有一个令人沮丧的问题,希望有人能帮助。全面回购可在https://github.com/georgecook92/Stir/blob/master/src/components/posts/viewPosts.jsx。
直接进入代码-
componentDidMount() {
const {user_id,token} = this.props.auth;
this.props.startLoading();
console.log('props auth', this.props.auth);
if (user_id) {
console.log('user_id didMount', user_id);
this.props.getUserPosts(user_id, token);
}
}
如果组件是通过ui从另一个组件加载的,那么它将按预期运行。但是,如果页面被刷新,user_id等不能立即用于componentDidMount。
我已经检查过了,它是可用的以后,但我发现,如果我移动我的AJAX调用得到的帖子到一个渲染方法或其他生命周期的方法,如componentWillReceiveProps -道具正在不断更新,它锁定的UI -不理想。
我也不确定为什么每秒多个ajax调用正在进行,如果我将ajax调用移动到渲染方法。
我希望你能帮忙!谢谢你。
编辑。
export function getUserPosts(user_id, token){
return function(dispatch) {
if (window.indexedDB) {
var db = new Dexie('Stir');
db.version(1).stores({
posts: '_id, title, user_id, text, offline',
users: 'user_id, email, firstName, lastName, token'
});
// Open the database
db.open().catch(function(error) {
alert('Uh oh : ' + error);
});
db.posts.toArray().then( (posts) => {
console.log('posts:', posts);
if (posts.length > 0) {
dispatch( {type: GET_POSTS, payload: posts} );
}
});
}
axios.get(`${ROOT_URL}/getPosts?user_id=${user_id}`, {
headers: {
authorisation: localStorage.getItem('token')
}
}).then( (response) => {
console.log('response from getPosts action ', response);
dispatch( {type: GET_POSTS, payload: response.data} );
dispatch(endLoading());
response.data.forEach( (post) => {
if (post.offline) {
if (window.indexedDB) {
db.posts.get(post._id).then( (result) => {
if (result) {
//console.log('Post is already in db', post.title);
} else {
//console.log('Post not in db', post.title);
//useful if a posts offline status has changed
db.posts.add({
_id: post._id,
title: post.title,
user_id: post.user_id,
text: post.text,
offline: post.offline
});
}
} )
}
}
} );
})
.catch( (err) => {
console.log('error from get posts action', err);
if (err.response.status === 503) {
dispatch(endLoading());
dispatch(authError('No internet connection, but you can view your offline posts! '));
} else {
dispatch(endLoading());
dispatch(authError(err.response.data.error));
}
});
}
}
我建议使用componentWillReceiveProps
并将你的道具保存为状态,以便在发生变化时触发重新渲染(例如,道具从未定义变为具有值)。像这样可以工作:
import React, {Component} from 'react';
// using lodash for checking equality of objects
import _isEqual from 'lodash/isEqual';
class MyComponent extends Component {
constructor(props={}) {
super();
this.state = props;
}
// when the component receives new props, like from an ajax request,
// check to see if its different from what we have. If it is then
// set state and re-render
componentWillReceiveProps(nextProps) {
if(!_isEqual(nextProps, this.state)){
this.setState(nextProps);
}
}
render() {
return (
<div>{this.state.ItemPassedAsProp}</div>
);
}
}