Unexpected usage of context prop on connected component

[Shamilik]

Do you want to request a feature or report a bug?
Bug/Unexpected behavior

What is the current behavior?
When passing context prop to connected component, it's replacing original Context and connect() returning an undefined.

Related code line:

react-redux/src/components/connectAdvanced.js

Line 216 in 94799ef

const ContextToUse = this.props.context || Context

Example:
https://codesandbox.io/s/mm039l9q7x

What is the expected behavior?
Not use context prop or document this behavior.

Which versions of React, ReactDOM/React Native, Redux, and React-Redux are you using? Which browser and OS are affected by this issue? Did this work in previous versions of React-Redux?
Latest

[wgao19]

Based on my understanding, v6 allows you to provide a custom context, in which case React-Redux will use your provided context instead of its default one. This allows you to use your own context consumer in your connected components.

You need to pass the same context to both <Provider /> and your connected components.

const MyContext = React.createContext();

// provide to the Provider
<Provider store={store} context={MyContext} />

// provide to all of your connected components
// two ways of doing this:
connect(mapState, mapDispatch, null, { context: MyContext })(MyComponent)
// or
const MyConnectedComponent = connect(mapState, mapDispatch)(MyComponent)
<MyConnectedComponent context={MyContext} />

[markerikson]

Up through v5, store was effectively a "reserved prop name" for the connected wrapper components, as the wrapper interpreted that as "this prop is an alternate Redux store to subscribe to". Similarly, in v6, context is effectively a "reserved prop name", as it's interpreted as "this prop is an alternate React context to read the store state from".

We do need to document this, but this is intentional, and part of the reason for the major version bump.

[brapifra]

It should show a more descriptive error though @markerikson @wgao19

[casdevs]

I‘ve had the same problem and added PR #1134 that helps if the context prop does not contain a valid react context (as in the codesandbox example given above)