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[英]React / Redux: mapStateToProps not actually mapping state to props
[英]React redux mapStateToProps not set return to my props
使用 prop 时出现问题,它从null
开始,然后我使用map
但因为它是null
返回错误。
然后最终没有响应更新的状态:
class HomeProducts extends Component {
componentDidMount() {
this.props.fetchProduct();
}
render() {
console.log(this.props)
const productItems = this.props.products.map( product => (
<div className="col-md-4 pt-4 pl-2">
<div className = "thumbnail text-center">
<a href={`#${product.id}`} onClick={(e)=>this.props.handleAddToCard(e,product)}>
<p>
{product.name}
</p>
</a>
</div>
<b>{util.formatCurrency(product.price)}</b>
<button className="btn btn-primary" onClick={(e)=>this.props.handleAddToCard(e,product)}>Add to Cart</button>
</div>
)
)
return (
<div className="container">
<div className="row">
</div>
</div>
)
}
}
const mapStateToProps = (state) => {
console.log(state);
return{
products: state.data.products,
loading: state.data.loading,
error: state.data.error
}
};
const mapActionsToProps = {
fetchProduct: fetchProduct
};
export default connect(mapStateToProps, mapActionsToProps)(HomeProducts);
我的减速机:
import {
FETCH_SUCESS,
FETCH_FAIL,
FETCH_LOADING,
} from '../constants/fetchTypes';
const initialState = {
loading: false,
products: [],
error: null
};
export default function productReducer(state = initialState, action) {
switch (action.type) {
case FETCH_LOADING:
return {
...state,
loading: true
};
case FETCH_SUCESS:
return {
...state,
loading: false,
error: null,
...state, products: action.data
};
case FETCH_FAIL:
return {
...state,
loading: false,
error: action.error
};
default:
return state;
}
}
我的行动:
import api from '../../services/api';
import {FETCH_SUCESS,FETCH_FAIL,FETCH_LOADING} from '../constants/fetchTypes';
const fetchSucess = data => ({
type: FETCH_SUCESS,
data
});
const fetchStarted = () => ({
type: FETCH_LOADING
});
const fetchFailed = error => ({
type: FETCH_FAIL,
error
});
export const fetchProduct = () => {
console.log('action')
return dispatch => {
dispatch(fetchStarted());
api
.get('/products')
.then(res => {
dispatch(fetchSucess(res.data));
})
.catch(err => {
dispatch(fetchFailed(err.message));
});
};
};
我的合路器减速器:
import { combineReducers } from 'redux'
import productReducer from './productsFetch.reducer';
export default combineReducers({
data: productReducer
});
我的店铺:
export default function configureStore(initialState) {
return createStore(
rootReducer,
initialState,
applyMiddleware(thunk)
);
}
我得到了:
无法读取未定义的属性“地图”
你能在不使用 createStore 中的 initialState 的情况下尝试这样吗?
return createStore(
rootReducer,
applyMiddleware(thunk)
);
似乎当我们尝试在 createStore 和 reducer 中初始化状态时,某些东西被破坏了。
看来您需要检查您的减速器中的initialState
,看看您是否真的有一个用于products
的空数组。 这样您就不必处理在第一次加载时为空的情况。 因此,当使用[]
的 initialState 时,您还可以为用户处理不同的消息,例如(如果数组为空,则显示 LOADING(对于您还在减速器中处理该状态的情况)或 EMPTY 列表,当你实际上完成了数据的加载。
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