mapStateToProps 不更新具有切换状态的组件

Question

new user to Redux so apologies for any silly mistakes. Ultimately, I am trying to toggle a className in component B as an onClick function toggles a state in component A.

So it should be: Component A button click => state toggles => Component B className toggles.

I have setup my store and my mapDispatchToProps function that changes the state in my store seems to be working. However, calling this state in a different component is working... but, does not re-render as the state in the store toggles. There is more content in my code, but I've tried to strip the parts that are not necessary to this issue.

Component A - containing a button that toggles a state and changes a state within my store/rootReducer:

import React from 'react';
import { connect } from 'react-redux';


function Nav(props) {
  const [showMenu, setShowMenu] = React.useState('menuClosed');

  function menuClick() {
    showMenu === 'menuClosed' ? setShowMenu('menuOpen') :
      setShowMenu('menuClosed');
  }

  // this works fine, I know this due to the console.log on my rootReducer page:
  React.useEffect(() => {
    props.toggleMenu(showMenu);
  }, [showMenu])


  return (
    <button className="hvr-icon-grow-rotate" id="bars" onClick={() => { menuClick(); }}>
      <FontAwesomeIcon icon={faBars} className="hvr-icon" />
    </button>
  )
}

const mapStateToProps = (state) => {
  return {
    menu: state.menu
  }
}

const mapDispatchToProps = (dispatch) => {
  return {
    toggleMenu: (showMenu) => {
      dispatch({ type: 'TOGGLE_MENU', menu: showMenu })
    }
  }
}

export default connect(mapStateToProps, mapDispatchToProps)(Nav)

Component B: supposed to toggle a className depending on store state:

import React from 'react';
import { connect } from 'react-redux';

const [noHover, setNoHover] = React.useState('projectGrid');

  React.useEffect(() => {
    console.log('portfolio props: ' + props.menu + ' noHover: ' + noHover);
    if (props.menu === 'menuOpen') {
      setNoHover('projectGrid noHover');
      console.log('portfolio props: ' + props.menu + ' noHover: ' + noHover);
    }
    else if (props.menu === 'menuClosed') {
      setNoHover('projectGrid');
      console.log('portfolio props: ' + props.menu + ' noHover: ' + noHover);
    }
  }, [])

  return (<div className={noHover}>some content</div>);
}

const mapStateToProps = (state) => {
  return {
    menu: state.menu
  }
}

export default connect(mapStateToProps)(PortfolioItem)

finally, content of my rootReducer.js page, or the Redux store:

const initState = {
  menu: ['menuClosed']
}

const rootReducer = (state = initState, action) => {
  console.log(action);
  return state;
}

export default rootReducer;

Any help would be greatly appreciated - thank you!

Answer 1

It doesn't look like you're actually toggling anything in your reducer.

You need to return a new state if you want it to change. I'm not sure exactly how it should look in your case, but something like this:

const rootReducer = (state = initState, action) => {
  let newState = {...state}; // Create a new state object so we don't mutate original
  switch(action.type) { // Check what type was sent to see if we should update
    case 'TOGGLE_MENU':
      newState.menu = action.menu; // Set new state based on action
      return newState;
    default:
      return state; // Return old state if nothing changed
  }
}

Side note: it looks like your initial state has menu as an array, but your components don't treat it as one. It seems like it should be defaulted to a string.

Answer 2

It looks like @brian-thompson has solved your problem, so I won't solve it again, but I would say you can make your styling logic a log easier by using the classnames library.

Your useEffect callback would be replaced with

const { menu } = props
const noHover = classNames({
  'projectGrid': true,
  'noHover': menu === 'menuOpen'
})

Removing the need for any hooks.