Redux async action triggered after request finished. Why? - react-redux

Question

I have problem with my async action. I would like to set 'loading' state to true when action fetchPosts() is called and 'loading' state to false when action fetchPostsSuccess() or fetchPostsFailiure().
With my current code it works almost fine except 'loading' state change when fetchPosts() receive response from server and I would like to change this state at the beginning of request.
Here is simple code which shows my steps.
I'm using axios and redux-promise (https://github.com/acdlite/redux-promise).
// actions
export function fetchPosts() {
const request = axios.get(`${API_URL}/posts/`);
return {
type: 'FETCH_POSTS',
payload: request,
};
}
export function fetchPostsSuccess(posts) {
return {
type: 'FETCH_POSTS_SUCCESS',
payload: posts,
};
}
export function fetchPostsFailure(error) {
return {
type: 'FETCH_POSTS_FAILURE',
payload: error,
};
}
// reducer
const INITIAL_STATE = {
posts: [],
loading: false,
error: null,
}
const postsReducer = (state = INITIAL_STATE, action) => {
switch (action.type) {
case 'FETCH_POSTS':
return { ...state, loading: true, error: null };
case 'FETCH_POSTS_SUCCESS':
return { ...state, posts: action.payload, loading: false };
case 'FETCH_POSTS_FAILURE':
return { ...state, posts: [], loading: false, error: action.payload };
default:
return state;
}
}
const rootReducer = combineReducers({
postsList: postsReducer,
});
// store
function configureStore(initialState) {
return createStore(
rootReducer,
applyMiddleware(
promise,
),
);
}
const store = configureStore();
// simple Posts app
class Posts extends Component {
componentWillMount() {
this.props.fetchPosts();
}
render() {
const { posts, loading } = this.props.postsList;
return (
<div>
{loading && <p>Loading...</p>}
<ul>
{posts.map(post => <li key={post.id}>{post.title}</li>)}
</ul>
</div>
);
}
}
const mapStateToProps = state => ({
postsList: state.postsList,
});
const mapDispatchToProps = dispatch => ({
fetchPosts: (params = {}) => {
dispatch(fetchPosts())
.then((response) => {
if (!response.error) {
dispatch(fetchPostsSuccess(response.payload.data));
} else {
dispatch(fetchPostsFailure(response.payload.data));
}
});
},
});
const PostsContainer = connect(mapStateToProps, mapDispatchToProps)(Posts);
// main
ReactDOM.render((
<Provider store={store}>
<Router history={browserHistory}>
<Route path="posts" component={PostsContainer} />
</Router>
</Provider>
), document.getElementById('appRoot'));
Can someone guide me what I'm doing wrong ?

Answer 1

It's turned out the problem is with 'redux-promise' package. This async middleware has no such thing like 'pending' state of promise (called 'optimistic update') .
It changes the state only when promise has been resolved or rejected.
I should use different middleware which allow for 'optimistic updates'

Answer 2

Your problem ís with redux-promise. You should use redux-thunk instead that allows you to return a function and dispatch multiple times. Have a look at it ;)!