One of the challenges when working with redux in larger applications is managing complex state structures. As an application grows, you might find yourself needing multiple redux stores to handle different aspects of your application state. However, managing multiple stores can become cumbersome and hinder the scalability of your application. In this article, we will explore a technique for combining multiple redux stores into a single store, allowing for a more organized and scalable application structure.

The Problem with Multiple Redux Stores

By default, a redux application typically has a single store that contains the entire application state. This works well for smaller applications or applications with simple state structures. However, as your application grows, it may become necessary to split your state into multiple stores for better organization and modularity. For example, you might have a store for authentication, another store for user preferences, and yet another store for managing UI state.

While this approach can provide better separation of concerns, it can also lead to challenges. The main drawback of multiple redux stores is that it becomes harder to share state between them. With a single store, you have access to the entire application state via selectors. However, with multiple stores, you need to manually coordinate the flow of data between them, which can quickly become complex and error-prone.

Combining Stores with Redux Toolkit

Redux Toolkit, the official toolkit maintained by the Redux team, provides a solution for combining multiple redux stores into a single store. The createSlice and createAsyncThunk APIs of Redux Toolkit allow us to define multiple slices of state, each with its own reducer, actions, and selectors. We can then combine these slices into a single store using the combineReducers function provided by Redux Toolkit.

Here’s an example of how this can be done:

// authSlice.js
import { createSlice } from '@reduxjs/toolkit';

const authSlice = createSlice({
  name: 'auth',
  initialState: { isLoggedIn: false },
  reducers: {
    login: state => { state.isLoggedIn = true },
    logout: state => { state.isLoggedIn = false }
  }
});

export const { login, logout } = authSlice.actions;
export const selectIsLoggedIn = state => state.auth.isLoggedIn;

export default authSlice.reducer;

// preferencesSlice.js
import { createSlice } from '@reduxjs/toolkit';

const preferencesSlice = createSlice({
  name: 'preferences',
  initialState: { theme: 'light' },
  reducers: {
    setTheme: (state, action) => { state.theme = action.payload }
  }
});

export const { setTheme } = preferencesSlice.actions;
export const selectTheme = state => state.preferences.theme;

export default preferencesSlice.reducer;

// store.js
import { configureStore, combineReducers } from '@reduxjs/toolkit';
import authReducer from './authSlice';
import preferencesReducer from './preferencesSlice';

const rootReducer = combineReducers({
  auth: authReducer,
  preferences: preferencesReducer
});

const store = configureStore({ reducer: rootReducer });

export default store;

In this example, we have two slices of state - auth and preferences. Each slice has its own reducer, actions, and selectors defined using the createSlice API. The reducers are combined into a single root reducer using the combineReducers function. This root reducer is then passed to the configureStore function to create the redux store.

Now, we can use the login, logout, setTheme, selectIsLoggedIn, and selectTheme functions in our components to interact with the combined store. The state of each slice is automatically namespaced under the corresponding slice name (auth and preferences in this case).

Conclusion

Managing multiple redux stores is a common challenge when building larger applications. However, by using the powerful features of Redux Toolkit, we can combine multiple stores into a single store, providing a more scalable and organized application structure. This approach allows for better state sharing between different parts of the application and simplifies the overall management of the state.

By adopting this technique, you can improve the scalability and maintainability of your redux-based application, making it easier to build and extend as your project grows.

#Redux #ReduxToolkit