I am getting an error on my .map function. I believe the issue is greater than that though because sometimes my fetch comes back as undefined. I have been looking into solutions but haven't found anything that has given me a solution.

Props - is a logged-in user object that has the users ID

discBag consoles as an array sometimes but also will console as undefined. This is where I believe my issue is happening. I have looked into component mounting, but I was confused with the class and super() syntax.

here is the error I am getting along with the two console.logs

I am new to web development and this is my very first stack overflow question. Any solutions or guidance to the solution is greatly appreciated!

function DiscBag(props) {
  const [loading, setLoading] = useState(true);
  const [discBag, setDiscBag] = useState([]);

  const userID = props.user.user.id;
console.log(userID)
console.log(discBag)

  const getDiscs = async () => {
    try {
      const response = await fetch(`/users/${userID}`)
      const data = await response.json()
      
      setLoading(false)
      setDiscBag(data.discBag)

    } catch (error) {
      console.log(error)
    }


  };
  useEffect(() => {

    getDiscs();
  }, []);

  if (loading) {
    return <div> ....loading bro</div>;
  }
  return (
    <div className="child">
      <p>not loading</p>
      {discBag.map((index, discs) => (
        <div className="discs" key={index}>
          {discs}
        </div>
      ))}
    </div>
  );
}

CodePudding user response：

According to your description, it seems that there are times that the call to your server does not return a data.discBag value, which causes the discBag state to be empty (and the map function can only run on arrays, here is the fix for the problem:

{discBag?.map((discs, index) => (

CodePudding user response：

Can you try with {discBag.map((discs, index) => ... ? first one is element, second one is the index like below;

array.map((currentElement, index) => { something... })