Javascript 对象作为React子对象无效(找到:具有键{username}的对象)
我开始学习React并遵循教程,当我试图上传图片时遇到了这个错误。当我按下上载按钮时,出现了这样一个错误:“对象作为React子对象无效(找到:具有键{username}的对象)。如果您想呈现子对象集合,请改用数组。”我无法再重新加载页面。 代码如下: 1.App.jsJavascript 对象作为React子对象无效(找到:具有键{username}的对象),javascript,reactjs,Javascript,Reactjs,我开始学习React并遵循教程,当我试图上传图片时遇到了这个错误。当我按下上载按钮时,出现了这样一个错误:“对象作为React子对象无效(找到:具有键{username}的对象)。如果您想呈现子对象集合,请改用数组。”我无法再重新加载页面。 代码如下: 1.App.js import React, { useEffect, useState } from "react"; import './App.css'; import Post from './Post'; impor
import React, { useEffect, useState } from "react";
import './App.css';
import Post from './Post';
import { auth, db } from "./firebase";
import Modal from '@material-ui/core/Modal';
import { makeStyles } from '@material-ui/core/styles';
import { Button, Input } from "@material-ui/core";
import ImageUpload from './ImageUpload';
function getModalStyle() {
const top = 50;
const left = 50;
return {
top: `${top}%`,
left: `${left}%`,
transform: `translate(-${top}%, -${left}%)`,
};
}
const useStyles = makeStyles((theme) => ({
paper: {
position: 'absolute',
width: 400,
backgroundColor: theme.palette.background.paper,
border: '2px solid #000',
boxShadow: theme.shadows[5],
padding: theme.spacing(2, 4, 3),
},
}));
function App() {
const classes = useStyles();
const [modalStyle] = React.useState(getModalStyle);
const [posts, setPosts] = useState([]);
const [open, setOpen] = useState(false);
const [openSignIn, setOpenSignIn] = useState('');
const [username, setUsername] = useState('');
const [email, setEmail] = useState('');
const [password, setPassword] = useState('');
const [user, setUser] = useState(null);
//UseEffect -> Run a piece of code based on a specific condition
useEffect(() => {
const unsubscribe = auth.onAuthStateChanged((authUser) => {
if (authUser) {
//user has logged in...
console.log(authUser);
setUser(authUser);
} else {
//user has logged out...
setUser(null);
}
return () => {
//perform some cleanup action
unsubscribe();
}
})
}, [user, username]);
useEffect(() => {
//this is where the code runs
db.collection('posts').onSnapshot(snapshot => {
//everytime a new post is added, this code fires...
setPosts(snapshot.docs.map(doc => ({
id: doc.id,
post: doc.data()
})));
})
}, []);
const signUp = (event) => {
event.preventDefault();
auth
.createUserWithEmailAndPassword(email, password)
.then((authUser) => {
return authUser.user.updateProfile({
displayName: username
})
})
.catch((error) => alert(error.message))
}
const signIn = (event) => {
event.preventDefault();
auth
.signInWithEmailAndPassword(email, password)
.catch((error) => alert(error.message))
setOpenSignIn(false);
}
return (
<div className="app">
{user?.displayName ? (
<ImageUpload username={user.displayName} />
) : (
<h3>Sorry you need to login to upload</h3>
)}
<Modal
open={open}
onClose={() => setOpen(false)}
>
<div style={modalStyle} className={classes.paper}>
<form className="app__signup">
<center>
<img
className="app__headerImage"
src="https://www.instagram.com/static/images/web/mobile_nav_type_logo.png/735145cfe0a4.png"
alt=""
/>
</center>
<Input
placeholder="username"
type="text"
value={username}
onChange={(e) => setUsername(e.target.value)}
/>
<Input
placeholder="email"
type="text"
value={email}
onChange={(e) => setEmail(e.target.value)}
/>
<Input
placeholder="password"
type="password"
value={password}
onChange={(e) => setPassword(e.target.value)}
/>
<Button type="submit" onClick={signUp}>Sign Up</Button>
</form>
</div>
</Modal>
<Modal
open={openSignIn}
onClose={() => setOpenSignIn(false)}
>
<div style={modalStyle} className={classes.paper}>
<form className="app__signup">
<center>
<img
className="app__headerImage"
src="https://www.instagram.com/static/images/web/mobile_nav_type_logo.png/735145cfe0a4.png"
alt=""
/>
</center>
<Input
placeholder="email"
type="text"
value={email}
onChange={(e) => setEmail(e.target.value)}
/>
<Input
placeholder="password"
type="password"
value={password}
onChange={(e) => setPassword(e.target.value)}
/>
<Button type="submit" onClick={signIn}>Sign In</Button>
</form>
</div>
</Modal>
<div className="app__header">
<img
className="app__headerImage"
src="https://www.instagram.com/static/images/web/mobile_nav_type_logo.png/735145cfe0a4.png"
alt="" />
</div>
{user ? (
<Button onClick={() => auth.signOut()}>Logout</Button>
) : (
<div className="app__loginContainer">
{/* : is stand for OR */}
<Button onClick={() => setOpenSignIn(true)}>Sign In</Button>
<Button onClick={() => setOpen(true)}>Sign Up</Button>
</div>
)}
<h1>Hello Joes! Let's build an Instagram CLone with React</h1>
{
posts.map(({ id, post }) => (
<Post key={id} username={post.username} caption={post.caption} imgUrl={post.imgUrl} />
))
}
</div>
);
}
export default App;
import React,{useffect,useState}来自“React”;
导入“/App.css”;
从“./Post”导入Post;
从“/firebase”导入{auth,db}”;
从“@material ui/core/Modal”导入模态;
从'@material ui/core/styles'导入{makeStyles};
从“@material ui/core”导入{按钮,输入};
从“/ImageUpload”导入ImageUpload;
函数getModalStyle(){
常数top=50;
常数左=50;
返回{
top:`${top}%`,
左:`${left}%`,
transform:`translate(${top}%,-${left}%)`,
};
}
const useStyles=makeStyles((主题)=>({
论文:{
位置:'绝对',
宽度:400,
背景色:theme.palete.background.paper,
边框:“2px实心#000”,
boxShadow:theme.shadows[5],
填充:主题。间距(2,4,3),
},
}));
函数App(){
const classes=useStyles();
常量[modalStyle]=React.useState(getModalStyle);
const[posts,setPosts]=useState([]);
const[open,setOpen]=useState(false);
常量[openSignIn,setOpenSignIn]=useState(“”);
const[username,setUsername]=useState(“”);
const[email,setEmail]=useState(“”);
const[password,setPassword]=useState(“”);
const[user,setUser]=useState(null);
//useffect->根据特定条件运行一段代码
useffect(()=>{
const unsubscribe=auth.onAuthStateChanged((authUser)=>{
if(authUser){
//用户已登录。。。
console.log(authUser);
setUser(authUser);
}否则{
//用户已注销。。。
setUser(空);
}
return()=>{
//执行一些清理操作
取消订阅();
}
})
},[用户,用户名];
useffect(()=>{
//这就是代码运行的地方
db.collection('posts').onSnapshot(快照=>{
//每次添加新帖子时,此代码都会触发。。。
setPosts(snapshot.docs.map(doc=>({
id:doc.id,
post:doc.data()
})));
})
}, []);
常量注册=(事件)=>{
event.preventDefault();
认证
.createUserWithEmailAndPassword(电子邮件,密码)
。然后((authUser)=>{
返回authUser.user.updateProfile({
显示名称:用户名
})
})
.catch((错误)=>警报(错误消息))
}
常量符号=(事件)=>{
event.preventDefault();
认证
.使用电子邮件和密码登录(电子邮件、密码)
.catch((错误)=>警报(错误消息))
setOpenSignIn(假);
}
返回(
{user?.displayName(
) : (
抱歉,您需要登录才能上载
)}
setOpen(false)}
>
setUsername(e.target.value)}
/>
setEmail(e.target.value)}
/>
setPassword(e.target.value)}
/>
注册
setOpenSignIn(假)}
>
setEmail(e.target.value)}
/>
setPassword(e.target.value)}
/>
登录
{用户(
auth.signOut()}>注销
) : (
{/*:表示或*/}
setOpenSignIn(true)}>登录
setOpen(true)}>注册
)}
你好,Joes!让我们用React创建Instagram克隆
{
map({id,post})=>(
))
}
);
}
导出默认应用程序;
这是ImageUpload文件
2.ImageUpload.js
从'@material ui/core'导入{Button}
从“React”导入React,{useState};
从'./firebase'导入{storage,db};
从“firebase”导入firebase;
函数ImageUpload(用户名){
const[image,setImage]=useState(null);
const[progress,setProgress]=useState(0);
const[caption,setCaption]=useState(“”);
常数handleChange=(e)=>{
if(e.target.files[0]){
setImage(e.target.files[0]);
}
};
常量handleUpload=()=>{
const uploadTask=storage.ref(`images/${image.name}`).put(image);
上传任务(
“状态改变”,
(快照)=>{
//进步功能。。。
const progress=Math.round(
(snapshot.bytesttransfered/snapshot.totalBytes)*100
);
设定进度(进度);
},
(错误)=>{
//错误函数。。。
console.log(错误);
警报(错误消息);
},
() => {
//完整功能。。。
存储
.ref(“图像”)
.child(image.name)
.getDownloadURL()
。然后(url=>{
//在数据库上发布图像
db.收集(“帖子”)。添加({
时间戳:firebase.firestore.FieldValue.serverTimestamp(),
描述:描述,
imageUrl:url,
用户名:username
});
setProgress(0);
设置标题(“”);
setImage(空);
});
}
);
};
返回(
{/*我想要…*/}
{/*标题输入*/}
{/*文件选择器*/}
{/*发布按钮*/}
<progress value={progress} max="100" />
<Progress value={progress} max="100" />