Redux Reducer build object without function

Question

I can successfully do the following which allows me to build an object of profiles with userid's as the key - I like this structure as it helps with other parts of the application

function profilesMembersResponseConcat(members, newMember) {
    members[newMember.userid] = newMember
    return  members
}

[C.PROFILES_MEMBERS_RESPONSE]: (state, { payload }) => ({
    ...state,
    profilesMembersResponse: profilesMembersResponseConcat(state.profilesMembersResponse, payload)
}),

Question: Is there a way however to do this without the need for a function. I've tried below but I get an error message: "Arrow function should not return assignment."

[C.PROFILES_MEMBERS_RESPONSE]: (state, { payload }) => ({
    ...state,
    profilesMembersResponse: state.profilesMembersResponse[payload.userid] = payload
}),

Why not using the function? It seems cleaner and also what you're doing on the second snippet is mutating the current state which is not a good practice. — Amin Paks
– Amin Paks, Commented Dec 1, 2019 at 1:36
good call on the mutating state... I was just interested to see if I could do this without a separate function... — Adam
– Adam, Commented Dec 1, 2019 at 1:51

JoshD · Accepted Answer · 2019-12-01 02:42:26Z

1

Both of your solutions are mutating the object. You'll want to change your assignment to something more like:

[C.PROFILES_MEMBERS_RESPONSE]: (state, { payload }) => ({
  ...state,
  profilesMembersResponse: ({...state.profilesMembersResponse, [payload.userid]:payload})
}),

answered Dec 1, 2019 at 2:42

JoshD

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