Firebase iOS-使用复合键的一部分进行查询

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": { ... }
  }
}