How to get a selected list of documents on a Firebase list?

Asked Sep 13 '16 at 16:43

Active Sep 13 '16 at 16:55

Viewed 129 times

I have a list on Firebase

list: {
  -firebasepushid1: {...},
  -firebasepushid2: {...},
  -firebasepushid3: {...},
  -firebasepushid4: {...},
  -firebasepushid5: {...},
  -firebasepushid6: {...},
  ...
}

I know I can get the whole list with db.ref("list/") or a especific document db.ref("list/-firebasepushid1").

What If I want to get 3 especific documents?

I think 2 ways but they would cause overload on the server I guess:

Making a loop for the 3 documents separately
Get the whole list and seek on the client

It would be ideal to do this with a single query to the server. You have some way?

edited Sep 13 '16 at 16:55

Dravidian

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asked Sep 13 '16 at 16:43

Rodolfo Paranhos

1

Add the tag of the language in which you are coding – Dravidian Sep 13 '16 at 16:54
Javascript..... – Rodolfo Paranhos Sep 13 '16 at 16:54
1

Would you know those 3 specific id beforehand? Or you want selection of 3 id nodes in each iteration – Dravidian Sep 13 '16 at 16:56
@Dravidian beforehand. – Rodolfo Paranhos Sep 13 '16 at 17:41
Looping over the IDs and requesting the documents separately is not significantly slower than requesting them with a single `WHERE id IN (1,2,3)` query on Firebase. This is because Firebase pipelines the requests/responses. See http://stackoverflow.com/questions/35931526/speed-up-fetching-posts-for-my-social-network-app-by-using-query-instead-of-obse/35932786#35932786 – Frank van Puffelen Sep 13 '16 at 18:37
@FrankvanPuffelen Its ok for me to set all the "db.ref().on()" separately? – Rodolfo Paranhos Sep 13 '16 at 18:58
@FrankvanPuffelen Resuming: getting a new data query in Firebase doesn't mean opening a new pipeline, yes? – Rodolfo Paranhos Sep 13 '16 at 19:07
1

That's correct. It all goes over a single socket. So the overhead of setting up the connection is only occurred on startup (or upon a reconnect) and all requests are then pipelined over that connection. – Frank van Puffelen Sep 13 '16 at 19:09

How to get a selected list of documents on a Firebase list?

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