CODEWITHSUNDEEP
androidfirebasefirebase-realtime-databaseandroid-recyclerview
7uthaifah
7uthaifah

Reputation: 345

Firebase show if child exists

I am using FirebaseIndexRecyclerAdapter and I'am trying to show post for the following users so I have used these method blew but It show posts if the post id is available at the following users:

Here's my json:

"Following" : {
    "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" : { 
       "pypD1SYZkbcYesk09WuMUY1AkTf1": true,
      //I need to show this UID posts only but,
      //When I add here post id it show the post 
      //Ex:"-KduqnVVczZf5uibQiZ-" : true,//Post Shows Up
  },
  "Posts" : {
    "-KduqnVVczZf5uibQiZ-" : {
      "Describe" : "gg",
      "Time" : 14881230655,
      "UID" : "pypD1SYZkbcYesk09WuMUY1AkTf1",
      "Username" : "Jone",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped906285501.jpg?alt=media&token=0c1a3a3d-6e48-4c4e-ba59-f5646bf8965f"
    },
    "-Ke5gJ00CxbjhOuhzLIx" : {
      "Describe" : "hajj",
      "Time" : 1488318465,
      "UID" : "pypD1SYZkbcYesk09WuMUY1AkTf1",
      "Username" : "Dom",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1717103943.jpg?alt=media&token=a85b2488-5ac7-49a7-9ad0-dbf4e6f29389"
    },
    "-KeCuiFmUCpN19zwsTsR" : {
      "Describe" : "a",
      "Profile" : "https://lh4.googleusercontent.com/-suB77riNoX8/AAAAAAAAAAI/AAAAAAAAAAA/ADPlhfKMzINn-Ki538Sqf6SRGaXC81-WuQ/s200-c/photo.jpg",
      "Time" : 1488439652,
      "UID" : "z2SNUlLd6mQM8nnlkU2VUws5Ggl2",
      "Username" : "Dom",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1913886685.jpg?alt=media&token=c8ad26b2-8f09-453b-b48a-aad9e4d8b5c3"
    },
    "-KeD2fBUQ09HVMrvAneb" : {
      "Describe" : "ee",
      "Profile" : "https://lh4.googleusercontent.com/-suB77riNoX8/AAAAAAAAAAI/AAAAAAAAAAA/ADPlhfKMzINn-Ki538Sqf6SRGaXC81-WuQ/s200-c/photo.jpg",
      "Time" : 1488441999,
      "UID" : "z2SNUlLd6mQM8nnlkU2VUws5Ggl2",
      "Username" : "Dom",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1904338270.jpg?alt=media&token=d200b7fc-15e7-4dc4-9913-59c377929e9e"
    },
    "-KeDfnMWiB7k_4J3FBgZ" : {
      "Describe" : "f12g",
      "Time" : 1488452517,
      "UID" : "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" 
      "Username" : "Young",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1872832638.jpg?alt=media&token=80239844-a872-47e2-9689-92d368dd9452"
    },
    "-KeDfrw4inUQFtIDXJHp" : {
      "Describe" : "fg",
      "Time" : 1488452536,
      "UID" : "ORBBKfZAAUhqI1h7ojQDzYOjgkp1" 
      "Username" : "Young",
      "Wallpaper" : "https://firebasestorage.googleapis.com/v0/b/test-3f4c5.appspot.com/o/Posts%2Fcropped1872832638.jpg?alt=media&token=80239844-a872-47e2-9689-92d368dd9452"
    },

  }
}

And here's my method that I use:

    mAuth = FirebaseAuth.getInstance();
    mCurrentUser = mAuth.getCurrentUser();
    mDatabase = FirebaseDatabase.getInstance().getReference().child("Posts");
    mDatabaseFriends = FirebaseDatabase.getInstance().getReference().child("Following").child(mCurrentUser.getUid());

   FirebaseIndexRecyclerAdapter<Getting_Posts,PostViewHolder> firebaseIndexRecyclerAdapter = new FirebaseIndexRecyclerAdapter<Getting_Posts, PostViewHolder>(
            Getting_Posts.class,R.layout.post_card_design,PostViewHolder.class,mDatabaseFriends,mDatabase)
    {
        @Override
        protected void populateViewHolder(PostViewHolder viewHolder, Getting_Posts model, int position) {}};

Upvotes: 0

Views: 383

Answers (1)

Francisco Durdin Garcia
Francisco Durdin Garcia

Reputation: 13327

To check if a fiven reference have childrens you should use dataSnapshot.exists() or dataSnapshot.getChildrenCount() > 0 with the given DataSnapshot on your callback.

If you want to retrieve the post which id is equal to the followers you should modify your database adding an extra level to pur Posts table where the post will be already together based on a user id:

"Posts": {
"USER_ID_1": {
  "post_id_1": {
    "Describe": "gg",
    "Time": 14881230655,
    "UID": "pypD1SYZkbcYesk09WuMUY1AkTf1",
    "Username": "Jone"
  },
  "post_id_2": {
    "Describe": "gg",
    "Time": 14881230655,
    "UID": "pypD1SYZkbcYesk09WuMUY1AkTf1",
    "Username": "Jone"
  }
},
"USER_ID_2": {
  "post_id_3": {
    "Describe": "gg",
    "Time": 14881230655,
    "UID": "pypD1SYZkbcYesk09WuMUY1AkTf1",
    "Username": "Jone"
  },
  "post_id_4": {
    "Describe": "gg",
    "Time": 14881230655,
    "UID": "pypD1SYZkbcYesk09WuMUY1AkTf1",
    "Username": "Jone"
  }
}

To iterate looking to get all the posts inside each of your user's(just if you are following the new data model that I post you upside), you can retrieve them doing this:

        List<Getting_Posts> totalPosts = new ArrayList<>();
        //Check if the dataSnapshot have childrens
        if (dataSnapshot.hasChildren()){
           //This for iterate for each USER_ID from your database
           for (DataSnapshot users : dataSnapshot.getChildren()) {
              //This second iterate for each post for each user
              for (DataSnapshot posts : users.getChildren()) {
                 totalPosts.add(dataSnapshot.getValue(Getting_Posts.class));
              }
           }
        }

        return totalPosts;

You can read more about this in the next post or in the oficial documentation: https://www.airpair.com/firebase/posts/structuring-your-firebase-data

https://firebase.google.com/docs/database/web/structure-data?hl=en-419

Upvotes: 1

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