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reactjsreduxredux-saga

Before running a Saga, you must mount the Saga middleware on the Store using applyMiddleware with redux tool


Can someone help with this,
Error: Before running a Saga, you must mount the Saga middleware on the Store using applyMiddleware

Mounted sagaMiddleware still it throw an error on the page
Added redux-saga to Store with saga Middleware
Store Js

import { createStore, applyMiddleware, compose } from "redux";
import { persistStore } from "redux-persist";
import createSagaMiddleware from 'redux-saga'
import {fetchCollectionsStart} from './shop/shop.sagas'
import logger from "redux-logger";
import rootReducer from "./root-reducer";

const sagaMiddleware = createSagaMiddleware();

const middlewares = [sagaMiddleware];

if (process.env.NODE_ENV === "development") {
  middlewares.push(logger);
}
const composeEnhancers =
  typeof window === "object" && window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__
    ? window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__({
        // Specify extension’s options like name, actionsBlacklist, actionsCreators, serialize...
      })
    : compose;

const enhancer = composeEnhancers(
  applyMiddleware(...middlewares,sagaMiddleware)
  // other store enhancers if any
);

sagaMiddleware.run(fetchCollectionsStart);

export const store = createStore(rootReducer, enhancer);
export const persistor = persistStore(store);

Created this saga to fetch the collections once the component is mounted
Sagas.js

import {takeEvery} from 'redux-saga/effects';
import ShopActionTypes from './shop.types';

export function* fetchCollectionsAsync(){
    yield console.log('Good');
}
export function* fetchCollectionsStart(){
    yield takeEvery(ShopActionTypes.FETCH_COLLECTIONS_START,
        fetchCollectionsAsync );
}

Solution

  • Make sure you run sagaMiddleware.run(fetchCollectionsStart); after createStore

    const { useState, useEffect } = React;
    const { bindActionCreators, combineReducers, createStore, applyMiddleware, compose } = Redux;
    const { connect, Provider } = ReactRedux;
    const createSagaMiddleware = ReduxSaga.default;
    const { takeEvery } = ReduxSagaEffects;
    const sagaMiddleware = createSagaMiddleware();
    const reducer = (state = {}, action) => {
      return state;
    }
    
    const enhancer = compose(
      applyMiddleware(sagaMiddleware)
    );
    
    const reducers = combineReducers({
      reducer
    })
    
    const store = createStore(
      reducers,
      enhancer
    );
    
    function* fetchCollectionsAsync(){
        yield console.log('Good');
    }
    
    function* fetchCollectionsStart(){
        yield takeEvery('FETCH_COLLECTIONS_START',
            fetchCollectionsAsync );
    }
    
    sagaMiddleware.run(fetchCollectionsStart);
    
    const action = () => ({
      type: 'FETCH_COLLECTIONS_START'
    })
    
    const mapStateToProps = state => ({
      
    })
    
    const mapDispatchToProps = ({
      action
    })
    
    const _App = ({action}) => {
      useEffect(() => {
        action();
      }, [])
      
      return <div>
      </div>
    }
    
    const App = connect(mapStateToProps, mapDispatchToProps)(_App)
    
    ReactDOM.render(
        <Provider store={store}>
          <App />
        </Provider>,
        document.getElementById('root')
      );
    <script src="https://unpkg.com/react/umd/react.development.js"></script>
    <script src="https://unpkg.com/react-dom/umd/react-dom.development.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/babel-polyfill/7.10.1/polyfill.js"></script>
    <script src="https://unpkg.com/babel-standalone@6/babel.min.js"></script>
    <script src="https://unpkg.com/redux@4.0.5/dist/redux.js"></script>
    <script src="https://unpkg.com/react-redux@latest/dist/react-redux.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/redux-saga/1.1.3/redux-saga.umd.js"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/redux-saga/1.1.3/redux-saga-effects.umd.js"></script>
    <div id="root"></div>