Count unread messages using firebase and react js-CodePudding

Im building a web chat app using next js and firebase.How can i implement an unread message counter?Im using a boolean field called read inside my message doc to check if a message is read or not.

I tried using useEffect but it seems that my counter is just increasing without stoping.

const [notification,SetNotification]=useState(0)
const[messages,SetMessages]=useState([])

useEffect(()=>{
const getMessages=async ()=>{
    const data=await getDocs(lastMessageRef)
    SetMessages(data.docs.map((doc)=>({...doc.data(), id:doc.id})))
    
};
getMessages();
messages.forEach((message)=>{
    if(message.read==false){
        SetNotification(notification 1)
    }
})
},[messages])
console.log(notification)

CodePudding user response：

Split your code into two separate useEffects. Also, using SetNotifaction inside a loop will cause a lot of problems. I suggest using Array.filter instead.

const [notification,SetNotification] = useState(0)
const [messages,SetMessages] = useState([])

useEffect(() => {
  const getMessages = async () => {
    const data = await getDocs(lastMessageRef)
    SetMessages(data.docs.map((doc) => ({...doc.data(), id:doc.id}))) 
  };
  getMessages();
}, [messages]);

useEffect(() => {
  const unreadMessages = messages.filter(message => message.read === false)
  
  SetNotification(unreadMessages.length)

}, [messages]);