1

我正在尝试构建一个消息系统。我计划收集消息,然后根据发送者和接收者查询消息。为此,我需要查询例如:由 Bob 发送并由 Tony 接收的所有消息,以及由 Tony 发送并由 Bob 接收的所有消息。我很不清楚如何做这个“或”陈述。截至目前我有

MessageRef.once('value', function(dataSnapshot) {
  console.log(dataSnapshot.val());
});

返回所有消息。然后我可以做一个 forEach 但它似乎不是很有效。你们有什么建议吗?

另外,您是否对我构建消息系统的模型与拥有聊天室有什么想法?

谢谢

4

1 回答 1

7

Firebase 目前只能查询单个子属性。因此,如果要查询多个属性,则必须将它们合并为一个:

Messages
  -DFHJ3498ua
    from: Tony
    to: Bob
    from_to: Tony_Bob
    message: "Hello Bob, this is Tony"
  -DFHJ3598uz
    from: Bob
    to: Tony
    from_to: Bob_Tony
    message: "Hello Tony, What can I do for you?"
  -EFHJ3498ua
    from: Tony
    to: Bob
    from_to: Tony_Bob
    message: "Can you help me with this Firebase query?"

然后,您可以使用以下命令查询从 Bob 到 Tony 的消息:

var ref = new Firebase('https://your.firebaseio.com/Messages');
var query = ref.orderByChild('from_to').equalTo('Bob_Tony');
query.on('value', function(snapshot) {
  console.log(snapshot.val()); // all messages from Bob to Tony
});

在类似聊天的应用程序中,您可能需要考虑实际使用发送方-接收方对作为密钥:

Messages
  from_Bob_to_Tony
    -DFHJ3598uz
      from: Bob
      to: Tony
      message: "Hello Tony, What can I do for you?"
  from_Tony_to_Bob
    -DFHJ3498ua
      from: Tony
      to: Bob
      message: "Hello Bob, this is Tony"
    -EFHJ3498ua
      from: Tony
      to: Bob
      message: "Can you help me with this Firebase query?"

使用此数据结构,您无需运行查询即可获取相关消息,但可以进行直接查找。

var ref = new Firebase('https://your.firebaseio.com/Messages');
var query = ref.child('from_Bob_to_Tony');
query.on('value', function(snapshot) {
  console.log(snapshot.val()); // all messages from Bob to Tony
});
于 2015-01-20T00:45:28.463 回答