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
});