Firebase .queryStarting not working (Swift) - ios

Question

This just isn't returning anything even though there are messages with timestamps above this one.
Code not properly sorting:
let messagesRef = FIRDatabase.database().reference().child("all-messages").child(messageId).queryOrdered(byChild: "timestamp").queryStarting(atValue: 1511130644)
Full code of Firebase calls:
FIRDatabase.database().reference().child("users").child(currentUserUid).child("timestampOfLastVisit").observeSingleEvent(of: .value, with: { (snapshot) in
timestamp = snapshot.value as! NSNumber
groupMessagesRef = FIRDatabase.database().reference().child("groups").child(groupId).child("messages")
groupMessagesRef.observe(.childAdded, with: { (snapshot) in
if self.sentMessage {
let messageId = snapshot.key
let messagesRef = FIRDatabase.database().reference().child("all-messages").child(messageId).queryOrdered(byChild: "timestamp").queryStarting(atValue: 1511130644)
messagesRef.observeSingleEvent(of: .value, with: { (snapshot) in ...
Relevant Firebase JSON (fake data obviously):
{
"all-messages" : {
"-KzLOuvEdLWy7vfc2XsT" : {
"fromId" : "zhBZyAVGvAMZWi4QhvKDu7qb3Qr1",
"groupId" : "-Kxk3kA9I8OEvNmFcavL",
"isStarred" : true,
"text" : "This should show",
"timestamp" : 1511130640
},
"-KzLOw5OxZ4P_I0d70gZ" : {
"fromId" : "zhBZyAVGvAMZWi4QhvKDu7qb3Qr1",
"groupId" : "-Kxk3kA9I8OEvNmFcavL",
"isStarred" : false,
"text" : "And so should this",
"timestamp" : 1511130644
},
"-KzLS4uwDtpW6wHNxrmc" : {
"fromId" : "zhBZyAVGvAMZWi4QhvKDu7qb3Qr1",
"groupId" : "-Kxk3kA9I8OEvNmFcavL",
"isStarred" : false,
"text" : "1",
"timestamp" : 1511131471
},
"-KzLS5FvASnj_ky4WQkd" : {
"fromId" : "zhBZyAVGvAMZWi4QhvKDu7qb3Qr1",
"groupId" : "-Kxk3kA9I8OEvNmFcavL",
"isStarred" : false,
"text" : "2",
"timestamp" : 1511131472
}
},
"groups" : {
"-Kxk3kA9I8OEvNmFcavL" : {
"groupCreator" : "zhBZyAVGvAMZWi4QhvKDu7qb3Qr1",
"groupDescription" : "Group",
"groupImageUrl" : "https://firebasestorage.googleapis.com/v0/b/groupchat1-a1da3.appspot.com/o/group_profile_images%2FA4DDA286-E7A3-4F96-ABF0-5717F4029C33.png?alt=media&token=6ad79728-74fd-405f-abbf-247dae4684b5",
"groupMemberOneSignalIds" : {
"5905a2f5-dfa3-46d7-964f-596bd2f2004a" : true,
"67b9cb2a-6583-45b4-9fed-93cf333e9ca4" : true,
"a1bf9ed9-0959-4c88-974b-5a829c1cdcc9" : true,
"f2fb84b9-86af-40e7-8667-989a95b2e282" : true
},
"groupMembers" : {
"3lQiuzudFGW51UwQ4Mseu8aOxyu2" : true,
"JF7SCe3VUcWJi1ujumx0VpyaG5s1" : true,
"YEbVehx0cqTvNaKrJTcs5GnRLGM2" : true,
"zhBZyAVGvAMZWi4QhvKDu7qb3Qr1" : true
},
"groupName" : "1",
"groupTags" : {
"-Kxk3kHxMuWQHEsaWN5k" : "1",
"-Kxk3kHyMB2OL5pNAfW1" : "1",
"-Kxk3kHyMB2OL5pNAfW2" : "1"
},
"messages" : {
"-KzLOuvEdLWy7vfc2XsT" : 1,
"-KzLOw5OxZ4P_I0d70gZ" : 1,
"-KzLS4uwDtpW6wHNxrmc" : 1,
"-KzLS5FvASnj_ky4WQkd" : 1
},
"starredMessages" : {
"-KzLOuvEdLWy7vfc2XsT" : 1511204335
}
},
"-Kxn_yTAZvkPls-_s8He" : {
"groupCreator" : "JF7SCe3VUcWJi1ujumx0VpyaG5s1",
"groupDescription" : "Group 3",
"groupImageUrl" : "https://firebasestorage.googleapis.com/v0/b/groupchat1-a1da3.appspot.com/o/group_profile_images%2FD2C68A8F-33DC-43C6-8C99-762315760208.png?alt=media&token=aae87339-877e-484e-a0e1-a2e13455176c",
"groupName" : "Group 3",
"groupTags" : {
"-Kxn_ygovR7mQIph3WiC" : "1",
"-Kxn_ygovR7mQIph3WiD" : "1"
}
}
},
"users" : {
"JF7SCe3VUcWJi1ujumx0VpyaG5s1" : {
"email" : "Madi#gmail.com",
"groups" : {
"-Kxk3kA9I8OEvNmFcavL" : true,
"-Kxk3n99i43MYECm1Ix8" : true,
"-KxuBPAPBIcROMEtNujW" : true,
"-KxuET1pZGg2x_aJvRkU" : true
},
"profileImageURL" : "https://firebasestorage.googleapis.com/v0/b/groupchat1-a1da3.appspot.com/o/profile_images%2F246CA55C-446D-4A24-8BE6-8B5B9C0F27AF.png?alt=media&token=47022ccd-1c92-460a-8630-e74a0d68bc4a",
"searchUsername" : "madi",
"timestampOfLastVisit" : 1511241228,
"username" : "Madi"
},
"zhBZyAVGvAMZWi4QhvKDu7qb3Qr1" : {
"email" : "Connor#gmail.com",
"groups" : {
"-Kxk3kA9I8OEvNmFcavL" : true,
"-Kxk3n99i43MYECm1Ix8" : true
},
"profileImageURL" : "https://firebasestorage.googleapis.com/v0/b/groupchat1-a1da3.appspot.com/o/profile_images%2FBDC4020E-9F54-4F80-A4DC-668804215DE3.png?alt=media&token=ec2c8875-e6e4-40d5-8c07-3d743bf4ea16",
"searchUsername" : "connor",
"timestampOfLastVisit" : 1511205356,
"username" : "Connor"
}
}
}
What print(snapshot) prints:
Snap (-KzLOw5OxZ4P_I0d70gZ) <null>
print(messageRef):
(/all-messages/-KzLOw5OxZ4P_I0d70gZ {
i = timestamp;
sp = 1511130644;
})

Answer 1

The goal is to create a query that will return the node that has a particular time stamp.
The problem is your code is querying one level too deep. In other words, you need to let Firebase iterate over the child nodes of all-messages until it finds one that has a child timestamp of 1511130644. So it will need to iterate over
msg_0
msg_1
msg_2
etc.
Your code is trying to be too specific and you are telling it to look at a particular message Id for the data in the query - which doesn't make sense as if you know the exact path, you wouldn't need to query!
This is a common misunderstanding - just remember that queries need to be provided the parent node and then the child node of what you are querying for as it will then iterate over the child_nodes just underneath the parent.
parent_node
child_node
child_node_of_what_you_are_querying
child_node
child_node_of_what_you_are_querying
Here is code to query for a certain time stamp - note the messageId is not needed
//self.ref is the firebase ref
let messagesRef = self.ref.child("all-messages").queryOrdered(byChild: "timestamp")
.queryStarting(atValue: 1511130644)
messagesRef.observeSingleEvent(of: .value, with: { (snapshot) in
if snapshot.hasChildren() {
print("got snap with children")
} else {
print("no snap found")
}
})
If you already know the specific path you can observe it directly. So if you want to print the timestamp for a certain message
let thisMsgRef = self.ref.child("all-messages").child(messageId)
let thisTimestampRef = thisMsgRef.child("timestamp")
thisTimestampRef.observeSingleEvent(of: .value) { snapshot in
print(snap.value) //prints the timestamp
}

Answer 2

The second argument to queryStartingAtValue() is only used to disambiguate between items that match the first argument. To filter by timestamp you should call queryOrderedByChild("timestamp"):
let messagesRef =
FIRDatabase.database().reference().child("all-messages").child(messageId)
.queryOrdered(byChild: "timestamp")
.queryStarting(atValue: 1511130644)