Firebase functions search query realtime database with nodejs

Question

This is my database

"Users" : {
        "2rnWA7TF11gSWxec7MsCA5iRhjw1" : {
          "favoriteCount" : 1,
          "interest" : [ "dogs", "cats", "technology" ],
          "speciality" : [ "Swift" ],
        },
        "3Id9oX0ZOEM00XJlnR07gGrHs762" : {
          "favoriteCount" : 7,
          "interest" : [ "dogs", "cats", "Asp.NET MVC", "JavaScript" ],
          "speciality" : [ "Microsoft Technologys" ],

      }

I want to access user information interest=dogs in whole database how can I do?

score 2 · Answer 1 · answered May 14 '18 at 14:07

2

Your current data structure allows you to easily look up the interests for a specific user. It does not however allow easy lookup for the users for a specific interest.

To allow looking up the users for an interest, you'll want to add an inverted data structure /Interests/$interest with the user ID for each user under there:

"Interests": {
  "dogs": {
    "2rnWA7TF11gSWxec7MsCA5iRhjw1": true,
    "3Id9oX0ZOEM00XJlnR07gGrHs762": true
  },
  "cats": {
    "2rnWA7TF11gSWxec7MsCA5iRhjw1": true,
    "3Id9oX0ZOEM00XJlnR07gGrHs762": true
  },
  "technology": {
    "2rnWA7TF11gSWxec7MsCA5iRhjw1": true,
  }
  ...
}

Also see:

answered May 14 '18 at 14:07

Frank van Puffelen

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it does not seem possible because I do not have a specific area – Ahmet Saz May 14 '18 at 14:30
Sorry, I don't understand. Can you rephrase that? – Frank van Puffelen May 14 '18 at 14:38
I don't have a specific dog and cat area,each user can create a desired field – Ahmet Saz May 14 '18 at 14:43
@FrankvanPuffelen I like the "**vintage** blog post"!! :-))) – Renaud Tarnec May 14 '18 at 14:46
@AhmetSaz: This is the idiomatic way to solve categorization-queries in Firebase's realtime database. The keys in my additional data structure can also be create ad-hoc as needed. – Frank van Puffelen May 14 '18 at 15:44

score 0 · Answer 2 · answered May 14 '18 at 13:58

You can make queries in Firebase:

Query query = usersDB.orderByChild("interest").equalTo("WHATEVERINTEREST");

query.addListenerForSingleValueEvent(new ValueEventListener() {
   @Override
   public void onDataChange(DataSnapshot dataSnapshot) {
     Users user = dataSnapshot.getValue(Users.class);
     doWhatever();
   }
});

However in your case as you store the information as an Array, what you can do is retrieve all the users and in your code get the information you need.

 usersDB.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                ArrayList<Users> listOfUsers = new ArrayList<Users>();

                for (DataSnapshot dsp : dataSnapshot.getChildren()) {

                    Users user = dsp.getValue(Users.class);
                    listOfUsers.add(user);
                }

                //Check the Users that contains interest
                usersWithInterest(listOfUsers,"dogs");

            }


        });

Implement an easy method that read all the list of users and check the users with a interest in dogs:

 usersWithInterest(listOfUsers, "dogs");

The concept is the same, just make it in nodeJS. Nevertheless I would strongly recommend use the approach @FrankvanPuffelen used in his answer. Is more efficient. — Alex Bean, May 14 '18 at 15:19

Firebase functions search query realtime database with nodejs

2 Answers2