_FETCH_DATA_SUCCESS':
return Object.assign({}, state, {events: action.events});
default:
return state;
}
}
Or if you have the object spread transform, you can do:
case 'EVENTS_FETCH_DATA_SUCCESS':
return {...state, events: action.events};
You should always make your reducers pure functions, and one of the requirements of a pure function is that it doesn't modify its inputs directly. You need to return a new state object, with your changes merged in.
After making this change, you'll want a similar reducer for your other actions (customers, locks).
You also have syntax errors in your thunk:
1) .then(res) => res.json()
should be:
.then(res => res.json())
2) catch(err) => console.log('Error', err)
should be:
catch(err) {
console.error('Error', err)
}
You're already on the right track in your component. I imagine you have components Customers
and Locks
to go along with your Doors
component.
But why is it that you want to group your API requests and perform them sequentially? Unless each subsequent request needs data from the previous response, you can do them in parallel and reduce latency.
Then, since your reducers are writing the response to the state, and your mapStateToProps
, well... maps the state to your props, you can simply read from this.props.doors
inside your render
method. If you want to show a loader while you're waiting for your props to populate with actual values, you can add some conditional logic like:
render() {
const { doors } = this.props;
return (
<div className="Doors">
{doors === null
? this.renderLoader()
: this.renderDoors()
}
</div>
);
}
renderLoader() {
return <Loader/>;
}
renderDoors() {
const { doors } = this.props;
return doors.map(door => (
<Door key={door.id}/>
));
}
Now when Doors
is rendered, in componentDidMount
you can call your original fetchData
and your component will automatically be re-rendered when the doors
prop changes. The same goes for each other component; when they mount, they request new data, and when the data arrives, your thunk dispatches a store update, and your component's props change in response to that update.
Let's say your API flow is actually complicated enough that it requires each API request to know some data from the previous request, like if you're fetching a customer's favorite brand of door, but the fetchCustomer
endpoint only returns you favoriteDoorID
, so you have to call fetchDoor(favoriteDoorID)
.
Now you have a real use case for your combined thunk, which would look something like:
const fetchFavoriteDoorForCustomer = (customerID) => async dispatch => {
try {
const customer = await axios.get(`${settings.hostname}/customer/${customerID}`)
.then(res => res.json());
const doorID = customer.favoriteDoorID;
const favoriteDoor = await axios.get(`${settings.hostname}/door/${doorID}`)
.then(res => res.json());
dispatch(receivedFavoriteDoor(favoriteDoor));
} catch(err) {
console.error('Error', err);
}
}
You would then create a case in one of your reducers, listening for the action type RECEIVED_FAVORITE_DOOR
or some such, which would merge it into the state like written in my first section.
And finally the component which requires this data would be subscribed to the store using connect
, with the appropriate mapStateToProps
function:
const mapStateToProps = state => {
return {
favoriteDoor: state.favoriteDoor
}
}
So now you can just read from this.props.favoriteDoor
, and you're good to go.
Hope that helps.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With