每次获取数据时如何创建新元素并渲染数据 [英] How to create new element and render data each time the data is fetched in react
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问题描述
我是新来的反应者,我需要渲染并列出从firebase提取的数据到我尝试执行的html,
I am new to react and I need to render and list data fetched from firebase to the html I tried doing this,
const Music = ({ match }) => {
const [title, setTitle] = useState(null)
const [user, setUser] = useState(null)
const [pfp, setPfp] = useState(null)
const { params: { uID } } = match;
useEffect(()=>{ firebase.database().ref("users/"+uID+"/public/songs/").on("value", (snapshot)=>{
var musics = snapshot.val()
Object.values(musics).forEach((value)=>{
//I need to render this title each and create new li
setTitle(<li>{value.title}</li>)
})
})
}, [])
return(
<>
<Nav />
<div id = "profile" className = "main">
<div class = "profile-container">
<div className = "cover-pic">
<img src = "" />
<div className = "pfp">
<img src = {pfp} height = "100" width = "100"/>
</div>
<div className = "User-Name">
<h1>{user}</h1>
</div>
</div>
<div class = "tabsContainer">
<div class = "tabs-holder">
<NavLink to = {"/u/"+uID+"/music"}><button><span>Music</span></button></NavLink>
<button><span>Playlist</span></button>
<button><span>About</span></button>
</div>
</div>
</div>
<div class = "music-content-container">
<div class = "music-box">
<div class = "user-musics">
<ul>
//the title should rendered over here
{title}
</ul>
</div>
</div>
</div>
</div>
<Header />
)
}
但它仅呈现一个元素.虽然我的数据库中有5个元素.如何解决/做到这一点?如何使程序创建所有5个
but it only renders one element. While there are 5 elements in my database. How to fix/ do this? how to make the program create all 5
推荐答案
不要在useEffect中渲染东西,只需使用它来添加逻辑并设置状态:
Don't rendere stuff in useEffect, just use it to add logic and set state:
const Music = ({ match }) => {
const [musics, setMusics] = useState([])
const [user, setUser] = useState(null)
const [pfp, setPfp] = useState(null)
const { params: { uID } } = match;
useEffect(()=>{
firebase.database()
.ref("users/"+uID+"/public/songs/")
.on("value", (snapshot)=>{
var musics = snapshot.val()
//not sure how music obj is , just set it as an array of something
setMusics(musics)
})
}, [])
return(
<>
<Nav />
<div id = "profile" className = "main">
<div class = "profile-container">
<div className = "cover-pic">
<img src = "" />
<div className = "pfp">
<img src = {pfp} height = "100" width = "100"/>
</div>
<div className = "User-Name">
<h1>{user}</h1>
</div>
</div>
<div class = "tabsContainer">
<div class = "tabs-holder">
<NavLink to = {"/u/"+uID+"/music"}><button><span>Music</span></button></NavLink>
<button><span>Playlist</span></button>
<button><span>About</span></button>
</div>
</div>
</div>
{musics &&
<div class = "music-content-container">
<div class = "music-box">
<div class = "user-musics">
<ul>
{musics.map((el,key)=><li>{el.title}</li>) }}
</ul>
</div>
</div>
</div>}
</div>
<Header />
)
}
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