I'm trying to learn redux-observables but I seem to be having an issue getting my app to return data. I keep getting the error below and I'm not sure where I'm going wrong or what the error actually means.
I'm trying to learn redux-observables but I seem to be having an issue getting my app to return data. I keep getting the error below and I'm not sure where I'm going wrong or what the error actually means.
I'm trying to learn redux-observables but I seem to be having an issue getting my app to return data. I keep getting the error below and I'm not sure where I'm going wrong or what the error actually means.
I'm trying to learn redux-observables but I seem to be having an issue getting my app to return data. I keep getting the error below and I'm not sure where I'm going wrong or what the error actually means.
ERR: fetchData is not a function
I need help
Contsants
export const FETCH_DATA = "FETCH_DATA";
export const FETCH_DATA_FAIL = "FETCH_DATA_FAIL ";
Action
import { FETCH_DATA, FETCH_DATA_FAIL } from "../contsants/contsants";
export const fetchData = (exampleData = {}) => ({
type: FETCH_DATA,
payload: exampleData
});
export const fetchDataFail = () => ({
type: FETCH_DATA_FAIL
});
Store
import { createStore } from "redux";
import rootReducer from "../Reducer/reducer";
const store = createStore(rootReducer);
export default store;
Reducer
import { FETCH_DATA, FETCH_DATA_FAIL } from "../contsants/contsants";
import { combineReducers } from "redux";
const initialState = {};
export const exampleData = (state = initialState, action: any) => {
switch (action.type) {
case FETCH_DATA:
return action.payload;
case FETCH_DATA_FAIL:
return {};
default:
return state;
}
};
export default combineReducers({
exampleData
});
Epics
import "rxjs";
import axios from "axios";
import { from, of } from "rxjs";
import { mergeMap, map, catchError } from "rxjs/operators";
import { ofType } from "redux-observable";
import { FETCH_DATA } from "../contsants/contsants";
import { fetchData, fetchDataFail } from "../Actions/action"
export const exampleEpic = (action$: any) =>
action$.pipe(
ofType(FETCH_DATA),
mergeMap((action) =>
from(axios.get("jsonplaceholder.typicode.com/todos/1")).pipe(
map((response) => fetchData(response.data)),
catchError(() => of(fetchDataFail()))
)
)
);
App
import { fetchData } from './Actions/action'
import { connect } from "react-redux";
function App(data: any, fetchData: any) {
const handleClickShowsTodos = () => {
fetchData()
console.log(data);
}
return (
<div>
<input type="text" />
<button onClick={handleClickShowsTodos}>ShowsTodo</button>
</div>
);
}
const mapStateToProps = (state: any) => {
return {
data: state
};
};
function mapDispatchToProps(dispatch: any) {
return {
fetchData: () => {
console.log('dispatch')
dispatch(fetchData())
}
};
}
export default connect(mapStateToProps, mapDispatchToProps)(App);
Related
I was trying to run my Redux app with redux-saga.
Basically on my store.js I have the following codes:
import { applyMiddleware, createStore } from "redux";
import createSagaMiddleware from "redux-saga";
import logger from "redux-logger";
import rootReducer from "./reducers/rootReducer";
import rootSaga from "./sagas/userSagas";
const sagaMiddleware = createSagaMiddleware();
const middleware = [sagaMiddleware];
if (process.env_NODE_ENV === "development") {
middleware.push(logger);
}
const store = createStore(rootReducer, applyMiddleware(...middleware));
sagaMiddleware.run(rootSaga);
export default store;
My usersApi.js looks something like this:
import axios from "axios";
export const loadUsersApi = async () => {
await axios.get("http://localhost:5000/users");
};
And here is my userSagas:
import * as type from "../actionType";
import {
take,
takeEvery,
takeLatest,
put,
all,
delay,
fork,
call,
} from "redux-saga/effects";
import { loadUsersSuccess, loadUsersError } from "../actions/userAction";
import { loadUsersApi } from "../services/userApi";
export function* onLoadUsersStartAsync() {
try {
const response = yield call(loadUsersApi);
if (response.status === 200) {
yield delay(500);
yield put(loadUsersSuccess(response.data));
}
} catch (error) {
yield put(loadUsersError(error.response.data));
}
}
export function* onLoadUsers() {
yield takeEvery(type.LOAD_USERS_START, onLoadUsersStartAsync);
}
const userSagas = [fork(onLoadUsers)];
export default function* rootSaga() {
yield all([...userSagas]);
}
When I run this on my HomePage.js file where I load and dispatch the data:
import React, { useEffect } from "react";
import { useDispatch, useSelector } from "react-redux";
import { loadUsersStart } from "../redux/actions/userAction";
export default function HomePage() {
const dispatch = useDispatch();
useEffect(() => {
dispatch(loadUsersStart());
}, [dispatch]);
return (
<div>
<h1>Home</h1>
</div>
);
}
It gave me this error:
[HMR] Waiting for update signal from WDS...
index.js:1 TypeError: Cannot read properties of undefined (reading 'data')
at onLoadUsersStartAsync (userSagas.js:25)
at onLoadUsersStartAsync.next (<anonymous>)
at next (redux-saga-core.esm.js:1157)
at currCb (redux-saga-core.esm.js:1251)
index.js:1 The above error occurred in task onLoadUsersStartAsync
created by takeEvery(LOAD_USERS_START, onLoadUsersStartAsync)
created by onLoadUsers
created by rootSaga
Tasks cancelled due to error:
takeEvery(LOAD_USERS_START, onLoadUsersStartAsync)
I am not sure what's causing this error, but even the logger of my app doesn't even show the actions being dispatched.
Any idea how can I fix this issue?
You need to return promise from
export const loadUsersApi = () => {
return axios.get("http://localhost:5000/users");
};
Maybe next time try to use typescript. It will prevent You from similar mistakes
Alternatively, you can build your redux without using redux-saga.
This is how I usually set them up:-
A. Reducer
/slices/auth.js
import { createSlice } from '#reduxjs/toolkit'
const initialState = {
users: [],
loading: false,
success: false,
error: false,
message: ''
}
export const usersSlice = createSlice({
name: 'users',
initialState,
// // The `reducers` field lets us define reducers and generate associated actions
reducers: {
setUsers: (state, action) => {
// Redux Toolkit allows us to write "mutating" logic in reducers. It
// doesn't actually mutate the state because it uses the Immer library,
// which detects changes to a "draft state" and produces a brand new
// immutable state based off those changes
state.users = action.payload
},
setLoading: (state, action) => {
state.loading = action.payload
},
setSuccess: (state, action) => {
state.success = action.payload.status
state.message = action.payload.message
},
setError: (state, action) => {
state.error = action.payload.status
state.message = action.payload.message
}
}
})
export const { setUsers, setLoading, setSuccess, setError, setMessage } = usersSlice.actions;
// The function below is called a selector and allows us to select a value from
// the state. Selectors can also be defined inline where they're used instead of
// in the slice file. For example: `useSelector((state: RootState) => state.counter.value)`
export const selectUsers = (state) => state.users.users
export const selectLoading = (state) => state.users.loading
export const selectSuccess = (state) => state.users.success
export const selectError = (state) => state.users.error
export const selectMessage = (state) => state.users.message
export default usersSlice.reducer;
B. Store
store.js
import { configureStore, getDefaultMiddleware } from '#reduxjs/toolkit'
import usersReducer from '../slices/users'
export const store = configureStore({
reducer: {
users: usersReducer
},
middleware: getDefaultMiddleware({
serializableCheck: false
})
})
C. App Component
import { Provider } from 'react-redux'
import { store } from '../app/store'
export default function App() {
return {
<>
<Provider store={store}>
{/* your content... */}
</Provider>
</>
}
}
D. Component (where you use the redux)
import { useContext, useEffect } from 'react'
import { useDispatch, useSelector } from 'react-redux'
import { selectUsers, selectLoading, selectSuccess, selectError, selectMessage, setUsers, setLoading, setSuccess, setError } from '../slices/users'
import axios from 'axios'
export default function HomePage() {
const dispatch = useDispatch()
const users = useSelector(selectUser)
const loading = useSelector(selectLoading)
const success = useSelector(selectSuccess)
const error = useSelector(selectorError)
const message = useSelector(selectorMessage)
useEffect(() => {
async function init() {
dispatch(setLoading(true))
const response = await axios.get('http://localhost:5000/users')
if(response?.status == 200) {
dispatch(setUsers(response?.data?.data))
dispatch(setSuccess({ status: true, message: 'Successfully get users data.' }))
} else {
dispatch(setError({ status: true, message: 'Failed to get data.' }))
}
dispatch(setLoading(false))
}
return init()
}, [])
return {
<>
{user}
</>
}
}
I'm new to React, Redux and have been following tutorials on the topic. I'm come across a lot of issues that I've been able to resolve but I've come across an issue I can't resolve. I set up store, and can even view it through Chrome's Redux Tools and it show correctly, however when I try and dispatch to the Store, I always get a Cannot read property 'dispatch' of undefined error. I have followed numerous tutorials letter for letter, and am still stuck with the same error message.
Index.Js
import Layout from '../components/layout/Layout';
import Home from '../components/Home';
import { getRooms } from '../redux/actions/roomActions';
import { wrapper } from '../redux/store';
export default function Index() {
return (
<Layout>
<Home />
</Layout>
);
}
export const getServerSideProps = wrapper.getServerSideProps(
async ({ req, store }) => {
await store.dispatch(getRooms(req));
}
);
roomConstants.js
export const ALL_ROOMS_SUCCESS = 'ALL_ROOMS_SUCCESS';
export const ALL_ROOMS_FAIL = 'ALL_ROOMS_FAIL';
export const CLEAR_ERRORS = 'CLEAR_ERRORS';
reducer.js
import { combineReducers } from 'redux';
import { allRoomsReducer } from './roomReducers';
const reducer = combineReducers({
allRooms: allRoomsReducer,
});
export default reducer;
Store.js
import { createStore, applyMiddleware } from 'redux';
import { HYDRATE, createWrapper } from 'next-redux-wrapper';
import thunkMiddleware from 'redux-thunk';
import reducers from './reducers/reducers';
const bindMiddleware = (middleware) => {
if (process.env.NODE_ENV !== 'production') {
const { composeWithDevTools } = require('redux-devtools-extension');
return composeWithDevTools(applyMiddleware(...middleware));
}
return applyMiddleware(...middleware);
};
const reducer = (state, action) => {
if (action.type === HYDRATE) {
const nextState = {
...state,
...action.payload,
};
return nextState;
} else {
return reducers(state, action);
}
};
const initStore = () => {
return createStore(reducer, bindMiddleware([thunkMiddleware]));
};
export const wrapper = createWrapper(initStore);
roomReducer.js
import {
ALL_ROOMS_SUCCESS,
ALL_ROOMS_FAIL,
CLEAR_ERRORS,
} from '../constants/roomConstants';
// All rooms reducer
export const allRoomsReducer = (state = { rooms: [] }, action) => {
switch (action.type) {
case ALL_ROOMS_SUCCESS:
return {
roomsCount: action.payload.roomsCount,
resPerPage: action.payload.resPerPage,
filteredRoomsCount: action.payload.filteredRoomsCount,
rooms: action.payload.rooms,
};
case ALL_ROOMS_FAIL:
return {
error: action.payload,
};
case CLEAR_ERRORS:
return {
...state,
error: null,
};
default:
return state;
}
};
roomAcion.js
import axios from 'axios';
import absoluteUrl from 'next-absolute-url';
import {
ALL_ROOMS_SUCCESS,
ALL_ROOMS_FAIL,
CLEAR_ERRORS,
} from '../constants/roomConstants';
//Clear errors
export const clearErrors = () => async (dispatch) => {
return dispatch({
type: CLEAR_ERRORS,
});
};
// Get all rooms
export const getRooms = (req) => async (dispatch) => {
try {
const { origin } = absoluteUrl(req);
const { data } = await axios.get(`${origin}/api/rooms`);
dispatch({
type: ALL_ROOMS_SUCCESS,
payload: data,
});
} catch (error) {
dispatch({
type: ALL_ROOMS_FAIL,
payload: error.response.data.message,
});
}
};
in index.js, your getServerSideProps function should read this;
export const getServerSideProps = wrapper.getServerSideProps((store) => async ({ req }) => {
await store.dispatch(getRooms(req));})
Use the old version of next-redux-wrapper like 6.0.2
I have an app with 2 reducers (city and doctor)
I use sagas.
I have a problem that with weird state overrides.
For example here is the start of fetch doctors action. As you see state was changed for doctor isLoading: false to isLoading: true
After that fetch cities action was started right before. And isLoading for doctors was changed back to false.
On every action dispatch, another reducer state reset.
I have doubt that it's a NextJS specific problem so root store is creating couple of times and cause a race condition.
Technologies: react, redux, react-redux, next-redux-wrapper, next-redux-saga, redux-saga
app.js
....
export default withRedux(createStore)(withReduxSaga(MyApp))
store.js
import { applyMiddleware, createStore } from 'redux'
import createSagaMiddleware from 'redux-saga'
import rootReducer from './rootReducer'
import rootSaga from './rootSaga'
const bindMiddleware = middleware => {
if (process.env.NODE_ENV !== 'production') {
const { composeWithDevTools } = require('redux-devtools-extension')
return composeWithDevTools(applyMiddleware(...middleware))
}
return applyMiddleware(...middleware)
}
function configureStore(initial={}) {
const sagaMiddleware = createSagaMiddleware()
const store = createStore(
rootReducer,
initial,
bindMiddleware([sagaMiddleware])
)
store.sagaTask = sagaMiddleware.run(rootSaga)
return store
}
export default configureStore
rootReducer.js
import { combineReducers } from 'redux'
import { cityReducer } from "./reducers/city"
import { doctorReducer } from "./reducers/doctor"
export default combineReducers({
city: cityReducer,
doctor: doctorReducer
})
city/reducer.js
import {actionTypes} from "../../actions/city"
const initialState = {
cities: []
}
export const cityReducer = (state = initialState, action) => {
switch (action.type) {
case actionTypes.FETCH_CITIES:
return initialState
case actionTypes.FETCH_CITIES_SUCCESS:
return {
cities: action.data
}
case actionTypes.FETCH_CITIES_FAILURE:
return initialState
default:
return initialState
}
}
city/actions.js
export const actionTypes = {
FETCH_CITIES: 'FETCH_CITIES',
FETCH_CITIES_SUCCESS: 'FETCH_CITIES_SUCCESS',
FETCH_CITIES_FAILURE: 'FETCH_CITIES_FAILURE',
}
export const fetchCities = () => {
return {
type: actionTypes.FETCH_CITIES
}
}
export const fetchCitiesSuccess = (data) => {
return {
type: actionTypes.FETCH_CITIES_SUCCESS,
data
}
}
export const fetchCitiesFailure = () => {
return {
type: actionTypes.FETCH_CITIES_FAILURE
}
}
city/saga.js
import {call, put, takeLatest} from "redux-saga/effects"
import {actionTypes, fetchCitiesFailure, fetchCitiesSuccess} from "../../actions/city"
import {getCities} from "../../api"
export function* watchFetchCitiesRequest() {
yield takeLatest(actionTypes.FETCH_CITIES, workerFetchCitiesRequest)
}
function* workerFetchCitiesRequest() {
try {
const {data} = yield call(getCities)
yield put(fetchCitiesSuccess(data.results))
} catch (e) {
yield put(fetchCitiesFailure())
}
}
(!) For the doctors reducer/saga/actions the structure is the same except names.
Page.js is the main layout for every page. Basically wraps every page content in _document.js
const Page = ({dispatch}) => {
useEffect(() => {
dispatch(fetchCities())
}, [])
}
const mapStateToProps = ({city}) => ({cities: city.cities})
export default connect(mapStateToProps)(Page)
DoctorList.js Component that /doctor page consumes
import {useEffect} from "react"
import {fetchDoctors} from "../../actions/doctor"
import {getCity} from "../../utils/functions"
import {DoctorItemPreview} from "./DoctorItem"
const DoctorList = ({dispatch, isLoading, isError, response}) => {
useEffect(() => {
getCity() ? dispatch(fetchDoctors()) : null
},[getCity()])
return <>
{!isLoading ? <>
</> : <>
{[...Array(10)].map((e, i) => <span key={i}>
<DoctorItemPreview/>
</span>)}
</>}
</>
}
const mapStateToProps = ({doctor, city}) => ({
isLoading: doctor.isLoading,
isError: doctor.isError,
response: doctor.response,
})
export default connect(mapStateToProps)(DoctorList)
What can be the place where the problem appears? What parts of code do you need for the answer? Thanks
I am pretty sure your reducers will overwrite your current state when returning initialState. See this answer on GitHub.
There are no known race conditions or other problems related to multiple root stores nor reducers in next-redux-saga.
I'm new to React/Redux. I'm making an app using an API but the code doesn't work. When I run the code it says "this.props.recipes.map is not a function" and doesn't render anything.
If I change payload to: "payload: response.data.recipes" then the error changes to "Given action "FETCH_RECIPE", reducer "recipes" returned undefined." but no errors on screen (only in console). I thought writing "(state = [], action)" would solve the problem but it seems not. What's the problem and how do I fix this error?
Action Creator
import recipe from '../apis/recipe';
export const fetchRecipe = () => async dispatch => {
const response = await recipe.get('');
dispatch({ type: 'FETCH_RECIPE', payload: response.data })
};
Reducer
import { combineReducers } from 'redux';
const recipeReducer = (state = [], action) => {
switch(action.type) {
case 'FETCH_RECIPE':
return action.payload;
default:
return state;
}
};
export default combineReducers({
recipes: recipeReducer
});
import React from 'react';
import { connect } from 'react-redux';
import { fetchRecipe } from '../actions';
class Recipe extends React.Component {
componentDidMount() {
this.props.fetchRecipe();
console.log("This doesn't work", this.props.recipes)
}
renderList() {
return this.props.recipes.map(recipe => {
return (
<div>
<p>{recipe.publisher}</p>
</div>
)
})
}
render() {
console.log("First loaded: empty, second time: data fetched", this.props.recipes)
return (
<div>
{this.renderList()}
</div>
);
}
}
const mapStateToProps = (state) => {
return { recipes: state.recipes }
};
export default connect(mapStateToProps,{
fetchRecipe
})(Recipe);
API Request
import axios from 'axios';
import { key } from './config';
export default axios.create({
baseURL: `https://cors-anywhere.herokuapp.com/https://www.food2fork.com/api/search?key=${key}&q=pizza`
});
I'm trying to learn redux-observables but I seem to be having an issue getting my app to return data. I keep getting the error below and I'm not sure where I'm going wrong or what the error actually means.
Error: TypeError: axios__WEBPACK_IMPORTED_MODULE_3___default.a.get(...).map is not a function
Actions:
import { FETCH_DATA, FETCH_DATA_FAIL } from './constants';
export const fetchData = exampleData => ({
type: FETCH_DATA,
payload: { exampleData }
});
export const fetchDataFail = () => ({
type: FETCH_DATA_FAIL
});
EPIC:
import 'rxjs';
import { FETCH_DATA, FETCH_DATA_FAIL } from './constants';
import { fetchData } from './actions';
import axios from 'axios';
import { Observable } from 'rxjs';
import { mergeMap } from 'rxjs/operators';
import { ofType } from 'redux-observable';
export const exampleEpic = action$ =>
action$.pipe(ofType(FETCH_DATA),
mergeMap(action =>
axios.get('https://jsonplaceholder.typicode.com/todos/1')
.map(response => fetchData(response))
.catch(error => Observable.ofType(FETCH_DATA_FAIL)))
);
REDUCER:
import { FETCH_DATA, FETCH_DATA_FAIL } from './constants';
import { combineReducers } from 'redux';
const initialState = {};
export const exampleData = (state = initialState, action) => {
switch (action.type) {
case FETCH_DATA:
return action.payload
case FETCH_DATA_FAIL:
return {};
default:
return state;
}
};
export default combineReducers({
exampleData
});
EXAMPLE COMPONENT:
import React, { Component } from 'react';
import { connect } from 'react-redux';
import { fetchData } from './actions';
class App extends Component {
onClick = ()=>{
this.props.fetchData();
}
render() {
return (
<div>
<button onClick={this.onClick}><h1>Hello World</h1></button>
{JSON.stringify(this.props.data) }
</div>
);
}
}
const mapStateToProps = (state) => {
return {
data: state
}
};
function mapDispatchToProps(dispatch) {
return {
fetchData: () => dispatch(fetchData())
}
};
export default connect(
mapStateToProps,
mapDispatchToProps
)(App);
Using .then would have solved the issue, by the right way of doing it is using rxjs's from function, like below
import 'rxjs';
import { FETCH_DATA, FETCH_DATA_FAIL } from './constants';
import { fetchData } from './actions';
import axios from 'axios';
import { Observable, from } from 'rxjs';
import { mergeMap, map } from 'rxjs/operators';
import { ofType } from 'redux-observable';
export const exampleEpic = action$ =>
action$.pipe(ofType(FETCH_DATA),
mergeMap(action =>
from(axios.get('https://jsonplaceholder.typicode.com/todos/1'))
.map(response => fetchData(response))
.catch(error => Observable.ofType(FETCH_DATA_FAIL)))
);
Also, make sure you import .map operator from rxjs
Update: syntax using the .pipe operator
export const exampleEpic = action$ =>
action$.pipe(
ofType(FETCH_DATA),
mergeMap(action => from(axios.get('https://jsonplaceholder.typicode.com/todos/1/'))
.pipe(
map(response => fetchData(response)),
catchError(() => of(fetchDataFailure()))
)
)
)