How to query an array list in a Firebase document?

Question

I'm trying to query my database for an android application, if a username is in the 'fave' array field of my database and if so then change the background of an image. My database is set up like this...

I don't know if i'm doing it right but currently i think i may be checking the whole collection rather than a specific document and it's not even returning anything. Any suggestions would be appreciated!

I suggest starting with the documentation to learn how to do queries. firebase.google.com/docs/firestore/query-data/queries — Doug Stevenson
– Doug Stevenson, Commented Apr 9, 2020 at 18:27
@DougStevenson sorry maybe i should have been more clear. In the documentation the query objects search a whole collection but i only want to search a specific document, as the user can be in multiple trainers 'fave' arrays — Ezan
– Ezan, Commented Apr 9, 2020 at 18:32
Then just get() the document you're looking for. firebase.google.com/docs/firestore/query-data/get-data — Doug Stevenson
– Doug Stevenson, Commented Apr 9, 2020 at 18:33
@DougStevenson if i add the .document() path afterwards i can no longer use the .whereInArray()_ — Ezan
– Ezan, Commented Apr 9, 2020 at 18:33
Yes, you can't filter when identifying a specific document. There's no need to - you already know the document ID. — Doug Stevenson
– Doug Stevenson, Commented Apr 9, 2020 at 18:52

Jamaldin Sabirjanov · Accepted Answer · 2020-04-09 18:35:32Z

1

You wanted this?

FirebaseFirestore.getInstance().collection("Trainers").document("Air Force 1 Low").get().addOnSuccessListener(new OnSuccessListener<DocumentSnapshot>() {
    @Override
    public void onSuccess(DocumentSnapshot documentSnapshot) {
        List<String> list = (List<String>)documentSnapshot.get("fave");
        for (String name : list){
            if (name.equals("Admin")){
                //do if user is admin
                return;
            }
        }
        //do if user is not admin
    }
});

answered Apr 9, 2020 at 18:35

Jamaldin Sabirjanov

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1 Comment

Ezan Over a year ago

Top lad. I've been struggling to get my head round how to query documents but this has helped a lot. Thanks!

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