How do I update array inside object in redux

Question

I have an array I'm writing a code for redux now.

const initialState = [{ id: '1', title: '', description: '' }];

I would like to update that array like this

[{ id: '1', title: '', description: '' },{ id: '2', title: '', description: '' }];

and after copying I want to update the copy one of id to '2'

here is what I tried

    case COPY_QUESTION: {
      const copyQuestion = state.find(question => question.id === action.payload)
      copyQuestion?.id = (state.length + 1).toString()
      return [...state, copyQuestion];
    }

it didn't work for me. if I try to change id, the 0 index changes too at the same time. like this

[{ id: '2', title: '', description: '' },{ id: '2', title: '', description: '' }];

I would really appreciate your help thanks for reading this question.

score 0 · Answer 1 · answered Mar 31 '22 at 07:33

0

Something like this should work:

const initialState = [{ id: '1', title: '', description: '' }];

const copyInitialState = [...initialState]

copyInitialState.push({ id: parseInt(copyInitialState[copyInitialState.length - 1].id, 10) + 1, title: '', description: '' })

//setState

copyInitialState is then equal to:

[
 {
  id:"1",
  title:"",
  description:""
 },
 {
  id:2,
  title:"",
  description:""
 }
]

answered Mar 31 '22 at 07:33

Reinier68

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can I use array.push in redux? – icdeverything Mar 31 '22 at 07:38
You can if you first make a copy of the array of objects you are trying to update --> `const copyInitialState = [...initialState]` – Reinier68 Mar 31 '22 at 07:40

score 0 · Accepted Answer · answered Mar 31 '22 at 07:38

JavaScript handels Objects by reference and therefore ’find’ only returns the address in memory of the already existing object, which you then manipulate.

You have to clone your object first, e.g. using the spread operator (not for deep clones):

const originalQuestion = state.find(question => question.id === action.payload)
const copyQuestion = { ...originalQuestion }

Have a look at this SO question for more context and possibilities.

How do I update array inside object in redux

2 Answers2