Question 118953 in Firebase Question posted in
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Firebase – Typescript: Property 'size' does not exist on type 'never'

I don’t understand why I’m getting this error for the code below.

Typescript: Property ‘size’ does not exist on type ‘never’

The error is pointing to friendRef.size.

It is also giving an error on friendRef.update:

Property ‘update’ does not exist on type ‘never’

How do I properly run a WHERE clause query on a collection that will only ever return either 1 or 0 records and then update some of its properties?

export const onRespondedToFriendRequest = functions.firestore
  .document("users/{userDocID}/notifications/{notifID}")
  .onUpdate(async (change, context) => {
    const notifID = context.params.notifID;
    const uid = context.params.userDocID; // user A
    const beforeData = change.before.data();
    const afterData = change.after.data();
    const friendUID = afterData.uid; // user B (the friend)

    // If notifID is "2" and moveOnToNextStep = true
    if (notifID === "2" && afterData.moveOnToNextStep) {
      const friendsQuerySnapshot = await fs
        .collection("users/" + friendUID + "/friends")
        .where("uid", "==", uid)
        .limit(1)
        .get();

      let friendRef;

      friendsQuerySnapshot.forEach((friendDoc) => {
        friendRef = friendDoc.ref;        
      });

      if (friendRef && friendRef.size !== 0) { // ERROR HERE
        
        await friendRef.update({ // ERROR HERE
          stat: "1",
          modifiedDate: Math.floor((new Date).getTime()/1000).toString(),
        });
      }
    }
  });
Tags:

2

Answers


  1. 0

    set type for friendRef:

    let friendRef: Parameters<typeof friendsQuerySnapshot.forEach>[0]
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  2. 0

    Your code doesn’t handle the case where there are no results. In that case friendRef will be undefined (its default value), and you can’t call size or update on that.

    The simplest fix is to check for an empty result first, and only then have the rest of your code:

    const friendsQuerySnapshot = await fs
  .collection("users/" + friendUID + "/friends")
  .where("uid", "==", uid)
  .limit(1)
  .get();

if (!friendsQuerySnapshot.empty) {
  let friendRef;

  friendsQuerySnapshot.forEach((friendDoc) => {
    friendRef = friendDoc.ref;        
  });

  if (friendRef) {
    await friendRef.update({
      stat: "1",
      modifiedDate: Math.floor((new Date).getTime()/1000).toString(),
    });
  }
}

    At this point you actually also don’t need the loop anymore, and can just do:

    const friendsQuerySnapshot = await fs
  .collection("users/" + friendUID + "/friends")
  .where("uid", "==", uid)
  .limit(1)
  .get();

if (!friendsQuerySnapshot.empty) {
  const friendRef = friendsQuerySnapshot.docs[0].ref;

  await friendRef.update({
    stat: "1",
    modifiedDate: Math.floor((new Date).getTime()/1000).toString(),
  });
}
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