I would like to check that I am indexing my relational data correctly, as I am trying to wrap my head around Firebase. I have a two way relationship between users and addresses, both are one to one. The idea is that the user node is initially created with just their email, then when they add their address, a key for the addressID is added to the user node and simultaneously, a key for the userID is added to the address node. This is meant to be similar to how it is recommended in the "Structure Data" section of the Firebsae docs (at the bottom). However, to identify the address within the user node and to identify the user within the address node, I have used their auto generated key (i.e. address: userAutoID, user: addressAutoID; rather than userAutoID: true and addressAutoID: true; as the former is more descriptive and easier to understand. The use of an autogenerated ID as a key doesnt indicate what the key represents). The JSON structure is as follows (both nodes are children of the top-most node):
As you can see the address possesses the user's ID, and the user possesses the address ID. I feel as though the code I have used to achieve this is protracted and I could be going about this the wrong way. The code is triggered when the user has filled out a form for their address and they press submit. Hence, the User node exists before the address node. I use a for loop to sequentially obtain the key of each address that exists, which i then feed into another query, which then looks to find if the current user's ID exists whithin the current address node as the value of the userID key. If this is true, then I set the ID of the current address to the value of the addressID within the current users associated node. Here is the code:
self.rootRef.child("Addresses").observeSingleEvent(of: .value, with: { snapshot in
for address in snapshot.children {
guard let addressSnapshot = address as? FIRDataSnapshot else {
print("failed to get addressSnapshot")
return
}
let addressSnapshotKey = addressSnapshot.key
self.rootRef.child("Addresses").child(addressSnapshotKey).observeSingleEvent(of: .value, with: { snapshot in
guard let snapshotValue = snapshot.value as? [String: AnyObject] else {
print("error getting snapshotValue")
return
}
let userID = FIRAuth.auth()?.currentUser?.uid
if (snapshotValue["userID"] as! String) == userID {
let correctKey = addressSnapshotKey
let userRef = self.rootRef.child("Users").child(userID!)
userRef.child("addressID").setValue(correctKey)
}
})
}
})
I can see that running two queries from one piece of code, may become expensive when the User and Addresses node become very large. Any feedback would be greatly appreciated!
I would reuse the auto generated User key as the key under Addresses as well.
- Users
- xyz (auto generated)
- email: jo#jo.com
- Addresses
- xyz (use the previously created id here too)
- street
- author
- lat
- lon
Related
here is my database
I have a users collection with documents as each user
the issue is that, whenever I change a field by using the actual database editing tool, my app is not able to access data
when I query these fields I get the data that was there before I edited it
if let document = document {
if let username = document.get("user_username") as? String,
let action = document.get("status") as? String,
let description = document.get("status_desc") as? String,
let companion = document.get("user_username") as? String {
ViewController.myName = username
self.helloLabel.text = username + " "
self.actionArray.append(action)
self.actionArray.append(description)
self.actionArray.append(companion)
} else {
print("missing fields in the status")
}
} else {
print("Document does not exist in cache")
}
}
when I print the status field now, I get the string that was there before, which was not "sleeping"
I am also confused because when I update the fields through the app itself, the database would look exactly the same, but the app is capable of detecting the change and shows the new field
can some one explain why this is happening, or how I would fix this issue
Set a listener to receive data-change events in order to listen to realtime changes of a documents with the onSnapshot() method instead of get().
The listener will receive an initial snapshot of the data and another snapshot every time the content changes.
link:
GET realtime updates with Cloud Firestore
First time asking a question here, so sorry if I do it wrong.
Anyways. I'm using Firebase Database to store "Results" in my Quiz app. When data is store it looks like this
Results
-LjQ34gs7QoL1GMufiMsaddclose
Score: xx
UserName: xx
-LjQ3NeCoDGob8wnhstH
Score: xx
UserName: xx
I would like to access score and username from it and display it in a HighScore tableview. Problem is - I can get the "Results" node, but because of the id of the results (ie LjQ34gs7QoL1GMufiMsaddclose) I don't know how to access the score and username.
I got the data snapshot​, but not sure how to "bypass" the id to get to score and username.
Hope I made it at least a bit clear, what the problem is.
let ref = Database.database().reference().child("Results")
ref.observe(.value) { (DataSnapshot) in
print(DataSnapshot.value as Any)
}
You current code gets you a single snapshot with the results of all users. You'll need to loop over the child snapshots to get the result of each user, and then look up their specific properties with childSnapshot(byName:):
let ref = Database.database().reference().child("Results")
ref.observe(.value) { (snapshot) in
for case let userSnapshot as DataSnapshot in snapshot.children {
print(userSnapshot.childSnapshot(forPath: "Score").value)
}
}
Also see:
How to get all child data from firebase without knowing the path
Iterate through nested snapshot children in Firebase using Swift
How do I loop through and get all the keys of the nested nodes in firebase?
Retrieving Data using Firebase Swift
And probably some more from this list.
I have this schema in my firebase :
I have a node articles under it have the ids of users, under one id I have a wishlist name then the articles and the wishlist info, So when I want to change the wishlist name I take the children of the node I want to change then I create w new one with the new name and the same children then I remove the old wishlist. So I want to create a transaction to do all the work in same time or not to do it at all if there is a bad connection because I can loose the data if the operation is interrupted. This is my current code and how I can put the operation in a firebase transaction. Thank you for your help !
func updateWishlist(wishlist:WishList,newName:String){
if((reachability.connection == .wifi) || (reachability.connection == .cellular)){
self.showProgressView()
let child = self.ref.child("Articles").child((user!.uid)!)
self.ref.child("Articles").child((user!.uid)!).child(wishlist.name) .updateChildValues(["name":newName]) { error, _ in
if(error == nil){
//create new node with new name
let oldName=wishlist.name
child.child(wishlist.name).observeSingleEvent(of: .value, with: { (snapshot) in self.ref.child("Articles").child((GlobalVar.user!.uid)!).child(newName).setValue(snapshot.value as! [String : Any]) { error, _ in
if(error == nil){
self.dismissHUD(isAnimated: true)
self.title=newName
self.showMessage("Wishlist modifier !", type: .success, options: [.position(.bottom)])
self.ref.child("Articles").child((GlobalVar.user!.uid)!).child(oldName).removeValue()
}
else{
self.dismissHUD(isAnimated: true)
print("update wishlist name transaction failed")
}
}
user?.wishLists[self.passedWishlistIndex!].name=newName
})
}
self.dismissHUD(isAnimated: true)
}
}
}
This issue really comes down to this statement
I want to change the wishlist name I take the children (out) of the node I
want to change then I create a new one with the new name and the same
children then I remove the old wishlist
The fix is to not use dynamic data as node keys. Restructuring your data will eliminate the need for a transaction.
The wishlist name should be stored as a child of the node with a key created with .childByAutoId.
To clarify, your structure is currently this
Articles
article_0
dadoune //wish list name
solo //with list name
articles
xxx
yyy
zzz
artical_1
artical_2
and here's what will work; move the wish list name to a child node.
Articles
article_0
-Jk0ksk0kj9sdfsdf //wish list key created with .childByAutoId
wish_list_name: "dadoune" //store the name as a child
-Jyl909m9mm3o99jt //wish list key created with .childByAutoId
wish_list_name: "solo" //store the name as a child
articles
xxx
yyy
zzz
article_1
article_2
By storing the dynamic wish list name as a child, you can simply change it whenever you want without having to read the node, delete the node, change the name, and re-write the node.
I my database structure userDatabase/userID/Customers I have two customers. For example path:
usersDatabase
g8voYf1yoChnpmhkoPgtmO4FQT62 - (uid)
Customers
Tom Smith (customer with custom ID)
-LDFZw1tca8KOrnqyyWH - (auto id of customer child)
Status of Service: "Open service"
Ben Thomas (customer with custom ID)
-LDFZw1tca8KOjgoenBN - (auto id of customer child)
Status of Service: "Open service"
Is possible to fetch count of value "Open service" form all customers in my database? Now I only know, how to print this value for each customers...
My code to get value from Database:
let userID = Auth.auth().currentUser?.uid
let usersDatabaseRef = Database.database().reference().child("usersDatabase").child(userID!).child("Customers")
usersDatabaseRef.observe(.value, with: { snapshot in
var totalCustomerCount = 0
for child in snapshot.children {
let childSnap = child as! DataSnapshot
let childrenRef = childSnap
totalCustomerCount += Int(childrenRef.childrenCount)
print("user \(childSnap.key) has \(childrenRef.childrenCount) customers")
let userCustomerSnap = childSnap
for customer in userCustomerSnap.children.allObjects as! [DataSnapshot] {
let customerSnap = customer
let dict = customerSnap.value as! [String: Any]
let stat = dict["Status of Service"] as! String
let myStatistic = PrintModel(status: stat)
self.statistic.append(myStatistic)
print("Statistic: \(String(describing: myStatistic.status))")
}
}
print("... and there are \(totalCustomerCount) total customers")
})
For example my log now show:
user Tom Smith has 1 customers
Statistic: Optional("Open service")
user Ben Thomas has 1 customers
Statistic: Optional("Open service")
but I want to show:
Statistic: 2
When structuring Firebase data, the structure is generally based on what you want to get out of it. In this case the data you want is too deep within the posted structure to be useful. So, changing the structure will make this a snap.
Separate your data into their own nodes, denormalizing the data. Like this
users
uid_0
//some info about this user
open_service_calls
auto_id_0: true
auto_id_1: true
uid_1
//info about this user
customers
customer_id_0
customer_name: "Tom Smith"
open_service_calls
auto_id_0: true
customer_id_1
customer_name: "Ben Thomas"
open_service_calls
auto_id_1: true
service_calls
auto_id_0
customer_id: customer_id_0
user_id: "uid_0"
status_of_service: "Open service"
auto_id_1
customer_id: customer_id_1
user_id: "uid_0"
status_of_service: "Open service"
That allows for queries by customer, user, and to address this question, an easy count of all Open Service in the database for all users and customers; query the service_calls/status_of_service for "Open service"
It also allows you to quickly access all service calls, open or closed for any user, any customer and even just open service calls for a users's customer.
Additional nodes would offer further query flexibility - storing the user id within the customer node would allow a super easy query to retrieve all of the customers for a specific user even if they have no service calls; it all depends on what you want to get out of Firebase.
--- Old answer is below ---
Per my comment to the original question, this answer involves using a Deep Query to query a child of child node of customers. The idea here is that within the user node, there's a Customers node where each child key is a customer name and the value of that node is a key: value pair of the string "serviceID" and then a value which may contain other child nodes about the service.
The important part of a Deep Query is to keep the child keys you are query'ing named consistently - in this case we use the key 'serviceID' so the query can properly resolve the path and then any of the child nodes of that can be queried: status_of_service, perhaps a time stamp or even the service location
The initial structure before it was changed was
Customers
Tom Cruise
serviceID
status_of_service: "Open service"
//timestamp of service?
//location of service?
//other data about service we may need to query?
Ben Smith
serviceID:
status_of_service: "Open service"
Note that for this answer self.ref = my firebase so Customers is a direct child of that path.
let ref = self.ref.child("Customers")
let query = ref.queryOrdered(byChild: "serviceID/status_of_service")
.queryEqual(toValue: "Open service")
query.observeSingleEvent(of: .value, with: { (snapshot) in
for child in snapshot.children {
let snap = child as! DataSnapshot
print(snap)
}
})
the output is two customer nodes
tom_smith
serviceID
status_of_service: "Open service"
another_customer
serviceID
status_of_service: "Open service"
I'm making a simple app which displays the name of each item inside this database, and when the user swipes left, they can delete the item, along with its name and quantity. When this happens, I need to delete that entire node from the database. How would I obtain their IDs to do this?
For example, when user swipes left on Apple, I need to obtain the ID KXsWXi1XE5cwdJiJQnj and delete that whole section.
Thanks in advance.
You will likely want to associate the ID of a cell to the actual cell. You can do this by creating a list of IDs and appending to that list each ID from your database. So when the user selects the second item in the list, you can access the associated ID by going to the second item in the list of IDs.
For example:
var listOfIDs = [String]() // goes in public scope of class
//Adding data from database to populate cells
for child in snapshot.children {
// Add child info to your list of info being displayed
// HERE YOU WOULD APPEND listOfIDs by this child's ID
}
Try this:-
FIRDatabase.database().reference().child("ShoppingItems").observeSingleEvent(of: .value, with: {(Snapshot) in
if let snapDict = Snapshot.value as? [String:AnyObject]{
for each in snapDict{
let key = each.key
print(key)
}
}
})
To delete:-
Delete from the local database i.e array and then call this function
FIRDatabase.database().reference().child("ShoppingItems/\(key)").removeValue()
Where key is your key for the value or cell.