[英]how to update state with reducer, when my state is an array not an object
我在 reducer 函數中返回新狀態時遇到問題。 我的狀態是一組對象。 每個對象都有兩個鍵值對類別: ''和項目: [{}, {}, {}] 。
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',
},
],
},
];
我想刪除 items 數組中的項目,其余部分保持不變。 問題出在我的 reducer 函數中,而我的 switch 語句返回了錯誤的值:
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;
}
};
我不是要求快速修復,但只是一個提示將不勝感激。
謝謝你們!
此解決方案假定“item.id”值在“initialState”范圍內是唯一的。
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;
}
};
我認為你的減速器應該是這樣的:
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;
}
};
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