I want to call useQuery whenever I need it,
but useQuery can not inside the function.
My trying code is:
export const TestComponent = () => {
...
const { data, loading, error } = useQuery(gql(GET_USER_LIST), {
variables: {
data: {
page: changePage,
pageSize: 10,
},
},
})
...
...
const onSaveInformation = async () => {
try {
await updateInformation({...})
// I want to call useQuery once again.
} catch (e) {
return e
}
}
...
How do I call useQuery multiple times?
Can I call it whenever I want?
I have looked for several sites, but I could not find a solutions.
From apollo docs
When React mounts and renders a component that calls the useQuery hook, Apollo Client automatically executes the specified query. But what if you want to execute a query in response to a different event, such as a user clicking a button?
The useLazyQuery hook is perfect for executing queries in response to
events other than component rendering
I suggest useLazyQuery. In simple terms, useQuery will run when your component get's rendered, you can use skip option to skip the initial run. And there are some ways to refetch/fetch more data whenever you want. Or you can stick with useLazyQuery
E.g If you want to fetch data when only user clicks on a button or scrolls to the bottom, then you can use useLazyQuery hook.
useQuery is a declarative React Hook. It is not meant to be called in the sense of a classic function to receive data. First, make sure to understand React Hooks or simply not use them for now (90% of questions on Stackoverflow happen because people try to learn too many things at once). The Apollo documentation is very good for the official react-apollo package, which uses render props. This works just as well and once you have understood Apollo Client and Hooks you can go for a little refactor. So the answers to your questions:
How do I call useQuery multiple times?
You don't call it multiple times. The component will automatically rerender when the query result is available or gets updated.
Can I call it whenever I want?
No, hooks can only be called on the top level. Instead, the data is available in your function from the upper scope (closure).
Your updateInformation should probably be a mutation that updates the application's cache, which again triggers a rerender of the React component because it is "subscribed" to the query. In most cases, the update happens fully automatically because Apollo will identify entities by a combination of __typename and id. Here's some pseudocode that illustrates how mutations work together with mutations:
const GET_USER_LIST = gql`
query GetUserList {
users {
id
name
}
}
`;
const UPDATE_USER = gql`
mutation UpdateUser($id: ID!, $name: String!) {
updateUser(id: $id, update: { name: $name }) {
success
user {
id
name
}
}
}
`;
const UserListComponen = (props) => {
const { data, loading, error } = useQuery(GET_USER_LIST);
const [updateUser] = useMutation(UPDATE_USER);
const onSaveInformation = (id, name) => updateUser({ variables: { id, name });
return (
// ... use data.users and onSaveInformation in your JSX
);
}
Now if the name of a user changes via the mutation Apollo will automatically update the cache und trigger a rerender of the component. Then the component will automatically display the new data. Welcome to the power of GraphQL!
There's answering mentioning how useQuery should be used, and also suggestions to use useLazyQuery. I think the key takeaway is understanding the use cases for useQuery vs useLazyQuery, which you can read in the documentation. I'll try to explain it below from my perspective.
useQuery is "declarative" much like the rest of React, especially component rendering. This means you should expect useQuery to be called every render when state or props change. So in English, it's like, "Hey React, when things change, this is what I want you to query".
for useLazyQuery, this line in the documentation is key: "The useLazyQuery hook is perfect for executing queries in response to events other than component rendering". In more general programming speak, it's "imperative". This gives you the power to call the query however you want, whether it's in response to state/prop changes (i.e. with useEffect) or event handlers like button clicks. In English, it's like, "Hey React, this is how I want to query for the data".
You can use fetchMore() returned from useQuery, which is primarily meant for pagination.
const { loading, client, fetchMore } = useQuery(GET_USER_LIST);
const submit = async () => {
// Perform save operation
const userResp = await fetchMore({
variables: {
// Pass any args here
},
updateQuery(){
}
});
console.log(userResp.data)
};
Read more here: fetchMore
You could also use useLazyQuery, however it'll give you a function that returns void and the data is returned outside your function.
const [getUser, { loading, client, data }] = useLazyQuery(GET_USER_LIST);
const submit = async () => {
const userResp = await getUser({
variables: {
// Pass your args here
},
updateQuery() {},
});
console.log({ userResp }); // undefined
};
Read more here: useLazyQuery
You can create a reusable fetch function as shown below:
// Create query
const query = `
query GetUserList ($data: UserDataType){
getUserList(data: $data){
uid,
first_name
}
}
`;
// Component
export const TestComponent (props) {
const onSaveInformation = async () => {
// I want to call useQuery once again.
const getUsers = await fetchUserList();
}
// This is the reusable fetch function.
const fetchUserList = async () => {
// Update the URL to your Graphql Endpoint.
return await fetch('http://localhost:8080/api/graphql?', {
method: 'POST',
headers: {
'Content-Type': 'application/json',
'Accept': 'application/json',
},
body: JSON.stringify({
query,
variables: {
data: {
page: changePage,
pageSize: 10,
},
},
})
}).then(
response => { return response.json(); }
).catch(
error => console.log(error) // Handle the error response object
);
}
return (
<h1>Test Component</h1>
);
}
Here's an alternative that worked for me:
const { refetch } = useQuery(GET_USER_LIST, {
variables: {
data: {
page: changePage,
pageSize: 10,
},
},
}
);
const onSaveInformation = async () => {
try {
await updateInformation({...});
const res = await refetch({ variables: { ... }});
console.log(res);
} catch (e) {
return e;
}
}
And here's a similar answer for a similar question.
Please use
const { loading, data, refetch } = useQuery(Query_Data)
and call it when you need it i.e
refetch()
Related
I am trying to covert the following to hooks, but however I am getting some issues to translate this line this.fetchPlaces = debounce(this.fetchPlaces, 200); what is the exact match for hooks?
state = {
q: '',
places: [],
}
fetchPlaces(q) {
get(`http://www.example.com/places/`, {
params: {q}
}).then(response => {
this.setState({places: response.data.places});
});
}
constructor(props) {
super(props);
this.fetchPlaces = debounce(this.fetchPlaces, 200);
}```
I'd recommend you to go through React Hooks' official guide, by the end of the guide lies a full example of how to use react hooks.
You should use useState hook to manage states and use useEffect hook to load data from network.
const Foo = () =>{
// all hooks should be used in top level of the function component.
// orders matter.
// https://www.reactjs.org/docs/hooks-rules.html#only-call-hooks-at-the-top-level
const [q, setQ] = useState(''); // use hooks to declare q
const [places, setPlaces] = useState([]); // use hooks to declare places
// load data from network after React Nodes are rendered
useEffect(()=>{
get(`http://www.example.com/places/`, {
params: {q}
}).then(response => {
setPlaces(response.data.places); // call setPlaces to set state
});
}
,[1]); // passing a constant to the second Array parameter to strict the hook be called only for once, if left undefined, useEffect will be called after every render.
return // React Nodes
}
I've used react hooks for a while, you can checkout my full example here.
https://github.com/ShinChven/bootcamp/blob/master/console/src/pages/Admin/Users/Users.tsx
I do not see why you should call network with debounce, but here's a post for that.
https://www.freecodecamp.org/news/debounce-and-throttle-in-react-with-hooks/
const fetchPlaces = (q) => {
get(`http://www.example.com/places/`, {
params: {q}
}).then(response => {
setPlaces(response.data.places);
});
}
const deboucedFetchPlaces = debounce(fetchPlaces, 200)
Then in your code you can call deboucedFetchPlaces
You can do it like this.
const fetchMore = _.debounce(fetchPlaces, 500);
fetchPlaces(q) {
get(`http://www.example.com/places/`, {
params: {q}
}).then(response => {
this.setState({places: response.data.places});
});
}
fetchMore();
I'm trying to implement a custom hook to provide the app with a guest shopping cart. My hook wraps around the useMutation hook from Apollo and it saves the shopping cart id in a cookie while also providing a function to "reset" the cart (basically, to remove the cookie when the order is placed).
Code time! (some code omitted for brevity):
export const useGuestCart = () => {
let cartId;
const [createCart, { data, error, loading }] = useMutation(MUTATION_CREATE_CART);
console.log(`Hook!`);
if (!cartId || cartId.length === 0) {
createCart();
}
if (loading) {
console.log(`Still loading`);
}
if (data) {
console.log(`Got cart id ${data.createEmptyCart}`);
cartId = data.createEmptyCart;
}
const resetGuestCart = useCallback(() => {
// function body here
});
return [cartId, resetGuestCart];
};
In my component I just get the id of the cart using let [cartId, resetCart] = useGuestCart(); .
When I run my unit test (using the Apollo to provide a mock mutation) I see the hooked invoked several times, with an output that looks something like this:
console.log src/utils/hooks.js:53
Hook!
console.log src/utils/hooks.js:53
Hook!
console.log src/utils/hooks.js:59
Still loading
console.log src/utils/hooks.js:53
Hook!
console.log src/utils/hooks.js:62
Got cart id guest123
console.log src/utils/hooks.js:53
Hook!
console.log src/utils/hooks.js:53
Hook!
I'm only getting started with hooks, so I'm still having trouble grasping the way they work. Why so many invocations of the hook?
Thank you for your replies!
Think of hooks as having that same code directly in the component. This means that every time the component renders the hook will run.
For example you define:
let cartId;
// ...
if (!cartId || cartId.length === 0) {
createCart();
}
The content inside the statement will run on every render as cartId is created every time and it doesn't have any value assigned at that point. Instead of using if statements use useEffect:
export const useGuestCart = () => {
const [cartId, setCartId] = useState(0);
const [createCart, { data, error, loading }] = useMutation(
MUTATION_CREATE_CART
);
const resetGuestCart = () => {
// function body here
};
useEffect(() => {
if(!cartId || cartId.length === 0){
createCart();
}
}, [cartId]);
useEffect(() => {
// Here we need to consider the first render.
if (loading) {
console.log(`Started loading`);
} else {
console.log(`Finished loading`);
}
}, [loading]);
useEffect(() => {
// Here we need to consider the first render.
console.log(`Got cart id ${data.createEmptyCart}`);
setCartId(data.createEmptyCart);
}, [data]);
return [cartId, resetGuestCart];
};
Also notice that there is no actual benefit from using useCallback if the component which is receiving the function is not memoized.
I'm using React hooks both to fetch GraphQL data with react-apollo and to store local state:
const [userData, setUserData] = useState({})
const { loading, error, data } = useQuery(USER_QUERY)
However, I'm wondering how to store data to userData. Is this how it's supposed to work:
useEffect(() => {
setUserData(data)
}, [Object.entries(data).length])
Looks like what you have probably works. There is also a onCompleted option available in the options parameter. it takes a callback of type:
(data: TData | {}) => void
so this is another way of doing it:
const { loading, error, data } = useQuery(USER_QUERY, {onCompleted: setUserData})
What are you trying to do with the returned data that you are unable to accomplish by simply using it as destructured from the query hook? In most use cases it can be used immediately, as it will update itself when refetched.
If it is necessary (and it could be), as the other answer says, the useEffect hook you posted should work, but I would replace the dependency with simply data, to prevent an edge case where the response has an equal length consisting of different data and does not update:
useEffect(() => {
setUserData(data)
}, [data])
I think something like this would work - you will need to create the initial state with useState, could be empty array and then onComplete in the useQuery would setTranscationsData... it is triggered every render when state or props change. Could of course add an inital state inside useState which insn't an empty array.
const [transactionsData, setTransactionsData] = React.useState([]);
const { error, data } = useQuery(GET_TRANSACTIONS, {
onCompleted: () => {
setTransactionsData(data.transactions);
},
});
another example
const [getLegalStatement] = useLazyQuery(GET_LEGAL_STATEMENT, {
fetchPolicy: 'network-only',
onCompleted: (data) => {
setTempLegalStatement(data.getLegalStatement);
},
onError: () => {
setTempLegalStatement({
consentedLegalStatementHash: '',
consentedSuppliersHash: '',
statement: '',
suppliersModal: '',
});
setTimeout(() => {
setRefetchNeeded(true);
}, 10000);
},
});
Use onSuccess
const [userData, setUserData] = useState({})
const { data, isLoading, error } = useQuery('QueryKey', QueryFunction, { onSuccess: setUserData })
This onSuccess callback function will fire setUserData(data) for you automatically any time the query successfully fetches new data.
To elaborate above, you can't use onSuccess/onSettled because those will not rerun if the data is cached, so if you leave the component and come back before the query expires your data won't get set.
I'm building a fairly large SPA using Vue (and Laravel for RESTful API). I'm having a hard time finding resources about this online - what's a good practice to organise the code that communicates with the server?
Currently I have src/api.js file, which uses axios and defines some base methods as well as specific API endpoints (truncated):
import axios from 'axios';
axios.defaults.baseURL = process.env.API_URL;
const get = async (url, params = {}) => (await axios.get(url, { params }));
const post = async (url, data = {}) => (await axios.post(url, data));
export const login = (data) => post('users/login', data);
And then in my component, I can do
...
<script>
import { login } from '#/api';
...
methods: {
login() {
login({username: this.username, password: this.password})
.then() // set state
.catch() // show errors
}
}
</script>
Is this a good practice? Should I split up my endpoints into multiple files (e.g. auth, users, documents etc.)? Is there a better design for this sort of thing, especially when it comes to repetition (e.g. error handling, showing loading bars etc.)?
Thanks!
If you're just using Vue and expect to be fetching the same data from the same component every time, it's generally idiomatic to retrieve the data and assign it using the component's mounted lifecycle hook, like so:
<template>
<h1 v-if="name">Hello, {{name}}!</h1>
</template>
<script>
export default {
data() {
return {
name: '',
}
},
mounted() {
axios.get('https://example.com/api')
.then(res => {
this.name = res.data.name;
})
.catch(err =>
// handle error
);
},
};
</script>
If you're going to be using Vuex as mentioned in one of your comments, you'll want to put your API call into the store's actions property.
You'll end up with a Vuex store that looks something like this:
const store = new Vuex.Store({
state: {
exampleData: {},
},
mutations: {
setExampleData(state, data) {
state.exampleData = data;
},
},
actions: {
async getExampleData() {
commit(
'setExampleData',
await axios.get('https://www.example.com/api')
.then(res => res.data)
.catch(err => {
// handle error
});
);
},
}
});
Of course, breaking out your state, actions, and mutations into modules as your app grows is good practice, too!
If you use Vue CLI it will setup a basic project structure. With a HelloWorld component. You will want to break your vue app into components. Each component should have a defined role that ideally you could then unit test.
For example lets say you want to show list of products then you should create a product list component.
<Products :list="products" />
In your app you would do something like
data() {
return {
prodcuts: []
}
},
mounted() {
axios.get('/api/products').then(res => {
this.products = res.data
})
}
Whenever you see something that "is a block of something" make a component out of it, create props and methods and then on the mounted hook consume the api and populate the component.
How to write best way to fetch api resource in react app while we use redux in application.
my actions file is actions.js
export const getData = (endpoint) => (dispatch, getState) => {
return fetch('http://localhost:8000/api/getdata').then(
response => response.json()).then(
json =>
dispatch({
type: actionType.SAVE_ORDER,
endpoint,
response:json
}))
}
is it best way to fetch api?
The above code is fine.But there are few points you should look to.
If you want to show a Loader to user for API call then you might need some changes.
You can use async/await the syntax is much cleaner.
Also on API success/failure you might want to show some notification to user. Alternatively, You can check in componentWillReceiveProps to show notification but the drawback will be it will check on every props changes.So I mostly avoid it.
To cover this problems you can do:
import { createAction } from 'redux-actions';
const getDataRequest = createAction('GET_DATA_REQUEST');
const getDataFailed = createAction('GET_DATA_FAILURE');
const getDataSuccess = createAction('GET_DATA_SUCCESS');
export function getData(endpoint) {
return async (dispatch) => {
dispatch(getDataRequest());
const { error, response } = await fetch('http://localhost:8000/api/getdata');
if (response) {
dispatch(getDataSuccess(response.data));
//This is required only if you want to do something at component level
return true;
} else if (error) {
dispatch(getDataFailure(error));
//This is required only if you want to do something at component level
return false;
}
};
}
In your component:
this.props.getData(endpoint)
.then((apiStatus) => {
if (!apiStatus) {
// Show some notification or toast here
}
});
Your reducer will be like:
case 'GET_DATA_REQUEST': {
return {...state, status: 'fetching'}
}
case 'GET_DATA_SUCCESS': {
return {...state, status: 'success'}
}
case 'GET_DATA_FAILURE': {
return {...state, status: 'failure'}
}
Using middleware is the most sustainable way to do API calls in React + Redux applications. If you are using Observables, aka, Rxjs then look no further than redux-observable.
Otherwise, you can use redux-thunk or redux-saga.
If you are doing a quick prototype, then making a simple API call from the component using fetch is good enough. For each API call you will need three actions like:
LOAD_USER - action used set loading state before API call.
LOAD_USER_SUCC - when API call succeeds. Dispatch on from then block.
LOAD_USER_FAIL - when API call fails and you might want to set the value in redux store. Dispatch from catch block.
Example:
function mounted() {
store.dispatch(loadUsers());
getUsers()
.then((users) => store.dispatch(loadUsersSucc(users)))
.catch((err) => store.dispatch(loadUsersFail(err));
}