Redux Store populates in getInitialProps but is empty on client - reactjs

Question

I'm using the Redux Thunk example template. When I dispatch an action in getInitialProps, that populates my store, the data is loaded but after the page is rendered, the store is still empty.
static async getInitialProps({ reduxStore }) {
await reduxStore.dispatch(fetchCategories())
const categories = reduxStore.getState().programm.categories;
console.log('STATE!!!', categories)
return { categories }
}
The categories will load correctly but when I inspect my store, the categories state is empty.
Here is my store:
import db from '../../api/db'
// TYPES
export const actionTypes = {
FETCH_PROGRAMMS: 'FETCH_PROGRAMMS',
FETCH_CATEGORIES: 'FETCH_CATEGORIES'
}
// ACTIONS
export const fetchCategories = () => async dispatch => {
const categories = await db.fetchCategories();
console.log('loaded Cate', categories)
return dispatch({
type: actionTypes.FETCH_CATEGORIES,
payload: categories
})
}
// REDUCERS
const initialState = {
programms: [],
categories: []
}
export const programmReducers = (state = initialState, action) => {
switch (action.type) {
case actionTypes.FETCH_PROGRAMMS:
return Object.assign({}, state, {
programms: action.payload
})
case actionTypes.FETCH_CATEGORIES:
console.log('Payload!', action);
return Object.assign({}, state, {
categories: action.payload
})
default:
return state
}
}
How can I make the redux state loaded on the server (in getInitialProps) be carried over to the client?

Answer 1

After hours of searching for solution it seems like I found my problem. It seems like I need to pass an initialState when creating the store. So instead of this:
export function initializeStore() {
return createStore(
rootReducers,
composeWithDevTools(applyMiddleware(...middleware))
)
}
I'm doing this and it works now
const exampleInitialState = {}
export function initializeStore(initialState = exampleInitialState) {
return createStore(
rootReducers,
initialState,
composeWithDevTools(applyMiddleware(...middleware))
)
}

Answer 2

If you do this:
return { categories }
in getInitialProps, categories should be available in component's props in client side.
It should be available in Redux as well, this could cause the problem:
return Object.assign({}, state, {
categories: action.payload
})
Take a look at this Object.assign, the function only takes 2 parameters.
My normal way of doing this:
return {
...state,
categories: action.payload,
};