Reducer is not adding object to array, null is added instead

Question

For practice with Redux, I have in index.js

const state = [
  {
    resort: 'Jay Peak',
    date: '2018-2-22',
    powder: true,
    backcountry: false,
  },
];

const action = {
  type: constants.ADD_DAY,
  payload: {
    resort: 'Mad River Glen',
    date: '2018-3-14',
    powder: true,
    backcountry: false,
  },
};

const nextState = allSkiDays(state, action);

console.log(`

  initial state: ${JSON.stringify(state)}
  action: ${JSON.stringify(action)}
  new state: ${JSON.stringify(nextState)}

  `);

and my reducers for composition,

export const skiDay = (state = [], action) => {
  action.type === constants.ADD_DAY ? action.payload : state;
};

export const allSkiDays = (state = [], action) => {
  switch (action.type) {
    case constants.ADD_DAY:
      return [...state, skiDay(null, action)]; // COMPOSITION!!!! use skiDay()
    default:
      return state;
  }
};

and I keep getting this result,

  initial state: [{"resort":"Jay Peak","date":"2018-2-22","powder":true,"backcountry":false}]
  action: {"type":"ADD_DAY","payload":{"resort":"Mad River Glen","date":"2018-3-14","powder":true,"backcountry":false}}
  new state: [{"resort":"Jay Peak","date":"2018-2-22","powder":true,"backcountry":false},null]

I've tried many things why is null still being spread onto the array and not the new object?

You might want to put a return before action.type, or remove the curly brackets in the function skiDay. — gargsms
– gargsms, Commented Aug 8, 2018 at 18:05

Danny Delott · Accepted Answer · 2018-08-08 18:05:14Z

1

This reducer is not returning the next state.

export const skiDay = (state = [], action) => {
  action.type === constants.ADD_DAY ? action.payload : state;
};

Do this instead:

export const skiDay = (state = [], action) => {
  return action.type === constants.ADD_DAY ? action.payload : state;
};

answered Aug 8, 2018 at 18:05

Danny Delott

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1 Comment

Kevin T. Over a year ago

I thought that in this case the arrow function implicitly returns. I realize it was the curly braces the called for the return keyword. thanks

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