Component does not rerender when context changes - reactjs

Question

I've been playing around with the react context api and I'm just not getting why it's not working.
I have a component with a container that should show or hide depending on a valuer stored in context.
This is the component:
import React, { useContext } from 'react';
import ResultsContext from '../../context/results/resultsContext';
const ResultsPanelContainer = () => {
const resultsContext = useContext(ResultsContext);
const { showResults } = resultsContext;
console.log('showResults in ResultsPanelConatiner: ', showResults);
return (
<div
className='container-fluid panel'
style={{ display: showResults ? 'block' : 'none' }}
>
<div className='container'>
<div className='row'>
<div className='col'>
<h1 className='display-4'>Results.Panel.js</h1>
</div>
</div>
</div>
</div>
);
};
export default ResultsPanelContainer;
For completeness, the context is divided up into three sections, the call to the context itself, a 'state' file and a reducer. These are displayed below:
resultsContext.js
import { createContext } from 'react';
const resultsContext = createContext();
export default resultsContext;
ResultsState.js
import React, { useReducer } from 'react';
// import axios from 'axios';
import ResultsContext from './resultsContext';
import ResultsReducer from './resultsReducer';
import { UPDATE_SHOW_RESULTS } from '../types';
const ResultsState = (props) => {
const initialState = {
showResults: false,
};
const [state, dispatch] = useReducer(ResultsReducer, initialState);
const updateShowResults = (data) => {
console.log('updateShowResults - ', data);
dispatch({
type: UPDATE_SHOW_RESULTS,
payload: data,
});
};
return (
<ResultsContext.Provider
value={{
showResults: state.showResults,
updateShowResults,
}}
>
{props.children}
</ResultsContext.Provider>
);
};
export default ResultsState;
resultsReducer.js
import { UPDATE_SHOW_RESULTS } from '../types';
export default (state, action) => {
switch (action.type) {
case UPDATE_SHOW_RESULTS:
return {
...state,
showResults: action.payload,
};
default:
return state;
}
};
The change is triggered by a button click in a separate component and this does trigger an update in the context as shown when you log it to the console. However, the component is not rerendering.
I understand from reading various answers on here that changing context doesn't trigger a rerender of all child components in the same way that setState does. However, the component displaying this is calling the context directly so as far as I can see the rerender should take effect.
Am I missing something glaringly obvious?
Thanks in advance.
Stef

Answer 1

Forget the above... I'm an idiot - wrapped the two separate parts of the app in two separate instances of ResultsState which weren't communicating. Did this:
const App = () => {
return (
<Fragment>
<UsedDataState>
<Header />
</UsedDataState>
<main>
<ExportPanelContainer />
<ResultsState>
<SendQueryState>
<OrQueryState>
<AndQueryState>
<QueryPanelContainer />
</AndQueryState>
</OrQueryState>
</SendQueryState>
</ResultsState>
<ResultsState>
<ResultsPanelContainer />
</ResultsState>
</main>
</Fragment>
);
};
Instead of this:
const App = () => {
return (
<Fragment>
<UsedDataState>
<Header />
</UsedDataState>
<main>
<ExportPanelContainer />
<ResultsState>
<SendQueryState>
<OrQueryState>
<AndQueryState>
<QueryPanelContainer />
</AndQueryState>
</OrQueryState>
</SendQueryState>
<ResultsPanelContainer />
</ResultsState>
</main>
</Fragment>
);
};
Hope this is useful for someone else...