I am new to ReactJS and working with Hooks. I want to set state for object. Here is my code:
const StartPage = (props)=> {
const [user,setUser] = useState('')
const [password,setPassword] = useState('')
const [info,setInfo] = useState({
email:''
]})
const onUserChange=(e)=>{
const user = e.target.value
setUser(user)
}
const onPasswordChange=(e)=>{
const password = e.target.value
setPassword(password)
}
const onSubmit=(e)=>{
e.preventDefault()
const myHeader = new Headers ({
'APIKey':'*****',
"Content-Type": "application/json",
'Access-Control-Allow-Origin': '*',
'Access-Control-Expose-Headers':'headers'
})
fetch(`[my_link_to_api]?username=${user}&password=${password}`,{
method:'GET',
credentials: 'omit',
headers:myHeader,
})
.then(response =>response.json())
.then(data =>{
if(data!==undefined){
setInfo({...info, data})
}
console.log(info)
})
.then(()=>{
console.log(info)
history.push({
pathname:'/dashboard',
state:info
})
})
.catch((e)=>{
console.log(e)
})
}
return (
<div>
<form onSubmit={onSubmit}>
<input type="text" placeholder="username" onChange={onUserChange}></input>
<input type="password" placeholder="password" onChange={onPasswordChange}></input>
<button>Login</button>
</form>
</div>
)
}
The problem part is here:
I declare object initial state here:
const [info,setInfo] = useState({
email:''
})
And here:
.then(data =>{
if(data!==undefined){
setInfo({...info, data})
}
console.log(info)
})
it is just not working. It is not setting info and data in never written. How can I assign the received data (because I console logged it and it it received) to the info?
setInfo is asynchronous and you won't see the updated state until the next render, so when you do this:
if(data!==undefined){
setInfo({...info, data })
}
console.log(info)
you will see info before the state was updated.
You can use useEffect hook (which tells React that your component needs to do something after render) to see the new value of info:
const StartPage = props => {
const [user, setUser] = useState('');
...
useEffect(() => {
console.log(info);
}, [info]);
...
}
EDIT
Also as others have pointed out, you likely want to destructure data when setting the state: setInfo({...info, ...data }) (this entirely depends on how you are planning to use it), otherwise the state will look like this:
{
email: ...
data: ...
}
What is the structure of data received from the api call? you can try setting it like so -
setInfo({ ...info, email: data.email })
I'm not exactly sure what you mean by "not working" but it looks like you are deconstructing info but not data. My suspicion is that it is setting state but not the way you want. If data is an object with email as a property you most likely will want to deconstruct that too like this:
setInfo({...info, ...data})
You can use useEffect to console.log state changes if you want with something like this:
import React, { useState, useEffect } from 'react'
const StartPage = props => {
const [info,setInfo] = useState({ email:'' })
useEffect(() => {
console.log(info)
}, [info])
Related
I'm currently converting the logic in my mern (with typescript) project to use React/Tanstack query to learn this tool better.
I want to use useMutation to handle the post request logic from the details inputted in the form, in this login component but can't figure out how to do this. Any tips would be appreciated thanks. Below is the code from my login component
const Login = () => {
const navigate = useNavigate();
const [email, setEmail] = useState("");
const [password, setPassword] = useState("");
const [errorMsg, setErrorMsg] = useState("");
const [state, setState] = useContext(UserContext);
const handleSubmit = async (e: { preventDefault: () => void }) => {
e.preventDefault();
let response;
const { data: loginData } = await axios.post("http://localhost:5001/auth/login", {
email,
password,
});
response = loginData;
if (response.errors.length) {
return setErrorMsg(response.errors[0].msg);
}
setState({
data: {
id: response.data.user.id,
email: response.data.user.email,
stripeCustomerId: response.data.user.stripeCustomerId,
},
loading: false,
error: null,
});
localStorage.setItem("token", response.data.token);
axios.defaults.headers.common["authorization"] = `Bearer ${response.data.token}`;
navigate("/dashboard");
};
return (
<div className="login-card">
<div>
<h3>Login</h3>
</div>
<form onSubmit={handleSubmit}>
<div className="login-card-mb">
<label>Email</label>
<input type="email" value={email} onChange={(e) => setEmail(e.target.value)} />
</div>
<div className="login-card-mb">
<label>Password</label>
<input type="password" value={password} onChange={(e) => setPassword(e.target.value)} />
</div>
{errorMsg && <p>{errorMsg}</p>}
<button type="submit">Submit</button>
</form>
</div>
);
};
After setting up your project to use React Query ( Check the docs if you have not). You want to extract your api call to a separate function that takes an object. This object will hold the values you would like to post.
const Login = (dataToPost) => {
let res = await axios.post('url', dataToPost)
return res.data
}
Now that you have that, you can import useMutation from React Query. Once imported you can now use the hook. UseQuery, useMutation both contain a data variable so no need to create state for the data returned from your endpoint. In this example, I'm deconstructing the data and loading state. But most importantly the mutate function. Which allows you to fire off your api call. We add our api call to the hook. I'm renaming the mutate function to doLogin. It's a habit
const {data,isLoading,mutate:doLogin} = useMutation(Login)
Finally we can just call mutate(objectWithValues) wherever you want in your code. The data will initially be null and isLoading will be true once called. To tie it all together. Your handleSubmit could look as follows
const handleSubmit = () => {
e.preventDefault();
doLogin({email,password})
}
You also have the option of running functions on a success or error of the mutation
const {data,isLoading,mutate: doLogin} =
useMutation(Login, {
onError: (err) => console.log("The error",err),
onSuccess:(someStuff)=>console.log("The data being returned",someStuff)
})
I am creating a page for user to update personal data with React-Hook-Form.
Once paged is loaded, I use useEffect to fetch the user's current personal data and set them into default value of the form.
I put the fetched value into defaultValue of <Controller />.
However, it is just not showing in the text box.
Here is my code:
import React, {useState, useEffect, useCallback} from 'react';
import { useForm, Controller } from 'react-hook-form'
import { URL } from '../constants';
const UpdateUserData = props => {
const [userData, setUserData] = useState(null);
const { handleSubmit, control} = useForm({mode: 'onBlur'});
const fetchUserData = useCallback(async account => {
const userData = await fetch(`${URL}/user/${account}`)
.then(res=> res.json());
console.log(userData);
setUserData(userData);
}, []);
useEffect(() => {
const account = localStorage.getItem('account');
fetchUserData(account);
}, [fetchUserData])
const onSubmit = async (data) => {
// TODO
}
return (
<div>
<form onSubmit={handleSubmit(onSubmit)}>
<div>
<label>User Name:</label>
<Controller
as={<input type='text' />}
control={control}
defaultValue={userData ? userData.name : ''}
name='name'
/>
</div>
<div>
<label>Phone:</label>
<Controller
as={<input type='text' />}
control={control}
defaultValue={userData ? userData.phone : ''}
name='phone'
/>
</div>
<button>Submit</button>
</form>
</div>
);
}
export default UpdateUserData;
The called API is working well and the value is actually set to userData state.
{
name: "John",
phone: "02-98541566"
...
}
I also tried to setUserData with mock data in useEffect(), and it doesn't work either.
Is there any problem in my above code?
#tam answer is halfway through what is needed to make it work with version 6.8.3.
You need to provide the default value but also to useEffect to reset. That particular distinction is required if you have a form that you reload with another entity. I have a complete example in CodeSanbox here.
In a nutshell:
You need to define your defaultValues in the userForm.
const { register, reset, handleSubmit } = useForm({
defaultValues: useMemo(() => {
return props.user;
}, [props])
});
Then you need to listen to potential change.
useEffect(() => {
reset(props.user);
}, [props.user]);
The example in the Code Sandbox allows swapping between two users and have the form change its values.
You can use setValue (https://react-hook-form.com/api/useform/setvalue).
Import it from useForm:
const { handleSubmit, control, setValue} = useForm({ mode: 'onBlur' });
Then call it with the user data after it's received:
useEffect(() => {
if (userData) {
setValue([
{ name: userData.name },
{ phone: userData.phone }
]);
}
}, [userData]);
You can remove the default values from the form.
EDIT: See alternative answers below if this does not work.
setValue didn't work for me. Alternatively, you can use the reset method:
Reset either the entire form state or part of the form state.
Here is working code:
/* registered address */
const [registeredAddresses, setRegisteredAddresses] = useState([]);
const { register, errors, handleSubmit, reset } = useForm <FormProps> ({
validationSchema: LoginSchema,
});
/**
* get addresses data
*/
const getRegisteredAddresses = async () => {
try {
const addresses = await AddressService.getAllAddress();
setRegisteredAddresses(addresses);
setDataFetching(false);
} catch (error) {
setDataFetching(false);
}
};
useEffect(() => {
getRegisteredAddresses();
}, []);
useEffect(() => {
if (registeredAddresses) {
reset({
addressName: registeredAddresses[0].name,
tel: registeredAddresses[0].contactNumber
});
}
}, [registeredAddresses]);
Found another easy way, I used reset API from useForm
const { handleSubmit, register, reset } = useForm({ resolver });
After you call API and get back response data, you call reset with new apiData, make sure apiData key's are same as input keys (name attribute):
useEffect(() => {
reset(apiData);
}, [apiData]);
form's default values are cached and hence once you get the data from API, we reset the form state with new data.
#tommcandrew's setValue parameter formatting didn't work for me.
This format did:
useEffect(() => {
const object = localStorage.getItem('object');
setValue("name", object.name);
}, [])
although this post is 2 months old, I stumbled upon this issue today and searched for a couple of ways to do it. The most effective way I've come up with is using useMemo to set your defaultValues, like this :
const { control, errors, handleSubmit } = useForm({
reValidateMode: 'onChange',
defaultValues: useMemo(() => yourDefaultValues, [yourDefaultValues]),
});
This allows you to properly set values in your form, without the struggle of multiple implementations if you happen to have field arrays (which was my case).
This also works while using the advanced smart form component exemple from the official documentation. Let me know if you have any questions !
This works for nested objects (I'm using version 6.15.1)
useEffect(() => {
for (const [key, value] of Object.entries(data)) {
setValue(key, value, {
shouldValidate: true,
shouldDirty: true
})
}
}, [data])
Using reset is a simple solution.
const { reset } = useForm();
onClick={()=> reset({ firstname: 'Joe' }, { lastname: 'Doe' }) }
As of react-hook-form 7.41, you can use defaultValues with async functions like this:
const {
formState: { isLoading },
} = useForm({
defaultValues: fetch('API'),
// resetOptions: {
// keepDirtyValues: true
// }
});
now the defaultValue field type is look like this:
type AsyncDefaultValues<TFieldValues> = (payload?: unknown) => Promise<TFieldValues>;
isLoading for the async defaultValues loading state.
I am trying to update my 'state' array and insert items of type String into it with 'setState' but it doesn't works.
I know it's not work with push().
I also tried to update my 'state' array with the spread operator but it also doesn't work.
Here my code:
import React, { useState } from 'react';
import _, { debounce } from 'lodash';
export default function Search() {
const [state, setState] = useState([])
const handleChange = debounce(async (value) => {
const url = `http://localhost:3100/`
if (value == '') {
return
}
let response = await fetch(url, {
headers: {
'Content-Type': 'application/json'
},
method: 'POST',
body: JSON.stringify({ value })
})
let test = await response.json()
console.log(test)
setState(state.concat(test))
// setState([...state, test]) it also doesn't work
console.log(state)
}, 1000)
return (
<>
<div>
<input onChange={e => handleChange(e.target.value)} />
</div>
</>
)
}
The 'state' array remains empty. I need to understand why please.
1.) Change if(value == '') to if(value ==='')
2.) console.log(state) after your setState will return the previous value of state as the component has not refreshed yet. Look at the example here: https://codesandbox.io/s/friendly-ives-vvo13?file=/src/App.js:103-474 and type something and look at the console. Then type something else and look at the console. You will see the console is showing the state of what you previous typed. However, if you look at the {state} rendered inside of the return, it will show you the current state.
export default function App() {
const [state, setState] = useState([]);
const handleChange = debounce(async value => {
let test = ["cars", "boat", "bike"];
setState([...test, value]);
console.log(state);
}, 1000);
return (
<>
<div>
{state}
<input onChange={e => handleChange(e.target.value)} />
</div>
</>
);
}
So you are setting state, just accessing/reading it in the wrong place.
https://codesandbox.io/s/next-js-infinite-scroll-3vfem?file=/pages/Content.js
I added one line to this function from the demo above
const getMorePost = async () => {
const res = await fetch(
`https://jsonplaceholder.typicode.com/todos?_start=${posts.length}&_limit=20`
);
const newPosts = await res.json()
setHasMore(!!newPosts.length)
setPosts((post) => [...post, ...newPosts])
}
now scroll completes ok.
I am attempting to query my Firebase backend through a redux-thunk action, however, when I do so in my initial render using useEffect(), I end up with this error:
Error: Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate. React limits the number of nested updates to prevent infinite loops.
My action simply returns a Firebase query snapshot which I then received in my reducer. I use a hook to dispatch my action:
export const useAnswersState = () => {
return {
answers: useSelector(state => selectAnswers(state)),
isAnswersLoading: useSelector(state => selectAnswersLoading(state))
}
}
export const useAnswersDispatch = () => {
const dispatch = useDispatch()
return {
// getAnswersData is a redux-thunk action that returns a firebase snapshot
setAnswers: questionID => dispatch(getAnswersData(questionID))
}
}
and the following selectors to get the data I need from my snapshot and redux states:
export const selectAnswers = state => {
const { snapshot } = state.root.answers
if (snapshot === null) return []
let answers = []
snapshot.docs.map(doc => {
answers.push(doc.data())
})
return answers
}
export const selectAnswersLoading = state => {
return state.root.answers.queryLoading || state.root.answers.snapshot === null
}
In my actual component, I then attempt to first query my backend by dispatching my action, and then I try reading the resulting data once the data is loaded as follows:
const params = useParams() // params.id is just an ID string
const { setAnswers, isAnswersLoading } = useAnswersDispatch()
const { answers } = useAnswersState()
useEffect(() => {
setAnswers(params.id)
}, [])
if (!isAnswersLoading)) console.log(answers)
So to clarify, I am using my useAnswersDispatch to dispatch a redux-thunk action which returns a firebase data snapshot. I then use my useAnswersState hook to access the data once it is loaded. I am trying to dispatch my query in the useEffect of my actual view component, and then display the data using my state hook.
However, when I attempt to print the value of answers, I get the error from above. I would greatly appreciate any help and would be happy to provide any more information if that would help at all, however, I have tested my reducer and the action itself, both of which are working as expected so I believe the problem lies in the files described above.
Try refactoring your action creator so that dispatch is called within the effect. You need to make dispatch dependent on the effect firing.
See related
const setAnswers = (params.id) => {
const dispatch = useDispatch();
useEffect(() => {
dispatch(useAnswersDispatch(params.id));
}, [])
}
AssuminggetAnswersData is a selector, the effect will trigger dispatch to your application state, and when you get your response back, your selector getAnswersData selects the fields you want.
I'm not sure where params.id is coming from, but your component is dependent on it to determine an answer from the application state.
After you trigger your dispatch, only the application state is updated, but not the component state. Setting a variable with useDispatch, you have variable reference to the dispatch function of your redux store in the lifecycle of the component.
To answer your question, if you want it to handle multiple dispatches, add params.id and dispatch into the dependencies array in your effect.
// Handle null or undefined param.id
const answers = (param.id) => getAnswersData(param.id);
const dispatch = useDispatch();
useEffect(() => {
if(params.id)
dispatch(useAnswersDispatch(params.id));
}, [params.id, dispatch]);
console.log(answers);
As commented; I think your actual code that infinite loops has a dependency on setAnswers. In your question you forgot to add this dependency but code below shows how you can prevent setAnswers to change and cause an infinite loop:
const GOT_DATA = 'GOT_DATA';
const reducer = (state, action) => {
const { type, payload } = action;
console.log('in reducer', type, payload);
if (type === GOT_DATA) {
return { ...state, data: payload };
}
return state;
};
//I guess you imported this and this won't change so
// useCallback doesn't see it as a dependency
const getAnswersData = id => ({
type: GOT_DATA,
payload: id,
});
const useAnswersDispatch = dispatch => {
// const dispatch = useDispatch(); //react-redux useDispatch will never change
//never re create setAnswers because it causes the
// effect to run again since it is a dependency of your effect
const setAnswers = React.useCallback(
questionID => dispatch(getAnswersData(questionID)),
//your linter may complain because it doesn't know
// useDispatch always returns the same dispatch function
[dispatch]
);
return {
setAnswers,
};
};
const Data = ({ id }) => {
//fake redux
const [state, dispatch] = React.useReducer(reducer, {
data: [],
});
const { setAnswers } = useAnswersDispatch(dispatch);
React.useEffect(() => {
setAnswers(id);
}, [id, setAnswers]);
return <pre>{JSON.stringify(state.data)}</pre>;
};
const App = () => {
const [id, setId] = React.useState(88);
return (
<div>
<button onClick={() => setId(id => id + 1)}>
increase id
</button>
<Data id={id} />
</div>
);
};
ReactDOM.render(<App />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="root"></div>
Here is your original code causing infinite loop because setAnswers keeps changing.
const GOT_DATA = 'GOT_DATA';
const reducer = (state, action) => {
const { type, payload } = action;
console.log('in reducer', type, payload);
if (type === GOT_DATA) {
return { ...state, data: payload };
}
return state;
};
//I guess you imported this and this won't change so
// useCallback doesn't see it as a dependency
const getAnswersData = id => ({
type: GOT_DATA,
payload: id,
});
const useAnswersDispatch = dispatch => {
return {
//re creating setAnswers, calling this will cause
// state.data to be set causing Data to re render
// and because setAnser has changed it'll cause the
// effect to re run and setAnswers to be called ...
setAnswers: questionID =>
dispatch(getAnswersData(questionID)),
};
};
let timesRedered = 0;
const Data = ({ id }) => {
//fake redux
const [state, dispatch] = React.useReducer(reducer, {
data: [],
});
//securit to prevent infinite loop
timesRedered++;
if (timesRedered > 20) {
throw new Error('infinite loop');
}
const { setAnswers } = useAnswersDispatch(dispatch);
React.useEffect(() => {
setAnswers(id);
}, [id, setAnswers]);
return <pre>{JSON.stringify(state.data)}</pre>;
};
const App = () => {
const [id, setId] = React.useState(88);
return (
<div>
<button onClick={() => setId(id => id + 1)}>
increase id
</button>
<Data id={id} />
</div>
);
};
ReactDOM.render(<App />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="root"></div>
You just need to add params.id as a dependency.
Don't dispatch inside the function which you are calling inside useEffect but call another useEffect to dispatch
const [yourData, setyourData] = useState({});
useEffect(() => {
GetYourData();
}, []);
useEffect(() => {
if (yourData) {
//call dispatch action
dispatch(setDatatoRedux(yourData));
}
}, [yourData]);
const GetYourData= () => {
fetch('https://reactnative.dev/movies.json')
.then((response) => response.json())
.then((json) => {
if (result?.success == 1) {
setyourData(result);
}
})
.catch((error) => {
console.error(error);
});
};
I have created a custom Hook which fetches data from the server, sends dispatch to the store and returns data. It is usable if I want to list all comments in my app, however, I wanted to reuse it in the component where I need to fetch all comment replies, and that should happen only when certain button is clicked.
This is the hook down below.
import { useState, useEffect } from "react";
import { useDispatch, useSelector } from "react-redux";
const useFetch = (url, options, actionType, dataType) => {
const [response, setResponse] = useState([]);
const dispatch = useDispatch();
useEffect(() => {
(async () => {
const res = await fetch(url);
const json = await res.json();
setResponse(json);
})();
}, []);
useEffect(() => {
dispatch({ payload: response, type: actionType });
}, [response]);
const data = useSelector(state => state[dataType]);
return data;
};
export default useFetch;
Inside of my component I need to fetch replies when a button is clicked
const ParentComment = ({ comment }) => {
const handleShowMoreReplies = (e) => {
e.preventDefault();
}
let replies = useFetch(
`/api/comment_replies?comment_id=${comment.id}`,
null,
"REPLIES_RECEIVED",
"replies"
);
return (
<div>
<Comment comment={comment} />
<div className="replies">
{replies.map(reply => (
<Comment key={reply.id} comment={reply} />
))}
<a href="#" className="show_more" onClick={handleShowMoreReplies}>
Show More Replies ({comment.replies_count - 1})
</a>
</div>
</div>
);
};
If I put useFetch call inside of the handler I hget an error that Hooks can't be called there, but I need to call it only when the button is clicked so I don't know if there is a way to implement that.
I think you have subtle problems in your useFetch hook
1.your useEffect is having dep of ${url} and ${actionType } which you need to define.
2.In order to call this hook by clicking the button, you need to expose the setUrl as follows
const useFetch = ( initialUrl, options, actionType, dataType) => {
const [url, setUrl ] = useState(initialUrl);
const dispatch = useDispatch();
useEffect(() => {
const fetchData = async () => {
try {
const res = await fetch(url);
const data = await res.json();
dispatch({ payload: data, type: actionType });
} catch (error) {
console.log(error);
}
};
fetchData();
}, [url, actionType]);
const data = useSelector(state => state[dataType]);
return [ data, setUrl ];
};
export default useFetch;
Then when you are trying to use this hook, you can
const [data, fetchUrl] = useFetch(
`/api/comment_replies?comment_id=${comment.id}`,
null,
"REPLIES_RECEIVED",
"replies"
);
Then every time you have a button you can simply call
fetchUrl(${yourUrl}).
your hook will receive the new URL, which is the dep of your hook and rerender it.
Here is an related article
https://www.robinwieruch.de/react-hooks-fetch-data