Query stored values that contain specific string

Question

I have a small realtime firebase database that's set up like this:

database
-messages
--XXXXXXXXXXXX
---id : "XXX-XXX"
---content : "Hello world!"

It's a very simple message system, the id field is basically a combination of users id from my mysql database. I'm trying to return all messages that match one of the ids, either sender or receiver. But I can't do it, seems like firebase only support exacts querys. Could you give me some guidanse? Here's the code I'm working with

firebase.database().ref("messages").orderByChild("id").equalTo(userId).on("value", function(snapshot)

I'm looking for something like ".contains(userId)"

score 0 · Answer 1 · answered Jun 02 '21 at 14:13

Firebase supports exact matches (with equalTo) and so-called prefix queries where the value starts with a certain value (by combining startAt and endAt). It does not support querying for values that end with a certain value.

I recommend keeping a mapping from each user IDs to their messages nodes, somewhere separately in their database.

So say that you have:

messages: {
  "XXXXXXXXXXXX": {
    id : "YYY-ZZZ",
    content : "Hello world!"
  }
}

You also have the following mappings:

userMessages: {
  "YYY": {
    "XXXXXXXXXXXX": true
  },
  "ZZZ": {
    "XXXXXXXXXXXX": true
  }
}

Now with this information you can look up the messages for each user based on their ID.

For more on the modeling of this type of data, I recommend:

Best way to manage Chat channels in Firebase
Many to Many relationship in Firebase
this artcle on NoSQL data modeling

Thank you, I'm taking a look, it's quite complex, it seems plain javascript doesn't support mapping also? — Logista, Jun 02 '21 at 14:46
Nope, sorry. I gave up, firebase is more trouble than it's worth, I moved to server sent events may be slower but it behaves like I want it to — Logista, Jun 14 '21 at 14:56

Query stored values that contain specific string

1 Answers1