React Redux Store updating, but component not re-rendering

Question

Using the terminal to test my dispatched actions, Redux-logger shows that my state is being correctly updated. However, my component is not re-rendering as a result of the state change. I've looked at the SO answers regarding component not re-rendering, a majority of the responses claim that the state is being mutated; as a result, Redux won't re-render. However, I'm using Lodash's merge to deep-dup an object, I'm pretty sure I'm not returning a modified object. (Please see attached snippet below)

Would love to hear some advice from you guys, pulling my hair out on this one!

const usersReducer = (state = {}, action) => {
  Object.freeze(state); // avoid mutating state

  console.log(state); 
  // returns an empty object  
  let newState = merge({}, state);
  console.log(newState); 
  // returns my state with my dispatched action object inside  already???
  // newState for some reason already has new dispatched action
  switch (action.type) {
    case RECEIVE_USER:
      let newUser = {[action.user.id] = action.user};
      return merge(newUser, newUser);
    case RECEIVE_USERS:
      newState = {};
      action.users.forEach(user => {
        newState[user.id] = user;
      });
      return merge({}, newState);
    default:
      return state;
  }
};

React Container Component

import { connect } from 'react-redux';
import { receiveUsers, receiveUser, refreshAll, requestUsers, requestUser } from '../../actions/user_actions';
import allUsers from '../../reducers/selectors';
import UserList from './user_list';

const mapStateToProps = (state) => ({
  users: allUsers(state), // allUsers (selector that takes the state specfically the user Object and returns an array of user Objects)
  state
});

const mapDispatchToProps = (dispatch) => ({
  requestUser: () => dispatch(requestUser()),
  requestUsers: () => dispatch(requestUsers()),
  receiveUsers: (users) => dispatch(receiveUsers(users)),
  receiveUser: (user) => dispatch(receiveUser(user)),
  refreshAll: (users) => dispatch(refreshAll(users))
});

export default connect(
  mapStateToProps,
  mapDispatchToProps
)(UserList);

React Presentational component

import React from 'react';

class UserList extends React.Component {
  render() {
    const { users, state } = this.props;

    const userItems = users.map((user, idx) => {
        return(<li key={idx}>{user.username}</li>);
    });

    return (
      <div>
        <ul>
          { userItems }
        </ul>
      </div>
    );
  }
}

export default UserList;

React Store

import { createStore, applyMiddleware } from 'redux';
import createLogger from 'redux-logger';
import RootReducer from '../reducers/root_reducer';

const logger = createLogger();
const configureStore = (preloadedState = {}) => {
  return createStore(
    RootReducer, 
    preloadedState,
    applyMiddleware(logger));
};

// const configureStore = createStore(rootReducer, applyMiddleware(logger));

// oddly enough, when I have the store as a constant and not a function that returns the store constant, dispatching actions through the terminal will correctly update the state and rerender the component 

export default configureStore;

React Selector

const allUsers = ({ users }) => {
  return Object.keys(users).map(id => (
    users[id]
  ));
};

export default allUsers;

Answer 1

I had a similar problem, just in case someone stumbles upon this, I needed to clone the array in order to re-render the view:

export const addFieldRow = () => (
    (dispatch: any, getState: any) => {
        const state = getState();
        const myArrayOfObjects = myArrayOfObjectsProp(state);
        const newObject = {
            key: "",
            value: "",
        };
        myArrayOfObjects.push(newObject);
        dispatch(addFieldRowAction({ myArrayOfObjects: [...myArrayOfObjects] })); <== here
    }
);

Answer 2

I use this solution to do it. I put the users on my state and update it on any change, with componentWillReceiveProps. Hope it helps :-)

class UserList extends React.Component {
    constructor(props) {
       super(props);
       console.log(this.props);
       this.state = {
          users: props.users
       };
    }
    componentWillReceiveProps(nextProps) {
        if (this.props.users !== nextProps.users) {
            this.setState({
                users: nextProps.users,
            });
        }
    }

  render() {
    const { users } = this.state;

    const userItems = users.map((user, idx) => {
        return(<li key={idx}>{user.username}</li>);
    });

    return (
      <div>
        <ul>
          { userItems }
        </ul>
      </div>
    );
  }
}

export default UserList;

Answer 3

Common problem in this case is using not reactive operations for changing state. For example use concat() for array, but not push() and so on.

Answer 4

What do your React components look like? Are you using internal state in them or props to push the data down. Usually I see the issue is with people setting the internal state of props with Redux state. You should be pushing props down to the components and they will re-render on update.

Also, check out https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi?hl=en

to see if the props are really changing.

Answer 5

Create new copy of array from the prop state to re-render the component

render() {

const {allPost} = this.props;
//Use the spread operator to create a new copy of the array
const posts = [...allPost];

 const plansList = () => {
     return posts.length < 1 ? null : posts && <PlansList allPost={posts} 
   />;
 };

return (
  <>
    <Container className="mt-lg-5 pt-lg-5">
    {plansList()}
  </Container>
  </>
);
}

Answer 6

i spent lot of time to find out that when using more than 1 reducer (with combineReducers), then your mapStateToProps should point the correct reducer names, for example

const mapStateToProps = state => ({
  someVar: state.yourReducerName.someVar,
  loading: state.yourReducerName.loading,
  error: state.yourReducerName.error
});