Develop Reference

How can i test custom fetch hook

I am struggling with an issue with the custom fetch hook.Simply i am trying to test my fetch hook if the data already fetched the hook needs to get data from cache instead of api.
The test case fails and looks like caching mechanism not working, but if i try on the browser with manual prop change caching mechanism works properly.
import { render, waitFor } from "#testing-library/react";
const renderList = (filterParams = testFilterParamsList[0]) =>
render(<List filterParams={filterParams} />);
it("should re-render without fetch", async () => {
const { rerender } = renderList(testFilterParamsList[0]);
rerender(<List filterParams={testFilterParamsList[1]} />);
expect(window.fetch).toHaveBeenCalledTimes(1);
});
// useFetch.js
import {useEffect, useReducer} from "react";
const cache = {};
const FETCH_REQUEST = "FETCH_REQUEST";
const FETCH_SUCCESS = "FETCH_SUCCESS";
const FETCH_ERROR = "FETCH_SUCCESS";
const INITIAL_STATE = {
isPending: false,
error: null,
data: [],
};
const useFetch = ({url, filterOptions}) => {
const [state, dispatch] = useReducer((state, action) => {
switch (action.type) {
case FETCH_REQUEST:return {...INITIAL_STATE, isPending: true};
case FETCH_SUCCESS: return {...INITIAL_STATE, isPending: false, data: action.payload};
case FETCH_ERROR: return {...INITIAL_STATE, isPending: false, error: action.payload};
default: return state;
}
}, INITIAL_STATE);
useEffect(() => {
const fetchData = async () => {
dispatch({type: FETCH_REQUEST});
if (cache[url]) {
const data = cache[url];
dispatch({type: FETCH_SUCCESS, payload: data});
} else {
try {
const response = await window.fetch(url);
let data = await response.json();
cache[url] = data
dispatch({type: FETCH_SUCCESS, payload: data});
} catch (err) {
dispatch({type: FETCH_ERROR, payload: err});
}
}
};
fetchData();
}, [filterOptions, url]);
return state;
};
export default useFetch;
// List.js
import useFetch from "../hooks/useFetch";
export const RocketsList = ({ filterParams }) => {
const { isPending, error, data } = useFetch({
url: "https://api.spacexdata.com/v3/launches/past",
name:filterParams.name,
});
return (
<div>
Doesn't matter
</div>
);
};

Can not navigate to another pages after login

i dont know where is the trouble. but when i tried to login, it dont wanna navigate into the next pages and stuck in modal login. please tell me whats wrong with my code?
let navigate = useNavigate();
const dispatch = useContext(UserContext);
const state = useContext(UserContext);
// console.log(state);
const [form, setForm] = useState({
email: "",
password: "",
});
const { email, password } = form;
const handleChange = (e) => {
setForm({
...form,
[e.target.name]: e.target.value,
});
};
const handleSubmitLog = async (e) => {
try {
e.preventDefault();
const config = {
headers: {
"Content-type": "application/json",
},
};
const body = JSON.stringify(form);
const response = await API.post("/login", body, config);
console.log(response.data);
if (response?.status == 200) {
dispatch({
type: "LOGIN_SUCCESS",
payload: response.data.data,
});
if (response.data.data.status == "admin") {
navigate('/admin')
} else {
navigate('/userid')
}
}
} catch (error) {
console.log(error);
}
}
here is the response in console, i dont know why this dispatch can not work well
{
"status": "Success",
"data": {
"users": {
"name": "mr.x",
"email": "mr.x#mail.com",
"token": "asfsa"
}
}
}
TypeError: dispatch is not a function
at handleSubmitLog (header.js:59:1)
and here is the body from userContext file. please check it and tell me if my code is wrong
export const UserContext = createContext();
const initialState = {
isLogin: false,
user: {},
};
const reducer = (state, action) => {
const { type, payload } = action;
switch (type) {
case "USER_SUCCESS":
case "LOGIN_SUCCESS":
localStorage.setItem("token", payload.token)
return {
isLogin: true,
user: payload,
};
case "AUTH_ERROR":
case "LOGOUT":
localStorage.removeItem("token")
return {
isLogin: false,
user: {},
};
default:
throw new Error();
}
};
export const UserContextProvider = ({ children }) => {
const [state, dispatch] = useReducer(reducer, initialState);
return (
<UserContext.Provider value={[state, dispatch]}>
{children}
</UserContext.Provider>
);
};

The UserContext value is an array [state, dispatch]:
<UserContext.Provider value={[state, dispatch]}>
{children}
</UserContext.Provider>
But the component is not correctly accessing the context value:
const dispatch = useContext(UserContext);
const state = useContext(UserContext);
Here both dispatch and state have are the same context value of [state, dispatch].
You need only one useContext(UserContext) access, either of the following:
Save the entire context value and use array indexing:
const userContext = useContext(UserContext);
...
// userContext[0]; state object/value
// userContext[1]; dispatch function
...
userContext[1]({
type: "LOGIN_SUCCESS",
payload: response.data.data,
});
Save the state and dispatch values directly using array destructuring assignment:
const [state, dispatch] = useContext(UserContext);
...
dispatch({
type: "LOGIN_SUCCESS",
payload: response.data.data,
});

Try this:
const { state, dispatch } = useContext(AppContext)

Why is the array in my redux reducer not available from another component after a redirect to another page of my app?

I have two separate components. I want to have a button that when clicked on will add an element to an array in my reducer and redirect to another component, this component that gets redirected to needs to render the data that was just added to the array. The page redirects to the component I want but the data does not load and the console.logs don't show anything.
This is the component that has the redirect button. On this component the console.log(socialNetworkContract.members[0]) shows the string I expect.
const Posts = () => {
const dispatch = useDispatch();
const getProfile = async (member) => {
const addr = await dispatch({ type: 'ADD_MEMBER', response: member })
console.log(member)
window.location.href='/member'
console.log('----------- member------------')
console.log(socialNetworkContract.members[0])
}
const socialNetworkContract = useSelector((state) => state.socialNetworkContract)
return (
<div>
{socialNetworkContract.posts.map((p, index) => {
return <tr key={index}>
<button onClick={() => getProfile(p.publisher)}>Profile</button>
</tr>})}
</div>
)
}
export default Posts;
This is my reducer
import { connect, useDispatch, useSelector } from "react-redux";
let init = {
posts:[],
post:{},
profiles:[],
profile:{},
members:[],
member:{}
}
export const socialNetworkContract = (state = init, action) => {
const { type, response } = action;
switch (type) {
case 'ADD_POST':
return {
...state,
posts: [...state.posts, response]
}
case 'SET_POST':
return {
...state,
post: response
}
case 'ADD_PROFILE':
return {
...state,
profiles: [...state.profiles, response]
}
case 'SET_PROFILE':
return {
...state,
profile: response
}
case 'ADD_MEMBER':
return {
...state,
members: [...state.members, response]
}
case 'SET_MEMBER':
return {
...state,
member: response
}
default: return state
}
};
and this is the component that is redirected to. this just says undefined in console.log(socialNetworkContract.members[0])
const Member = () => {
const [user, setUser] = useState({});
const socialNetworkContract = useSelector((state) => state.socialNetworkContract)
useEffect(async()=>{
try {
const pro = socialNetworkContract.members[0]
console.log(socialNetworkContract.members[0])
await setUser(pro)
console.log(socialNetworkContract.members[0])
} catch (e) {
console.error(e)
}
}, [])
I have the route set in Routes.js as
<Route path="/member" exact component={Member} />

Use history.push('/') instead of window.location.href which will reload your whole page and you will lost your local state data.
const {withRouter} from "react-router-dom";
const Posts = (props) => {
const dispatch = useDispatch();
const getProfile = async (member) => {
const addr = await dispatch({ type: 'ADD_MEMBER', response: member })
console.log(member)
props.history.push('/member');
console.log('----------- member------------')
console.log(socialNetworkContract.members[0])
}
const socialNetworkContract = useSelector((state) => state.socialNetworkContract)
return (
<div>
{socialNetworkContract.posts.map((p, index) => {
return <tr key={index}>
<button onClick={() => getProfile(p.publisher)}>Profile</button>
</tr>})}
</div>
)
}
export default withRouter( Posts );

useState won't update the state when I set it in react

I need to render a component that has a route using react router. the first component has a button that when clicked needs to render another component that has state passed in from the first component. The page redirects but doesn't load. All of the data from the first component I want is passed in but it wont set state when I use setProfile(p). All the other console.log()s in the member component show all the data I expect but it won't set the state with this data.
import {useLocation} from "react-router-dom";
const Member = (props)=> {
const [user, setUser] = useState({});
const [profile, setProfile] = useState({});
const [user, setUser] = useState({});
const { state } = useLocation();
const [profile, setProfile] = useState({});
const dispatch = useDispatch();
const [list, setList] = useState([]);
const [posts, setPosts] = useState([]);
const [snInstance, setsnInstance] = useState({});
// run effect when user state updates
useEffect(() => {
const doEffects = async () => {
try {
// const p = await incidentsInstance.usersProfile(state.user, { from: accounts[0] });
// const a = await snInstance.getUsersPosts(state.user, { from: accounts[0] });
if (state && state.user) {
setUser(state.user);
}
const accounts = await MyWeb3.getInstance().getAccounts();
setAccounts(accounts);
console.log(accounts)
const incidents = MyWeb3.getInstance().getContract(Incidents)
const incidentsInstance = await MyWeb3.getInstance().deployContract(incidents);
const sn = MyWeb3.getInstance().getContract(SocialNet)
const snInstance = await MyWeb3.getInstance().deployContract(sn);
setsnInstance(snInstance);
const pro = socialNetworkContract.members[0]
console.log(pro)
const p = await incidentsInstance.usersProfile(pro, { from: accounts[0] });
const a = await snInstance.getUsersPosts(pro, { from: accounts[0] });
console.log(a)
console.log(p)
setProfile(p)
} catch (e) {
console.error(e)
}
}
doEffects();
}, [profile, state]);
const socialNetworkContract = useSelector((state) => state.socialNetworkContract)
return (
<div class="container">
<a target="_blank">Name : {profile.name}</a>
{socialNetworkContract.posts.map((p, index) => {
return <tr key={index}>
{p.message}
</tr>})}
</div>
)
}
export default Member;
This is the parent component I want to redirect from
const getProfile = async (member) => {
const addr = dispatch({ type: 'ADD_MEMBER', response: member })
console.log(member)
}
const socialNetworkContract = useSelector((state) => state.socialNetworkContract)
return (
<div>
{socialNetworkContract.posts.map((p, index) => {
return <tr key={index}>
<button onClick={() => getProfile(p.publisher)}>Profile</button>
</tr>})}
</div>
)
}
export default withRouter(Posts);
I have this component working when I don't have a dynamic route that needs data passing in from the parent component It's redirecting from.
My routes.js looks like
const Routes = (props) => {
return (
<Switch>
<Route path="/member" exact component={Member} />
<Route path="/posts" exact component={Posts} />
<Redirect exact to="/" />
</Switch>
)
}
export default Routes
This is the reducer
import { connect, useDispatch, useSelector } from "react-redux";
let init = {
posts:[],
post:{},
profiles:[],
profile:{},
members:[],
member:{}
}
export const socialNetworkContract = (state = init, action) => {
const { type, response } = action;
switch (type) {
case 'ADD_POST':
return {
...state,
posts: [...state.posts, response]
}
case 'SET_POST':
return {
...state,
post: response
}
case 'ADD_PROFILE':
return {
...state,
profiles: [...state.profiles, response]
}
case 'SET_PROFILE':
return {
...state,
profile: response
}
case 'ADD_MEMBER':
return {
...state,
members: [...state.members, response]
}
case 'SET_MEMBER':
return {
...state,
member: response
}
default: return state
}
};

It doesn't make any sense that you would dispatch({ type: 'ADD_MEMBER', response: member }) with a member object that came from the publisher property of a post. That info is already in your state. You probably need to be normalizing your state better so that you can select it where you need it.
You want to use the Link component from react-router-dom to navigate to a member's profile page. Your Route should render the correct profile based on an id or username property in the URL. Don't pass through the data when you redirect, just go to the correct URL. On that Member page you can get the user from the state by looking up the id.
In Posts:
<Link to={`/member/${p.publisher.id}`}><button>Profile</button></Link>
In Routes:
<Route path="/member/:id" component={Member} />
In Member:
const Member = () => {
const { id } = useParams();
const profile = useSelector((state) =>
state.socialNetworkContract.members.find((user) => user.id === id)
);
const dispatch = useDispatch();
useEffect(() => {
const doEffects = async () => {
if ( ! profile ) {
dispatch(loadUser(id));
}
};
doEffects();
}, [dispatch, profile, id]);

Why is State Undefined? [Hooks/Redux]

I'm trying to use Redux via hooks but the state keeps coming back with an empty array rather than the data from the fetch request.
Actions
export const loading = payload => {
return {
type: types.LOADING,
payload
}
}
export const getBudget = payload => {
return {
type: types.BUDGET_DATA,
payload
}
}
export const budgetData = () => {
return dispatch => {
dispatch(loading(true))
const url = `${URL_BUDGET}`
fetch(url)
.then(response => dispatch(getBudget(response.data)))
.catch(err => console.log(err))
dispatch(loading(false))
}
}
Reducer
import * as types from '../types'
const initialState = {
budget: []
}
export default (state = initialState, action) => {
switch (action.types) {
case types.BUDGET_DATA:
return {
...state,
budget: action.payload
}
default:
return state
}
}
Component
const Home = () => {
useDispatch(budgetData(), categoryData())
const state = useSelector(state => state.data)
const budgets = useSelector(state => state.data.budget)
const categories = useSelector(state => state.data.category)
//console.log(this.props.dataReducer)
return (
<div>
content
</div>
)
}
export default Home
I can't seem to understand why the fetch request isn't fulfilled.
My API has the following format of data...
{"meta":{},"data":{"example":[{"timestamp":28378545,"value":5}],...}}
Is there an issue with dispatching?! Adding loading hasn't helped either!

useDispatch returns a dispatch function that subsequently needs to be called. If you want to do this just one time when the component is first rendered, you can pair it with a useEffect that has no dependencies:
const Home = () => {
const dispatch = useDispatch()
const budgets = useSelector(state => state.data.budget)
const categories = useSelector(state => state.data.category)
useEffect(() => {
dispatch(budgetData())
dispatch(categoryData())
}, [])
return (
<div>
content
</div>
)
}
export default Home