Here is my setup:
const ParentComponent = ({ post_id }) => {
const { data: post } = useGetPost(post_id); // custom hook with useQuery under the hood
return (
<div>
{post.status === 'published' && (
<div className="margin-bottom">
<ChildComponent post_id={post_id} />
</div>
)}
</div>
);
};
const ChildComponent = ({ post_id }) => {
const { data: post } = useGetPost(post_id);
return <div>{post.title}</div>;
};
Whenever i change post status to 'published' – React Query spawns two getPost requests, first of which, for some reason, returns previous post status and second returns the right one. Problem is gone if i move post.status === 'published' check to ChildComponent, but it's not an option because of ChildComponent wrapper element ("margin-bottom") inside ParentComponent. Is there something i don't get?
UPDATE:
useGetPost hook:
export const useGetPost = (post_id) => {
return useQuery<IDiscussion, Error>(
['posts', post_id],
async () =>
await axios
.get(`/api/posts/${post_id}`)
.then((response) => response.data),
);
};
And my mutation function:
export const useUpdatePost = (post_id) => {
const queryClient = useQueryClient();
return useMutation(
async (data) => await axios.put(`/api/posts/${post_id}`, data),
{
onMutate: (data) => {
// updating react query cache before actual save
queryClient.setQueryData(['posts', post_id], (oldData) => ({
...oldData,
data,
}));
},
onSuccess: () => {
queryClient.refetchQueries(['posts', post_id]);
},
},
);
};
ChildComponent mounts after you manually set new query data in "onMutate". The query refetches on mount (default behavior), but mutation is not yet finished, so you see the old status. Then, on mutation success query refetches again and you see updated status.
That is why if your ChildComponent gets mounted unconditionally, you see only one request. You can just get rid of onMutate function and refetch the query only once, after mutation success.
How do I place this object inside an array: Dog API. Is an object inside another object. I'm trying to set setBreeds(breedsList.message) but does not work.
const basicUrl = `https://dog.ceo/api/breeds/`
const listUrl = `list/all`
const Home = () => {
// uses state to store the list of breeds
const [breeds, setBreeds] = useState([])
// fetch the list of breeds
const fetchBreeds = async () => {
let url
url = `${basicUrl}${listUrl}`
const response = await fetch(url)
const breedsList = await response.json()
setBreeds(breedsList)
}
// useeffect to mount the fetchBreeds function
useEffect(() => {
fetchBreeds()
}, [])
return (
<div>
{/* // maps */}
{breeds.map((breed) => console.log(breed))}
</div>
)
}
export default Home
You do like this
setBreeds(prevState => [...prevState, breedsList.message])
I'm not sure if that is what you are asking for but the following function turns the json response into a list of breed names. You could transform the object and then call setBreeds.
function transformToList(breedsResponse) {
const {message: breeds} = breedsResponse;
const breedMainNames = Object.keys(breeds);
return breedMainNames.reduce((acc, mainName) => {
const subNames = breeds[mainName];
if(subNames.length === 0) {
acc.push(mainName)
} else {
const combinedNames = subNames.map(name => `${name} ${mainName}`);
acc.push(...combinedNames);
}
return acc;
}, [])
};
I'm using react-router-dom v5, and react 16
Whenever I navigate like this:
from "/products/:someId" to "/products/:someOtherId"
the url changes but the components do not update accordingly
it's the same with queries.
"/products?search=something" or "/products?search=someOtherThing"
it does work when I'm in a different url, like "/" or "/users",
I'm using Link for navigation, I also tried the useHistory hook: history.push, history.replace and withRouter(myComponent);
This is how I'm getting data from queries/params
async function searchProducts(searchValue) {
const response = await axios.post(
"http://localhost:8000/api/products/search",
{ search: searchValue });
return response.data.body;
}
const useFetchData = (query) => {
const [products, setProducts] = useState([]);
useEffect(() => {
if (products.length === 0) {
// Use searchProducts for the request
searchProducts(query).then((foundProducts) => {
setProducts(foundProducts);
});
}
}, [products, query]);
return products;
};
then I useFetchData in my component which goes:
const ProductList = () => {
const history = useHistory();
// parsing query to be -> { search: "value" }
const urlQuery = queryString.parse(history.location.search);
const products = useFetchData(urlQuery.search);
const getList = () => {
return products.map((product) => {
return (
<li key={product._id}>
<ProductItem product={product} />
</li>
);
});
};
return <div className="container">{getList()}</div>;
};
The search button is in a different component for the header, it's always there since it's in the layout
<button className="header-search-button" onClick={handleClick}>
Search
</button>
and the handleClick:
// searchvalue has it's own onChange handler
const [searchValue, setSearchValue] = useState("");
// code...
const handleClick = () => {
// .... some code
// I also tried with push and Link
history.replace(`/products?search=${searchValue}`);
};
It's really difficult to tell without the code.
But my guess is you are able to change the /products?search=bag to /products?search=watch.
But after that it's not able to update the state and hence no re render.When you reload then the render happens.
It would be easier if we could see the code.
I have a User component and I want to make an api call to update the inactive state.
The problem that I´m having is that the useEffect is being called when the component receives props. That means it will make the call when component renders for the first time. What´s the pattern to avoid this and only make the call if inactive state changes?
My initial try was to remove user from the dependencies array. But I need to get the user.id to pass it to the service.
What´s the pattern to avoid making these unnecessary calls?
const User = (props) => {
const { user } = props
const [inactive, setInactive] = useState(user.inactive);
useEffect(() => {
const abortController = new AbortController();
const data = { inactive: Number(inactive) }
updateUserRecordInDatabase(user.id, data);
return () => {
abortController.abort();
};
}, [inactive, user])
return (
<button onClick={ () => setInactive(!inactive) } />toggle { user.name } state</button>
)
}
You can try:
const User = (props) => {
const { user } = props
const [inactive, setInactive] = useState(user.inactive);
const [numUpdate, setNumUpdate] = useState(0);
const {id} = user //You get id of use here
useEffect(() => {
if(numUpdate === 0){
// This is first time of useEffect
setNumUpdate(numUpdate + 1); // Only update when first time of useEffect
}
const abortController = new AbortController();
const data = { inactive: Number(inactive) }
updateUserRecordInDatabase(id, data);
return () => {
abortController.abort();
};
}, [inactive, id])
return (
<button onClick={ () => setInactive(!inactive) } />toggle { user.name } state</button>
)
}
How to send http request on button click with react hooks? Or, for that matter, how to do any side effect on button click?
What i see so far is to have something "indirect" like:
export default = () => {
const [sendRequest, setSendRequest] = useState(false);
useEffect(() => {
if(sendRequest){
//send the request
setSendRequest(false);
}
},
[sendRequest]);
return (
<input type="button" disabled={sendRequest} onClick={() => setSendRequest(true)}
);
}
Is that the proper way or is there some other pattern?
export default () => {
const [isSending, setIsSending] = useState(false)
const sendRequest = useCallback(async () => {
// don't send again while we are sending
if (isSending) return
// update state
setIsSending(true)
// send the actual request
await API.sendRequest()
// once the request is sent, update state again
setIsSending(false)
}, [isSending]) // update the callback if the state changes
return (
<input type="button" disabled={isSending} onClick={sendRequest} />
)
}
this is what it would boil down to when you want to send a request on click and disabling the button while it is sending
update:
#tkd_aj pointed out that this might give a warning: "Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in a useEffect cleanup function."
Effectively, what happens is that the request is still processing, while in the meantime your component unmounts. It then tries to setIsSending (a setState) on an unmounted component.
export default () => {
const [isSending, setIsSending] = useState(false)
const isMounted = useRef(true)
// set isMounted to false when we unmount the component
useEffect(() => {
return () => {
isMounted.current = false
}
}, [])
const sendRequest = useCallback(async () => {
// don't send again while we are sending
if (isSending) return
// update state
setIsSending(true)
// send the actual request
await API.sendRequest()
// once the request is sent, update state again
if (isMounted.current) // only update if we are still mounted
setIsSending(false)
}, [isSending]) // update the callback if the state changes
return (
<input type="button" disabled={isSending} onClick={sendRequest} />
)
}
You don't need an effect to send a request on button click, instead what you need is just a handler method which you can optimise using useCallback method
const App = (props) => {
//define you app state here
const fetchRequest = useCallback(() => {
// Api request here
}, [add dependent variables here]);
return (
<input type="button" disabled={sendRequest} onClick={fetchRequest}
);
}
Tracking request using variable with useEffect is not a correct pattern because you may set state to call api using useEffect, but an additional render due to some other change will cause the request to go in a loop
In functional programming, any async function should be considered as a side effect.
When dealing with side effects you need to separate the logic of starting the side effect and the logic of the result of that side effect (similar to redux saga).
Basically, the button responsibility is only triggering the side effect, and the side effect responsibility is to update the dom.
Also since react is dealing with components you need to make sure your component still mounted before any setState or after every await this depends on your own preferences.
to solve this issue we can create a custom hook useIsMounted this hook will make it easy for us to check if the component is still mounted
/**
* check if the component still mounted
*/
export const useIsMounted = () => {
const mountedRef = useRef(false);
const isMounted = useCallback(() => mountedRef.current, []);
useEffect(() => {
mountedRef.current = true;
return () => {
mountedRef.current = false;
};
});
return isMounted;
};
Then your code should look like this
export const MyComponent = ()=> {
const isMounted = useIsMounted();
const [isDoMyAsyncThing, setIsDoMyAsyncThing] = useState(false);
// do my async thing
const doMyAsyncThing = useCallback(async () => {
// do my stuff
},[])
/**
* do my async thing effect
*/
useEffect(() => {
if (isDoMyAsyncThing) {
const effect = async () => {
await doMyAsyncThing();
if (!isMounted()) return;
setIsDoMyAsyncThing(false);
};
effect();
}
}, [isDoMyAsyncThing, isMounted, doMyAsyncThing]);
return (
<div>
<button disabled={isDoMyAsyncThing} onClick={()=> setIsDoMyAsyncThing(true)}>
Do My Thing {isDoMyAsyncThing && "Loading..."}
</button>;
</div>
)
}
Note: It's always better to separate the logic of your side effect from the logic that triggers the effect (the useEffect)
UPDATE:
Instead of all the above complexity just use useAsync and useAsyncFn from the react-use library, It's much cleaner and straightforward.
Example:
import {useAsyncFn} from 'react-use';
const Demo = ({url}) => {
const [state, doFetch] = useAsyncFn(async () => {
const response = await fetch(url);
const result = await response.text();
return result
}, [url]);
return (
<div>
{state.loading
? <div>Loading...</div>
: state.error
? <div>Error: {state.error.message}</div>
: <div>Value: {state.value}</div>
}
<button onClick={() => doFetch()}>Start loading</button>
</div>
);
};
You can fetch data as an effect of some state changing like you have done in your question, but you can also get the data directly in the click handler like you are used to in a class component.
Example
const { useState } = React;
function getData() {
return new Promise(resolve => setTimeout(() => resolve(Math.random()), 1000))
}
function App() {
const [data, setData] = useState(0)
function onClick() {
getData().then(setData)
}
return (
<div>
<button onClick={onClick}>Get data</button>
<div>{data}</div>
</div>
);
}
ReactDOM.render(<App />, document.getElementById("root"));
<script src="https://unpkg.com/react#16/umd/react.development.js" crossorigin></script>
<script src="https://unpkg.com/react-dom#16/umd/react-dom.development.js" crossorigin></script>
<div id="root"></div>
You can define the boolean in the state as you did and once you trigger the request set it to true and when you receive the response set it back to false:
const [requestSent, setRequestSent] = useState(false);
const sendRequest = () => {
setRequestSent(true);
fetch().then(() => setRequestSent(false));
};
Working example
You can create a custom hook useApi and return a function execute which when called will invoke the api (typically through some onClick).
useApi hook:
export type ApiMethod = "GET" | "POST";
export type ApiState = "idle" | "loading" | "done";
const fetcher = async (
url: string,
method: ApiMethod,
payload?: string
): Promise<any> => {
const requestHeaders = new Headers();
requestHeaders.set("Content-Type", "application/json");
console.log("fetching data...");
const res = await fetch(url, {
body: payload ? JSON.stringify(payload) : undefined,
headers: requestHeaders,
method,
});
const resobj = await res.json();
return resobj;
};
export function useApi(
url: string,
method: ApiMethod,
payload?: any
): {
apiState: ApiState;
data: unknown;
execute: () => void;
} {
const [apiState, setApiState] = useState<ApiState>("idle");
const [data, setData] = useState<unknown>(null);
const [toCallApi, setApiExecution] = useState(false);
const execute = () => {
console.log("executing now");
setApiExecution(true);
};
const fetchApi = useCallback(() => {
console.log("fetchApi called");
fetcher(url, method, payload)
.then((res) => {
const data = res.data;
setData({ ...data });
return;
})
.catch((e: Error) => {
setData(null);
console.log(e.message);
})
.finally(() => {
setApiState("done");
});
}, [method, payload, url]);
// call api
useEffect(() => {
if (toCallApi && apiState === "idle") {
console.log("calling api");
setApiState("loading");
fetchApi();
}
}, [apiState, fetchApi, toCallApi]);
return {
apiState,
data,
execute,
};
}
using useApi in some component:
const SomeComponent = () =>{
const { apiState, data, execute } = useApi(
"api/url",
"POST",
{
foo: "bar",
}
);
}
if (apiState == "done") {
console.log("execution complete",data);
}
return (
<button
onClick={() => {
execute();
}}>
Click me
</button>
);
For this you can use callback hook in ReactJS and it is the best option for this purpose as useEffect is not a correct pattern because may be you set state to make an api call using useEffect, but an additional render due to some other change will cause the request to go in a loop.
<const Component= (props) => {
//define you app state here
const getRequest = useCallback(() => {
// Api request here
}, [dependency]);
return (
<input type="button" disabled={sendRequest} onClick={getRequest}
);
}
My answer is simple, while using the useState hook the javascript doesn't enable you to pass the value if you set the state as false. It accepts the value when it is set to true. So you have to define a function with if condition if you use false in the usestate