Cannot update component on props or state change

Question

I want browser to show EditMessage component (in Dashboard.js ) if showEdit is true (see initState in MessageReducer.js ) and CreateMessage component if showEdit is false but my code doesn't work. My app is not noticing state or props change in Dashboard.js .

I tried including this.setState method in Dashboard.js but I am getting an error: "Maximum update depth exceeded. This can happen when a component repeatedly calls setState inside componentWillUpdate or componentDidUpdate". I also tried to assign the value of showTypeForm directly to props and output it (see comments in Dashboard.js ) but this approach didn't work either. I am not sure what lifecycle method to use.

My code looks like this. MessageSummary.js:

 import React, { Component } from 'react';
 import { connect } from 'react-redux';
 class MessageSummary extends Component {
    editClick = (e) => {
       e.preventDefault();
       this.props.editMessage('123', 'I love web development'); //test values
    }
    render() {
       return (
          <button className="edit-message" onClick={this.editClick}>Edit 
          Message</button> // this button changes showEdit in MessageReducer.js
       )
    }
 }
 const mapDispatchToProps = (dispatch) => {
    return {
       editMessage: (id, newMessage) => dispatch(editMessage(id, newMessage))
    }
 }
 export default connect(null, mapDispatchToProps)(MessageSummary); 

MessageActions.js:

export const editMessage = (id, newMessage) => {
  return (dispatch, getState, { getFirebase, getFirestore }) => {
    dispatch({
      type: "EDIT_MESSAGE"
    });
  }
}

RootReducer.js:

// importing everything
const rootReducer = combineReducers({
  message: messageReducer
});
export default rootReducer;

MessageReducer.js:

const initState = {
  showEdit: false
};
const messageReducer = (state = initState, action) => {
  switch (action.type) {
     case 'EDIT_MESSAGE':
         initState.showEdit = !initState.showEdit; // toggling showEdit
         return state;
     default:
        return state;
     }
  }
 export default messageReducer;

Dashboard.js:

// importing everything
class Dashboard extends Component {
   state = {
      showEdit: this.props.message.showEdit
   }

   render() {
      const { message } = this.props; // destructuring

      // this.setState({
        //  showEdit: message.showEdit
      // })

      // const showTypeForm = message.showEdit ? <EditMessage /> : <CreateMessage />;

      return (
        <div className="message-form">   
            {this.state.showEdit ? <EditMessage /> : <CreateMessage />}
            // {showTypeForm }
        </div>   
      )
    }
   const mapStateToProps = (state) => {
      return {
         message: state.message
      }
   }
 }
 export default connect(mapStateToProps)(Dashboard); 

Answer 1

There is something wrong in your reducer 'MessageReducer.js'. Here your directly mutating the 'initState' value which is against the reducer function specificataion. It should be a pure function and should not mutate the state, every time it should return a new state object.

const initState = {
  showEdit: false
};
const messageReducer = (state = initState, action) => {
  switch (action.type) {
     case 'EDIT_MESSAGE':
         let updatedState = Object.assign({},state,{showEdit:!state.showEdit}) ;
         return updatedState;
     default:
        return state;`enter code here`
     }
  }
 export default messageReducer;

Answer 2

You are not updating the state as the props changes, you need to do that in componentDidUpdate with a condition so that it doesn't stuck in infinite loop( "Maximum update depth exceeded). I hope this helps.

Writing this.setState inside render will make you stuck in infinite loop reason being whenever the state changes component renders again.

class Dashboard extends Component {
   state = {
      showEdit: this.props.message.showEdit
   }
   componentDidUpdate(prevProps){
   if(this.props.message !== prevProps.message){
       this.setState({
        showEdit: this.props.message.showEdit
       })
     }
   }
   render() {
      const { message } = this.props; // destructuring

      // this.setState({
        //  showEdit: message.showEdit
      // })

      // const showTypeForm = message.showEdit ? <EditMessage /> : <CreateMessage />;

      return (
        <div className="message-form">   
            {this.state.showEdit ? <EditMessage /> : <CreateMessage />}
            // {showTypeForm }
        </div>   
      )
    }
   const mapStateToProps = (state) => {
      return {
         message: state.message
      }
   }
 }
 export default connect(mapStateToProps)(Dashboard);