CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
Satheesh
Satheesh

Reputation: 11276

Firebase Android unable to query item based on object value - returns all values

I have been working on a Firebase backed Android app and this is what my datatbase looks like

{
  "Category" : {
    "-KhHnKaR2oS0JKNrAQWr" : {
      "CategoryDescription" : "Ne est",
      "CategoryName" : "New Test Category",
      "CategoryThumbnail" : "/New Test Category/New Test Category-thumb.jpg",
      "ThumbnailFileType" : "jpg"
    }.......
  },
  "Images" : {
    "-KhHBBI4QloAEBDxcUac" : {
      "Category" : "-KhBGZnCQ5xhYVbP0dtd",
      "-KhBGZnCQ5xhYVbP0dtd":true,
      "CategoryName" : "please",
      "FileType" : "jpg",
      "FileURL" : "/please/NewAddTest.jpg",
      "Name" : "NewAddTest"
    },
    "-KhI1wWJK8YUApa0Iv9q" : {
      "Category" : "-KhHnKaR2oS0JKNrAQWr",
      "-KhHnKaR2oS0JKNrAQWr":true,
      "CategoryName" : "New Test Category",
      "FileType" : "jpg",
      "FileURL" : "/New Test Category/Test Mem.jpg",
      "Name" : "Test Mem"
    }.....
  }
}

And I was able to get categories by referring the key 'Category' and initially I had Cateogry and Images embedded i.e, 

"-Kh8YUXwK0sg3OyoTyAU" : {
  "CategoryDescription" : "The legendary evergreen Vadivelu",
  "CategoryName" : "Vadivelu",
  "CategoryThumbnail" : "/Vadivelu/v2.png",
  "Images":{"-KhH5nJjaji2OtOPVeQF" : {
  "Category" : "-KhBGZnCQ5xhYVbP0dtd",
  "-KhBGZnCQ5xhYVbP0dtd":true,
  "FileType" : "jpg",
  "FileURL" : "/please/New jpg",
  "Name" : "New "
}}
}

It worked out well but in the Firebase docs I read that it is safer to keep data normalized and flattened so then I came up with the latest one at the top. When I try to query like below it returns all objects rather than the desired ones,

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    final DatabaseReference imageRef = database.getReference("Images");
    imageRef.keepSynced(true);
    try {
    imageRef.child("Images").
    orderByChild("Images/Category").equalTo(category.memeCategoryID);
    imageRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
           //Returns all objects.
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

Also I tried to do this,

 imageRef.child(category.CategoryID).equalTo(true);

What I intend to do here is implement by multiple - single relationship and fetch all Images tagged to a category, any help is appreciated. I have seen so many threads and the official Firebase documentation is really confusing and does not help me a bit.

Upvotes: 0

Views: 80

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 598951

When you call orderBy..., equalTo or one of the other methods, Firebase returns a new Query object. So you'll need to capture that query in a new variable:

Query query = imageRef
    .child("Images")
    .orderByChild("Images/Category")
    .equalTo(category.memeCategoryID);

query.addListenerForSingleValueEvent(new ValueEventListener() {

Upvotes: 1

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