我在一个带有React和Redux的项目中工作,我很新,所以我试图更好地了解如何一起使用Redux-thunk和Redux-Promise。在下面,您可以看到我的文件,在我的操作中,我创建了一个获取通用函数apifetch(),以便每次需要获取时使用。此函数返回承诺,我将在loadBooks()中解决,代码正在工作并且记录上传,但是当我检查操作的日志时,我会看到第一个操作是不确定的,在有books_loading之后,load_books,books_loading和load_books_success。
我有2个问题:
1)为什么第一个操作是不确定的,而我又是Load_book而不是load_books_start?
action @ 22:54:37.403 undefined
core.js:112 prev state Object {activeBook: null, booksListing: Object}
core.js:116 action function (dispatch) {
var url = './src/data/payload.json';
dispatch(booksIsLoading(true));
return dispatch({
type: 'LOAD_BOOKS',
payload: new Promise(function (resolve) {
…
core.js:124 next state Object {activeBook: null, booksListing: Object}
action @ 22:54:37.404 BOOKS_LOADING
action @ 22:54:37.413 LOAD_BOOKS
action @ 22:54:39.420 BOOKS_LOADING
action @ 22:54:39.425 LOAD_BOOKS_SUCCESS
2)例如,如果获取的URL是错误的,我希望看到Action load_books_error,而是日志的结果:
action @ 23:06:06.837 undefined action @ 23:06:06.837 BOOKS_LOADING
action @ 23:06:06.846 LOAD_BOOKS GET
http://localhost:8000/src/data/payldoad.json 404 (Not Found) error
apiFetch Error: request failed at index.js:66 error
TypeError: Cannot read property 'json' of undefined at index.js:90
如果我不使用apifetch(),但是正常的fetch函数,所有这些都可以正常工作,也是错误的一部分,但无论如何load_books not load_books_start。
预先感谢您的任何帮助!
configurestore.js
import { createStore, applyMiddleware, compose, preloadedState } from 'redux';
import reducers from './configureReducer';
import configureMiddleware from './configureMiddleware';
const middleware = configureMiddleware();
const composeEnhancers = window.__REDUX_DEVTOOLS_EXTENSION_COMPOSE__ || compose;
const store = createStore(reducers, preloadedState, composeEnhancers(applyMiddleware(...middleware)));
export default store;
actions/index.js
import fetch from 'isomorphic-fetch';
export const booksIsLoading = (bool) => {
return {
type: 'BOOKS_LOADING',
booksLoading: bool,
};
};
const delay = ms => new Promise(resolve => setTimeout(resolve, ms));
export const apiFetch = (url) => {
const getPromise = () => (
fetch(url, {
method: 'GET',
})
.then((response) => {
if (response.status !== 200) {
throw Error('request failed');
}
return response;
})
.catch((err) => {
console.log('error apiFetch', err);
// dispatch(fetchBooksError(true));
})
);
return getPromise();
};
export const loadBooks = () => (dispatch) => {
const url = './src/data/payload.json';
dispatch(booksIsLoading(true));
return dispatch({
type: 'LOAD_BOOKS',
payload: new Promise((resolve) => {
delay(2000).then(() => {
apiFetch(`${url}`)
// fetch(`${url}`, {
// method: 'GET',
// })
.then((response) => {
resolve(response.json());
dispatch(booksIsLoading(false));
}).catch((err) => {
console.log('error', err);
});
});
}),
});
};
常数/application.js
export const LOAD_BOOKS = 'LOAD_BOOKS';
reducers/reducer_book.js
import initialState from '../model.js';
import * as types from '../constants/application';
export default function (state = initialState, action) {
switch (action.type) {
case `${types.LOAD_BOOKS}_SUCCESS`: {
console.log('reducer', action.payload);
const data = action.payload.data.items;
const items = Object.values(data);
if (items.length > 0) {
return {
...state,
books: Object.values(data),
booksFetched: true,
booksError: false,
};
}
return state;
}
case `${types.LOAD_BOOKS}_ERROR`: {
return {
...state,
booksError: true,
};
}
case 'BOOKS_LOADING':
return {
...state,
booksLoading: action.booksLoading,
};
default:
return state;
}
}
您指定了哪个顺序?
用法使操作变得不确定:
'applymiddleware(reduxpromisemiddleware(),reduxthunk)'
请将订单更改为:(首先!)
'applymiddleware(reduxthunk,reduxpromisemiddleware())'