Firebase iOS - Query with one part of the compound key - ios

Question

In my Firebase database I use a compound key as the ID for one-to-one conversations in the following format 'UID1_UID2' sorted lexicographically.
When I want to load all conversations via the iOS client for a particular user (UID1) how can I query Firebase when the compound key consists of two combined user IDs.

Answer 1

queryStartingAt("UID1_").queryEndingAt("UID1_")
will return all conversations UID1_ started.
You should be structuring your data as
conversation: UID1_UID2

Answer 2

Compound keys are not that great of an idea. Please consult this part of the documentation that explains how to best model a chat / conversation structure.
Relevant excerpt demonstrating how to structure data for chats:
{
// Chats contains only meta info about each conversation
// stored under the chats's unique ID
"chats": {
"one": {
"title": "Historical Tech Pioneers",
"lastMessage": "ghopper: Relay malfunction found. Cause: moth.",
"timestamp": 1459361875666
},
"two": { ... },
"three": { ... }
},
// Conversation members are easily accessible
// and stored by chat conversation ID
"members": {
// we'll talk about indices like this below
"one": {
"ghopper": true,
"alovelace": true,
"eclarke": true
},
"two": { ... },
"three": { ... }
},
// Messages are separate from data we may want to iterate quickly
// but still easily paginated and queried, and organized by chat
// conversation ID
"messages": {
"one": {
"m1": {
"name": "eclarke",
"message": "The relay seems to be malfunctioning.",
"timestamp": 1459361875337
},
"m2": { ... },
"m3": { ... }
},
"two": { ... },
"three": { ... }
}
}