Unable to Update State ReduxToolkit - reactjs

Question

I have a array of objects kept in my state, I want to be able to edit one of the objects in the array and update the state.
However, I cannot seem to update anything with the state except push more items into it.
I am using #reduxjs/toolkit and the createSlice() method for my reducers.
Here is my slice, it has some logic to pull the initial state array from an API.
import { createSlice, createAsyncThunk } from '#reduxjs/toolkit';
import { BACKEND_API } from "../../utilities/environment";
import fetchViaApi from "../../utilities/fetchViaApi";
export const getInitialDashboards = createAsyncThunk(
'dashboard/getDashboards',
async () => {
const response = await fetchViaApi('/dashboards', {
baseUrl: BACKEND_API,
method: "GET"
});
const data = await response.json();
return data;
}
)
const initialState = [];
const dashboardsSlice = createSlice({
name: 'dashboards',
initialState,
reducers: {
setDashboards: (state,action) => {
state = action.payload;
},
updateDashboard: (state,action) => {
// state.push(action.payload);
state = [...state.slice(0, 5)];
},
deleteDashboard: (state, action) => {
},
},
extraReducers: builder => {
builder.addCase(getInitialDashboards.fulfilled, (state, action) => {
action.payload.forEach(element => {
state.push(element);
});
})
}
});
export const { setDashboards, updateDashboard, editDashboard, deleteDashboard } = dashboardsSlice.actions;
export default dashboardsSlice.reducer;
The commented out state.push(action.payload) works fine, but sometimes I don't want to add new object to the array, but edit existing ones.
My thought was to slice the existing element out and add the new version back to the array. But I cannot slice the state.
I am using Redux DevTools in Chrome and watching the state not change after calling updateDashboard, there were 10 elements after getDashboards is completed.

Answer 1

You had the right idea, but your reducers need to be returning the new state, not assigning it.. e.g.
reducers: {
setDashboards: (state,action) => {
return action.payload;
},
updateDashboard: (state,action) => {
return [...state.slice(0, 5)];
},
deleteDashboard: (state, action) => {
return [];
},
},

Answer 2

The issue is that state = anything is not a valid way to update data with Immer. It's not mutating the existing state, and it's not returning a new value - it just points the local state variable to something else, so Immer has no way to know that anything changed.
If you want to replace the existing state entirely, do return newStateValue. If you want to update part of the state, then mutate a nested field or value.
See the Writing Reducers with Immer page in the RTK docs for more details.

Answer 3

I faced a similar problem today. Updating or assigning values to the state directly is not working. But updating the properties inside the state variable works
I would add a property named dashboards to the state and update it instead of updating the state directly in reducer
Redux toolkit is using immer under the hood. It might be helpful to take a look at immer and get an idea to mutate the state