为什么这不改变我的redux状态？

Question

I have an array of array of objects in my state. What I want to do is find the question with the correct id, then find the answer with the correct id to change it's value and update it to the state.

Here is what I got:

function updateObject(oldObject, newValues) {
  return Object.assign({}, oldObject, newValues);
}

function updateItemInArray(array, questionId,answerId, updateItemCallback) {
  const getQuestion = array.map(item => {
    if(item.id !== questionId) {
      return item;
    }
  })
  const updatedItem = getQuestion[0].answers.map(answer => {
    if(answer.id !== answerId) {
      return answer;
    }
​
    const updatedItem = updateItemCallback(answer);
    return updatedItem;

  });
​
  return updatedItems;
}



export function answerUpdate(state = [], action){
  switch(action.type){
    case 'ANSWER_UPDATE_FETCH_SUCCESS': {
      const newAnswer = updateItemInArray(state.project, action.questionId, action.answerId, answer => {
        return updateObject(answer, {value : action.newValue});
      });
    }
  }
}

the object I'm looking through is kinda obvious but it looks something like this

project = [
  question = {
    id:"some Id",
    answers:  [
    {
      id:"another id",
      value="someValue"
    }
    ]
  }
]

and some other properties but it is unrelevant for this question. Thankful for every answer!

Answer 1

You need to update data in map itself instead of creating variable, map function returns new array with updated value and you are updating 0th index of array which won't be one you're looking for.

function updateItemInArray(array, questionId,answerId, newValue) {
  return array.map(item => {
      if(item.id !== questionId) {
        return item;
      } else {
        item.answers.map(answer => {
          if(answer.id !== answerId) {
            return answer;
          } else {
            updateObject(answer, { value : newValue})
          }
        });
      }
    });
}

export function answerUpdate(state = [], action){
  switch(action.type){
    case 'ANSWER_UPDATE_FETCH_SUCCESS': {
      return updateItemInArray(state, action.questionId, action.answerId, action.newValue);
    }
  }
}