How to create an index on a child property of an array object in Firebase

Question

In my firebase app I am storing objects in an array structure using the push() method that generates unique ids. These objects have a child property called "scheduledDate" How can I create an indexOn rule in firebase to index this field. under events each user has a node, than a child array of their events. /events/userId/arrayOfEvents

I can use orderByChild() to successfully retrieve the records by event scheduled date, but its warning me about the index.

My rules looks like this:

   "events":{
      ".read" : "auth != null",
      ".write" : "auth != null",
      ".indexOn": ["scheduledDate"]
    }

My code doing the query looks like this:

         this.dbEvents = new Firebase(firebaseEventsUrl);

         var q;

         q = this.dbEvents.child(userId).orderByChild("scheduledDate").limitToLast(limitToLast);

         return $firebaseArray(q);

My data looks like this:

          events:{
              user1:{
                  -K2NYCT2_uMwsTSfH58O(push generated):{
                      description: 'event 1',
                      scheduledDate: 1446730200000
                  },
                  --K2NyNh660I4k8loar-z:{
                      description: 'event 2',
                      scheduledDate: 1446730200000
                  },
              },
              user2:{

              }
          }

Descriptions of data or code are not the same as actual data/code. Please show a sample of your data (no screenshot please) and the code that you use to query it. — Frank van Puffelen, Nov 06 '15 at 18:53
edited to show code and data structure I am working with. Again, it works, just warns me I need to index scheduledDate, and I don't know how to create that indexOn rule for a level this deep. — Stradosphere, Nov 06 '15 at 22:19

Frank van Puffelen · Accepted Answer · 2015-11-07T01:49:28.290

28

This should work:

{
  "rules": {
    "events":{
      ".read" : "auth != null",
      ".write" : "auth != null",
      "$uid": {
        ".indexOn": "scheduledDate"
      }
    } 
  }
}

edited Nov 07 '15 at 01:49

answered Nov 06 '15 at 22:40

Frank van Puffelen

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I get this: FIREBASE WARNING: Using an unspecified index. Consider adding ".indexOn": "scheduledDate" at /events/simplelogin:82 to your security rules for better performance – Stradosphere Nov 06 '15 at 23:33
Ah, I now see that you have a level for users in there. I'll update. – Frank van Puffelen Nov 07 '15 at 01:48
2

This works, thanks Frank! Can the "$uid" be named anything as a variable to represent that level? – Stradosphere Nov 07 '15 at 02:46
2

Yup, it's just a variable name. Please read this section of the docs: https://www.firebase.com/docs/security/guide/securing-data.html#section-dollar-variables – Frank van Puffelen Nov 07 '15 at 03:55
Can someone tell the best place to place the above code? – Charles Jr Feb 22 '16 at 05:14
this really helped me – RJH Dec 04 '16 at 21:37
@FrankvanPuffelen Thanks for your answer. I tried to add the rule to existing data but the query doesn't get any faster. My question is how long does it take for Firebase to index all the existing data? – Hai nguyen thanh Mar 30 '17 at 13:17

How to create an index on a child property of an array object in Firebase

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