React / Redux: Correct way to update object in reducer - reactjs

Question

I'm having trouble updating an object in my React / Redux reducer. The initial state is an object of Immutable. I'm stuck trying to update the object.
import Immutable from 'immutable';
import * as actionTypes from '../actions/actionTypes';
const initialState = Immutable.fromJS({
user: {
id: null,
name: null,
age: null
}
});
export default function addUserReducer(state = initialState, action) {
switch(action.type) {
case actionTypes.ADD_USER:
const user = {
id: action.id,
name: action.name,
age: action.age
}
return state.setIn(['user'], user);
default:
return state;
}
}
The state always returns a map with the values of id, name and age as null.
What's the correct way to update the state in my reducer?

Answer 1

Use merge function in immutable to change the state.It can be implemented like this
import Immutable from 'immutable';
import * as actionTypes from '../actions/actionTypes';
const initialState = Immutable.fromJS({
user: {
id: null,
name: null,
age: null
}
});
export default function addUserReducer(state = initialState, action) {
switch(action.type) {
case actionTypes.ADD_USER:
// This will update the state in the reducer if you are using immutable library
return state.merge({
id: action.id,
name: action.name,
age: action.age
});
default:
return state;
}
}

Answer 2

Your code looks ok, and when I run it in a repl it works.
I tested it by adding the following:
const newState = addUserReducer(undefined, {
type: 'ADD_USER', // I just assumed that's what your type resolves to.
id: 1,
name: 'FOO',
age: 100,
});
console.log(newState); // Logs "Map { "user": [object Object] }"
console.log(Immutable.Map.isMap(newState); // true
console.log(Immutable.Map.isMap(newState.get('user'))) //false
I suspect the reason it's not working for you is because your action's actual type does not actually equal actionTypes.ADD_USER. I would double check that case in the reducer runs. A simple log in that case should tell you.
Also, like other comments have said above, right now your ADD_USER case is setting the user as a NON-Immutable object, so instead modify the ADD_USER return statement like so:
state.set('user', Immutable.Map(user));
Also note that since 'user' is a top-level key, Maps .set method works just fine.