Javascript 如何使用componentDidMount()发出多个axios.get()请求,并将响应值1分配给2?
我正在尝试用WordPressRESTAPI构建一个web应用程序 我正在向端点发出初始GET请求,并通过Javascript 如何使用componentDidMount()发出多个axios.get()请求,并将响应值1分配给2?,javascript,reactjs,rest,promise,axios,Javascript,Reactjs,Rest,Promise,Axios,我正在尝试用WordPressRESTAPI构建一个web应用程序 我正在向端点发出初始GET请求,并通过res.data解析以获取一些值。但是,其中一个值featured_media是我试图发出的第二个GET请求的参数。我发现很难在第二个get请求中从该状态获取该值 这里是美国 state = { graduatepost: {}, category: '', featured_media: '', imgURL: '',
res.data
解析以获取一些值。但是,其中一个值featured_media
是我试图发出的第二个GET请求的参数。我发现很难在第二个get请求中从该状态获取该值
这里是美国
state = {
graduatepost: {},
category: '',
featured_media: '',
imgURL: '',
isLoaded: false
}
下面是componentDidMount()
第一次获取请求:http://localhost:8000/wp-json/wp/v2/blog/${this.props.match.params.id}
第二次获取请求:http://localhost:8000/wp-json/wp/v2/media/${featured_media}
如您所见,第二个请求需要值featured\u media
,该值在第一个GET请求的响应中
我正在像这样渲染组件
render() {
const { graduatepost, category, isLoaded, featured_media, imgURL } = this.state;
if(isLoaded) {
return (
<Styles>
<Fragment>
<Link to='/graduate-posts'>Go Back</Link> // Ignore this
<hr />
<h1>{graduatepost.title.rendered}</h1>
<div dangerouslySetInnerHTML={{__html: graduatepost.content.rendered}}></div>
<h4>Category: {category}</h4>
<h4>featured_media: {featured_media}</h4>
<h4>imgURL: {imgURL}</h4>
</Fragment>
</Styles>
)
}
return <h3>Loading...</h3> // Ignore this
}
我假设这是因为featured\u media
为空/未定义,但我无法确定如何从第一个GET请求response中提取该值
这看起来似乎很明显,但我对一起使用React.js和API还比较陌生。非常感谢你的帮助
谢谢。您尝试过异步功能吗
可能在第一个axios.get的响应中请求它。它不起作用的原因是因为
this.setState
是React中的一个异步函数,因此当您访问它的正下方时,它是未定义的
尝试以下方法:
axios.get(`http://localhost:8000/wp-json/wp/v2/blog/${this.props.match.params.id}`)
.then((res) => {
const state = {
graduatepost: res.data,
category: res.data.categories[0],
featured_media: res.data.featured_media,
isLoaded: true
}
this.setState(state)
return axios.get(`http://localhost:8000/wp-json/wp/v2/media/${state.featured_media}`);
})
.then((res) => {
// do something with res
})
.catch((err) => {
// handle err
});
立即访问设置数据的最佳方法是使用。
this.setState
接受回调作为其第二个参数(setState(updater,[callback])
),因此我们应该在callback
语句中提出第二个请求。
您的代码应该是这样的:
axios
.得到(`http://localhost:8000/wp-json/wp/v2/blog/${this.props.match.params.id}`)
。然后((res)=>
这是我的国家(
{
研究生职位:研究数据,
类别:res.data.categories[0],
特色媒体:res.data.featured\u媒体,
isLoaded:是的,
},
() =>
axios
.得到(
`http://localhost:8000/wp-json/wp/v2/media/${this.state.featured_media}`
)
。然后((res)=>{
这是我的国家({
imgURL:res[0]。data.media\u details.size.full.source\u url,
isLoaded:是的,
})
})
)
)
.catch((err)=>console.log(err))
我准备了一个示例,其中显示了所有用户,如果单击查看帖子按钮,它将显示该用户的所有帖子
App.js
class App extends React.Component {
render() {
return (
<Router>
<div>
<ul>
<li>
<Link to="/">Home</Link>
</li>
<li>
<Link to="/posts">Posts</Link>
</li>
</ul>
<hr/>
<Switch>
<Route exact path="/">
<UserList/>
</Route>
<Route path="/posts">
<PostListPageByUser/>
</Route>
</Switch>
</div>
</Router>
);
}
}
export default App;
类应用程序扩展了React.Component{
render(){
返回(
-
家
-
帖子
);
}
}
导出默认应用程序;
用户列表组件
import React from 'react';
import axios from 'axios';
import PostListPageByUser from "./PostListPageByUser";
import {withRouter} from "react-router-dom";
class UserList extends React.Component {
state = {
users: [],
showPostList: false,
user: {}
};
componentDidMount() {
axios.get(`https://jsonplaceholder.typicode.com/users`)
.then(res => {
const users = res.data;
console.log(users);
this.setState({users});
})
}
handleClick = (user) => {
console.log(user);
this.setState({showPostList: true, user: user});
this.props.history.push({
pathname: '/posts',
user: user
});
};
render() {
return (
<div>
<ul>
{this.state.users ? this.state.users.map(user => <div key={user.id}>
<span style={{minWidth: 400}}>{user.name} </span>
<button onClick={() => {
this.handleClick(user)
}}>See Posts
</button>
</div>) : null}
</ul>
{this.state.showPostList ? <PostListPageByUser user={this.state.user}/> : null}
</div>
)
}
}
export default withRouter(UserList);
import React from "react";
import axios from 'axios';
import {withRouter} from "react-router-dom";
class PostListPageByUser extends React.Component {
signal = axios.CancelToken.source();
state = {
posts: [],
};
componentDidMount() {
if(!this.props.location.user){
alert('Please click see posts button');
this.props.history.push('/');
return;
}
axios.get(`https://jsonplaceholder.typicode.com/posts?userId=${this.props.location.user.id}`, {
cancelToken: this.signal.token,
})
.then(res => {
this.setState({posts: res.data});
console.log(res.data, 'Posts');
}).catch(err => {
console.log(err);
});
}
render() {
return (
<div>
<ul>
{
this.state.posts ? this.state.posts.map(post => <li key={post.id}>{post.title}</li>) : null
}
</ul>
</div>
)
}
}
export default withRouter(PostListPageByUser);
从“React”导入React;
从“axios”导入axios;
从“/PostListPageByUser”导入PostListPageByUser;
从“react router dom”导入{withRouter};
类UserList扩展了React.Component{
状态={
用户:[],
showPostList:false,
用户:{}
};
componentDidMount(){
axios.get(`https://jsonplaceholder.typicode.com/users`)
。然后(res=>{
const users=res.data;
console.log(用户);
this.setState({users});
})
}
handleClick=(用户)=>{
console.log(用户);
this.setState({showPostList:true,user:user});
这个。道具。历史。推({
路径名:'/posts',
用户:用户
});
};
render(){
返回(
{this.state.users?this.state.users.map(user=>
{user.name}
{
this.handleClick(用户)
}}>见帖子
):null}
{this.state.showPostList?:null}
)
}
}
使用路由器导出默认值(用户列表);
PostListByUser组件
import React from 'react';
import axios from 'axios';
import PostListPageByUser from "./PostListPageByUser";
import {withRouter} from "react-router-dom";
class UserList extends React.Component {
state = {
users: [],
showPostList: false,
user: {}
};
componentDidMount() {
axios.get(`https://jsonplaceholder.typicode.com/users`)
.then(res => {
const users = res.data;
console.log(users);
this.setState({users});
})
}
handleClick = (user) => {
console.log(user);
this.setState({showPostList: true, user: user});
this.props.history.push({
pathname: '/posts',
user: user
});
};
render() {
return (
<div>
<ul>
{this.state.users ? this.state.users.map(user => <div key={user.id}>
<span style={{minWidth: 400}}>{user.name} </span>
<button onClick={() => {
this.handleClick(user)
}}>See Posts
</button>
</div>) : null}
</ul>
{this.state.showPostList ? <PostListPageByUser user={this.state.user}/> : null}
</div>
)
}
}
export default withRouter(UserList);
import React from "react";
import axios from 'axios';
import {withRouter} from "react-router-dom";
class PostListPageByUser extends React.Component {
signal = axios.CancelToken.source();
state = {
posts: [],
};
componentDidMount() {
if(!this.props.location.user){
alert('Please click see posts button');
this.props.history.push('/');
return;
}
axios.get(`https://jsonplaceholder.typicode.com/posts?userId=${this.props.location.user.id}`, {
cancelToken: this.signal.token,
})
.then(res => {
this.setState({posts: res.data});
console.log(res.data, 'Posts');
}).catch(err => {
console.log(err);
});
}
render() {
return (
<div>
<ul>
{
this.state.posts ? this.state.posts.map(post => <li key={post.id}>{post.title}</li>) : null
}
</ul>
</div>
)
}
}
export default withRouter(PostListPageByUser);
从“React”导入React;
从“axios”导入axios;
从“react router dom”导入{withRouter};
类PostListPageByUser扩展React.Component{
signal=axios.CancelToken.source();
状态={
员额:[],
};
componentDidMount(){
如果(!this.props.location.user){
警报(“请点击查看帖子按钮”);
this.props.history.push('/');
返回;
}
axios.get(`https://jsonplaceholder.typicode.com/posts?userId=${this.props.location.user.id}`{
cancelToken:this.signal.token,
})
。然后(res=>{
this.setState({posts:res.data});
console.log(res.data,“Posts”);
}).catch(错误=>{
控制台日志(err);
});
}
render(){
返回(
{
this.state.posts?this.state.posts.map(post=>- {post.title}
):null
}
)
}
}
使用路由器导出默认值(PostListPageByUser);
这是否回答了您的问题?
import React from "react";
import axios from 'axios';
import {withRouter} from "react-router-dom";
class PostListPageByUser extends React.Component {
signal = axios.CancelToken.source();
state = {
posts: [],
};
componentDidMount() {
if(!this.props.location.user){
alert('Please click see posts button');
this.props.history.push('/');
return;
}
axios.get(`https://jsonplaceholder.typicode.com/posts?userId=${this.props.location.user.id}`, {
cancelToken: this.signal.token,
})
.then(res => {
this.setState({posts: res.data});
console.log(res.data, 'Posts');
}).catch(err => {
console.log(err);
});
}
render() {
return (
<div>
<ul>
{
this.state.posts ? this.state.posts.map(post => <li key={post.id}>{post.title}</li>) : null
}
</ul>
</div>
)
}
}
export default withRouter(PostListPageByUser);