在我的商店中,我有一个具有此形状的状态:{posts: [{...},{...}]}
,但是当我在Home.js中使用mapStateToProps()
时,状态返回{posts: []}
,其中包含一个空数组(其中有曾经是商店州的一个数组)。
我是否错误地使用mapStateToProps()
或问题是否源于Redux循环的其他部分?
API提取我暂时使用,位于actions.js
// api
const API = "http://localhost:3001"
let token = localStorage.token
if (!token) {
token = localStorage.token = Math.random().toString(36).substr(-8)
}
const headers = {
'Accept': 'application/json',
'Authorization': token
}
// gets all posts
const getAllPosts = token => (
fetch(`${API}/posts`, { method: 'GET', headers })
);
动作和动作创建者,使用thunk中间件:
// actions.js
export const REQUEST_POSTS = 'REQUEST_POSTS';
function requestPosts (posts) {
return {
type: REQUEST_POSTS,
posts
}
}
export const RECEIVE_POSTS = 'RECEIVE_POSTS';
function receivePosts (posts) {
return {
type: RECEIVE_POSTS,
posts,
receivedAt: Date.now()
}
}
// thunk middleware action creator, intervenes in the above function
export function fetchPosts (posts) {
return function (dispatch) {
dispatch(requestPosts(posts))
return getAllPosts()
.then(
res => res.json(),
error => console.log('An error occured.', error)
)
.then(posts =>
dispatch(receivePosts(posts))
)
}
}
减速机:
// rootReducer.js
function posts (state = [], action) {
const { posts } = action
switch(action.type) {
case RECEIVE_POSTS :
return posts;
default :
return state;
}
}
临时包含Redux存储的根组件:
// index.js (contains store)
const store = createStore(
rootReducer,
composeEnhancers(
applyMiddleware(
logger, // logs actions
thunk // lets us dispatch() functions
)
)
)
store
.dispatch(fetchPosts())
.then(() => console.log('On store dispatch: ', store.getState())) // returns expected
ReactDOM.render(
<BrowserRouter>
<Provider store={store}>
<Quoted />
</Provider>
</BrowserRouter>, document.getElementById('root'));
registerServiceWorker();
主要组成部分:
// Home.js
function mapStateToProps(state) {
return {
posts: state
}
}
export default connect(mapStateToProps)(Home)
在Home.js组件中,console.log('Props', this.props)
返回{posts:[]},我希望{posts:[{...},{...}}}。
***编辑:
在发送之前和reducer中的操作中添加console.log()
之后,这是控制台输出:
Console output link (not high enough rep to embed yet)
答案 0 :(得分:2)
redux存储应该是一个对象,但似乎它在根reducer中被初始化为一个数组。您可以尝试以下方法:
const initialState = {
posts: []
}
function posts (state = initialState, action) {
switch(action.type) {
case RECEIVE_POSTS :
return Object.assign({}, state, {posts: action.posts})
default :
return state;
}
}
然后在mapStateToProps函数中:
function mapStateToProps(state) {
return {
posts: state.posts
}
}