Question

在Immutable.js中，如何通过索引从列表中获取对象并设置属性，然后更新整个列表。

状态是一个名为artists的对象数组。

[{ id: 1, selected: false}, { id: 2, selected: false}]

现在我希望在索引0处设置selected = true

我试过了：

  const artistItem = state.get(action.payload.index).set({ selected: true });
  const artists = state.get('artists').set(action.payload.index, artistItem);

如何在不覆盖其他属性的情况下实现这一目标？

Answer 1

如果您的州确实看起来像

[{ id: 1, selected: false}, { id: 2, selected: false}]

我相信你想使用List#update：

let state = Immutable.fromJS([
    {id: 1, selected: false},
    {id: 2, selected: false}
]);

state = state.update(0, (artist) => artist.set('selected', true));
console.log(state); // [{id: 1, selected: true}, {id: 2, selected: false}]

// Note that this is equivalent to:
state = state.set(0, state.get(0).set('selected'));

但是从您的代码中看起来您的状态看起来更像是

{ artists: [{ id: 1, selected: false}, { id: 2, selected: false}] }

如果是这种情况，您需要使用Map#updateIn：

let state = Immutable.fromJS({
    artists: [
       {id: 1, selected: false},
       {id: 2, selected: false}
    ]
});

state = state.updateIn(['artists', 0], (artist) => artist.set('selected', true));
console.log(state); //{artists: [{id: 1, selected: true}, {id: 2, selected: false}]

// Note that this is equivalent to:
state = state.set(
  'artists',
  state.get(artists).set(
    0,
    state.get(artists).get(0).set('selected', true)
));

Answer 2

修改

ImmutableList.set()返回包含更改的另一个列表。这是修改项目的正确方法：

const index = action.payload.index const newArtists = state.set(index, { ...state.get(index), selected: true }); ...

如何通过索引immutable.js获取对象

2 个答案: