Angularfire2/Firebase - query with angularfire2 list subscribe on runtime not working

Question

I am working on a project with angular2/firebase and using angularfire2 module. I want some realtime data so I use angularfire2 list and on component side using subscribe over the list. In real-time scenario, if any new item added in firebase database it subscribe but without any query. How I can archive subscribe with query? I am using following code where the query is some selection on which basis I want data.

getRealtimeData(query: any){
    if(query){
        return this.af.database.list(databaseName+"/messages", {
            query: {
                orderByChild: 'is_broadcast',
                equalTo: query.value
            }
        });
    } else {
        return this.af.database.list(databaseName+"/messages", {
            query: {
                orderByChild: 'timestamp'
            }
        });
    }
}

I am calling this in my component creating a query

      var query;
      if (this.isBroadcastMessage && this.isGroupChatMessage || !this.isBroadcastMessage && !this.isGroupChatMessage) {
          query = null;
      } else if (this.isBroadcastMessage && !this.isGroupChatMessage) {
          query = {
              value: true
          };
      } else if (!this.isBroadcastMessage && this.isGroupChatMessage) {
          query = {
              value: false
          };
      }
      this.firebaseService.getRealtimeData(query).subscribe((data: any) => {
          console.log("data::", data);
      }, (error: any) => {
          console.log("error::", error);
      })

can you provide the Component code which use this getRealtimeData method? and also some logs of the object you receive? — nisanarz
– nisanarz, Commented Jun 6, 2017 at 13:01
Added in description, i want my subscribe get called with query. but it not getting called with query — Puneet Gupta
– Puneet Gupta, Commented Jun 7, 2017 at 4:57
weird, i tried this before, and its worked for me. the only difference is that i made the DB list query inside my component and not in the service. you tried to do that? — nisanarz
– nisanarz, Commented Jun 7, 2017 at 6:30
Yes, but that will not make sense as subscribe always call without query :( — Puneet Gupta
– Puneet Gupta, Commented Jun 8, 2017 at 6:09

nagabandaru · Accepted Answer · 2017-09-08 17:43:22Z

1

User ReplaySubject

query$: ReplaySubject<any> = new ReplaySubject(1);

First, create your getRealtimeData function like this like this

// you no need to pass any argument here
getRealtimeData():FirebaseListObservable<any>{
    return this.af.database.list(databaseName+"/messages", {
        query: this.query$
    });

then

public updateQuery(query: string): void {
  this.query$.next(query);
}

Now

 this.firebaseService.getRealtimeData().subscribe((data: any) => {
      console.log("data::", data);
  }, (error: any) => {
      console.log("error::", error);
  })

subscribe function will be called when ever you call

this.firebaseService.updateQuery({
            orderByChild: 'is_broadcast',
            equalTo: true // false
        });
// or
this.firebaseService.updateQuery({
            orderByChild: 'timestamp'
        });

edited Sep 8, 2017 at 17:43

answered Sep 8, 2017 at 11:41

nagabandaru

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