Firebase query does not allow order on multiple properties? - objective-c

Question

I'm trying to fetch some data from firebase. In my object, I have
Recent
|_UniversitId
|_objectiId1
| |_ userId:1
| |_ timestamp:143242344
|_objectiId2
|_ userId:1
|_ timestamp:143243222
My querying path is http://firbasedbname.com/Recent/UniversityId. I need to fetch the entries which are userId id is equal to 1 and order that set by timestamp. I tried the following,
FIRDatabaseQuery *query = [[firebase queryOrderedByChild:#"userId"] queryEqualToValue:#"1"];
This fetches my the users correctly. But is there a possible way to order this set by timestamp. To do that I tried by putting another queryOrderedByChild. But it says it can be used only one time. How may I fix this?

Answer 1

queryOrderedByChild can be used only once.
a workaround would be
|_objectiId1
| |_ userId:1
| |_ timestamp:143242344
| |_ userId_timestamp:1_143242344
|_objectiId2
|_ userId:1
|_ timestamp:143243222
|_ userId_timestamp:1_143243222
Then try :
FIRDatabaseQuery *query = [[firebase queryOrderedByChild:#"userId_timestamp"] queryEqualToValue:#"1_143242344"];
check this out https://youtu.be/sKFLI5FOOHs?t=541
another way to do it would be :
|_objectiId1
|_ userId1:
| |_ objectId11:143242344
| |_ objectId12:143243222
|_ userId2:
Then
querying path is http://firbasedbname.com/Recent/UniversityId/userId1
and then order by value