当我的状态是数组而不是对象时，如何使用reducer更新状态

Question

我在reducer函数中返回新状态时遇到问题。我的状态是一组对象。每个对象都有两个键值对类别：">和项：[｛｝，｛}，｛｝]。

const initialState = [
{
category: 'vegetables',
items: [
{
id: 1,
name: 'carrot',
amount: 3,
unit: 'pc',
},
{
id: 2,
name: 'potato',
amount: 1,
unit: 'kg',
},
{
id: 3,
name: 'broccoli',
amount: 2,
unit: 'pc',
},
],
},
{
category: 'fruits',
items: [
{
id: 4,
name: 'orange',
amount: 4,
unit: 'pc',
},
{
id: 5,
name: 'blueberries',
amount: 250,
unit: 'g',
},
],
},
{
category: 'drinks',
items: [
{
id: 6,
name: 'Coca Cola',
amount: 2,
unit: 'l',
},
{
id: 7,
name: 'Grapefruit juice',
amount: 1,
unit: 'l',
},
{
id: 8,
name: 'Water',
amount: 1,
unit: 'l',
},
],
},
{
category: 'cereal products',
items: [
{
id: 9,
name: 'Cereal',
amount: 2,
unit: 'pack',
},
{
id: 10,
name: 'Muesli',
amount: 1,
unit: 'kg',
},
],
},
];

我想删除items数组中的项，并保持其余项不变。问题出在我的reducer函数中，我的switch语句返回了错误的值：

const rootReducer = (state = initialState, action) => {
switch (action.type) {
case 'REMOVE_ITEM':
state = [
state.map((element) => element.items.filter((item) => item.id !== action.payload.id)),
];
return state;
default:
return state;
}
};

我不是要求快速解决问题，但只要一个提示，我将不胜感激。

谢谢你们，伙计们！

Answer 1

我认为你的减速器应该是这样的：

const rootReducer = (state = initialState, action) => {
switch (action.type) {
case 'REMOVE_ITEM':
return state.map(element => ({
...element,
items: element.items.filter((item) => item.id !== action.payload.id))
})
default:
return state;
}
};

Answer 2

此解决方案假定；item.id"；值在"；initialState"；范围

const rootReducer = (state = initialState, action) => {
switch (action.type) {
case 'REMOVE_ITEM':
state = state.map(element => 
Object.assign({}, element, 
{items: element.items.filter(item => item.id !== action.payload.id)}
)
);
return state;
default:
return state;
}
};