Get array of ids from object array in firestore

Question

in firestore I have a document with two strings and also an object array with [{email: ..., id: ..., nickname: ...} {...}] I use a subscription to get all users from that specific document. The next step is to extract all ids from that object array (called "users") in a new array.. But I have no idea how to do this. I try somethink like this:

this.group.forEach(element => console.log(element)

"this.group" is the subscription of that document. But this output display all content from this document and not the only array called (users)See attachement.

Hope anyone can help?

Answer 1

You can loop it and push it in a new array like this. See sample code below:

    const docSnap = await getDoc(docRef);

    const newArray = [];

    if (docSnap.exists()) {
      const users = docSnap.data().users
      users.forEach(element => {
        newArray.push(element.id);
      })

      // This will return an array of `id` from the `users` array.
      console.log(newArray);
    } else {
      // doc.data() will be undefined in this case
      console.log("No such document!");
    }

The same logic will be applied if you use it to the subscription of the document.