所以我基本上开始学习Redux,并希望创建一个简单的商店应用程序,您可以将手机添加到购物车。我创建了一个状态对象,在其中,我创建了一个包含对象的数组,其中包含商店中的项目列表。我想更新[+]点击订购的商品数量,但现在不起作用。我一直在努力争取1小时,但仍然没有看到问题出在哪里。
Reducer看起来像那样:
const initialState = {
liked:0,
cart:0,
item: [
{
id:1,
name: 'Iphone 8',
price: 2000,
desc: 'The new Iphone 8 available at our store!',
orderedNum: 0
},
{
id:2,
name: 'Iphone 6',
price: 1500,
desc: 'The new Iphone 6 available at our store!',
orderedNum: 0
},
{
id:3,
name: 'Samsung S8',
price: 2200,
desc: 'The new Samsung S8 available at our store!',
orderedNum: 0
},
{
id:4,
name: 'Xiaomi Mi 6',
price: 1400,
desc: 'The new Xiaomi Mi 6 available at our store!',
orderedNum: 0
},
{
id:5,
name: 'Pocophone P1',
price: 2100,
desc: 'The new Pocophone P1 available at our store!',
orderedNum: 0
},
{
id:6,
name: 'Nokia 3310',
price: 999,
desc: 'The new Nokia 3310 available at our store!',
orderedNum: 0
},
]
}
const reducer = (state = initialState, action) => {
const newState = {...state};
switch(action.type) {
case 'ADD_NUM':
return state.item.map((el, index) => {
if(el.id === action.id ){
return {
...el,
orderedNum: el.orderedNum + 1
}
}
return el;
})
default:
break;
}
return newState;
}
export default reducer;
const mapStateToProps = state => {
return {
item: state.item
}
}
const mapDispatchToProps = dispatch => {
return {
addNum: () => dispatch ({
type: 'ADD_NUM',
id: this.props.id,
value: 1
})
}
我以不同的方式尝试过它,但我相信它可能是在reducer中嵌套的问题。
有人建议吗?
让我们从您的减速机开始
const reducer = (state = initialState, action) => {
switch (action.type) {
case "ADD_NUM":
return {
// destruct and return a new object otherwise react wont update the UI
...state,
item: state.item.map(el =>
el.id === action.id
? { ...el , orderedNum: el.orderedNum + action.value }
: el
)
};
default:
return state;
}
};
mapDispatchToProps
const mapDispatchToProps = dispatch => {
return {
// add id to addNum
addNum: id =>
dispatch({
type: "ADD_NUM",
id,
value: 1
})
};
};
项目组件
const Items = ({ item, addNum }) => (
item.map(el => (
<div key={el.id}>
<h1>{el.name}</h1>
<h3>{el.price}</h3>
<h3>{`orderedNum: ${el.orderedNum}`}</h3>
// add the id to addNum
<button onClick={() => addNum(el.id)}>+</button>
</div>
))
);
你的减速机应该是这样的:
export default (state = initialState, action) => {
switch (action.type) {
case 'ADD_ITEM':
return [...state, action.item];
case 'REMOVE_ITEM':
return state.filter(({ id }) => id !== action.id);
default:
return state;
}
};
正如在评论中指出的那样,上面的函数适用于一个初始状态,它是一个数组而不是一个对象......如果它是一个对象,那么如何处理它(使用来自lodash mapKeys
和omit
的两个辅助方法:
export default (state = {}, action) => {
switch (action.type) {
case FETCH_ITEMS:
return { ...state, ...mapKeys(action.payload, 'id') };
case FETCH_ITEM:
return { ...state, [action.payload.id]: action.payload };
case CREATE_ITEM:
return { ...state, [action.payload.id]: action.payload };
case EDIT_ITEM:
return { ...state, [action.payload.id]: action.payload };
case DELETE_ITEM:
return omit(state, action.payload);
default:
return state;
}
};