I have been pondering for the longest time in my student programmer life. I would like to know
I added the keys using autoChildId.
How to get keys from firebase database swift 2? I know how to get from Android using .getKeys()
My best friend, Google, taught me to use allKeys. However, my friendship is on the verge of in despair right now as I received the following msg that our relationship with .allKeys will always fail ( see image below). Haish...
I need this in order to show the data from Firebase Database into my tableview cos I believe this is the issue to a empty table just like how my heart is for my project. No heart.
Here is how my firebase database looks like:
Here is my code:
func findPlaceToEat(){
print("inside findPlaceToEat()")
print("Plan price level")
print(planPriceLevel)
print("End of price level")
ref = FIRDatabase.database().reference()
ref.child("places_detail").child("price_level").child(planPriceLevel).observeEventType(.ChildAdded, withBlock:{
(snapshot) in
if let dictionary = snapshot.value?.allKeys! as? [String: AnyObject]{
let PlaceObj = placeObj(place_name: dictionary["place_name"] as! String, place_type: dictionary["place_type"] as! String, price_range: dictionary["price_range"] as! String, vegan_type:dictionary["vegan_type"] as! String , website: dictionary["website"] as! String)
print("Whatever")
print(PlaceObj);
//self.tableView.reloadData()
}
}, withCancelBlock: nil)
}
to get key from snapshot
snapshot.key
I got a workaround for my project, everyone please pray that my lecturer don't see this. :
What I did was inside the save button I retrieve the value from database and then save it back into Firebase Database.
ref = FIRDatabase.database().reference()
ref.child("hello").child("google! I need a part time job").child(planPriceLevel).observeEventType(FIRDataEventType.ChildAdded, withBlock:{
(snapshot: FIRDataSnapshot) in
if let dictionary = snapshot.value as? [String: AnyObject]{
let getPlaceObj = placeObj()
getPlaceObj.setValuesForKeysWithDictionary(dictionary)
self.PlaceObj.append(getPlaceObj)
print("Name " ,getPlaceObj.place_name)
}
let place_name = snapshot.value?.objectForKey("place_name") as! String
let place_type = snapshot.value?.objectForKey("place_type") as! String
let price_range = snapshot.value?.objectForKey("price_range") as! String
let vegan_type = snapshot.value?.objectForKey("vegan_type") as! String
let website = snapshot.value?.objectForKey("website") as! String
print(place_name, place_type, price_range, vegan_type, website)
let savePlan : [String: AnyObject] = ["place_name":place_name, "place_type":place_type, "price_range":price_range, "vegan_type":vegan_type, "website":website]
self.ref.child("can you place hire me as your intern? I am from Singapore!!!").child(self.user!.uid).childByAutoId().setValue(savePlan)
}, withCancelBlock: nil)
You need to define query orderbykey like bellow:
this.afd.list('/yourItems/', {query:{orderByKey :true}}).subscribe((elements) => {
elements.map(element=>{
console.log(element.$key);
})
});
Related
I am able to fetch all users but I want need user ID specific data.
For example you can see here are lots of users are registered but I need details only for 3 nodes:
323QGP6qryTWs7EnnXRX1stgocP2
iy5ssz0ALphtgViALEOG0N4TeGd2
OlA0rhAVfsNvixe8KEsUmdCfuN42
Please help to get these records.
Thanks.
let ref = Database.database().reference().child("users").observeSingleEvent(of: .value, with : { snapshot in {
if snapshot is NSNull{
//handles errors
}
else{
let dict = snapshot.value as? NSDictionary{
let firstDict = dict["323QGP6qryTWs7EnnXRX1stgocP2"] as? NSDictionary
let secondDict = dict["iy5ssz0ALphtgViALEOG0N4TeGd2"] as? NSDictionary
let thirdDict = dict["OlA0rhAVfsNvixe8KEsUmdCfuN42"] as? NSDictionary
//Then to gather whichever node you want inside these users:
let requestedNode = THEDICTIONARYYOUARELOOKINGAT["THE_NAME_OF_THE_NODE"] as? String //String, Int, Dictionary, array, boolean, ect.
}
}
})
I have a small dataset in Firebase database, but unfortunately, I can't get read value from list correctly. Here is the structure of the database.
I just need to get the value of day and reference it to var. Thanks in advance.
var collnum = ""
ref = Database.database().reference()
let collid = ref.child("collid").child("day")
collid.observeSingleEvent(of : .value, with : {(Snapshot) in
print(Snapshot)
if let snapDate = Snapshot.value as? String{
collnum = snapDate
print(snapDate)
}
})
let database = FIRDatabase.database().reference()
database.child("collid").queryOrderedByKey().observe(.value, with:
{
if let value = snapshot.value as? [String: AnyObject]
{
let ui = value["day"] as! String
print(ui)
}
}
You can do something like this to read the data. This will read the data from the database and put into an array, allowing you to read the data.
My data structure is something like the following:
restaurant_owners
|
|owner_id (a unique ID)
|
|restaurant_name
|email
restaurant_menus
|
|restaurant_name
|
|dish_type (drinks, appetizer, etc...)
|
|dish_id (a unique ID)
|
|name
|
|price
The idea of the app is basically to allow "restaurant_owners" to login and manage the menu of their respective restaurant. However I am having problems with the following code: (note that the fetchDish function is called in viewDidLoad)
func fetchDish() {
var restaurantName: String?
let uid = FIRAuth.auth()?.currentUser?.uid
//first time referencing database
FIRDatabase.database().reference().child("owners").child(uid!).observeSingleEvent(of: .value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
DispatchQueue.main.async{
restaurantName = dictionary["name"] as? String
print(restaurantName!)
}
}
})
//second time referencing database
FIRDatabase.database().reference().child("restaurants").child(restaurantName!).child("appetizer").observe(.childAdded, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let dish = Dish()
dish.setValuesForKeys(dictionary)
self.dishes.append(dish)
DispatchQueue.main.async {
self.tableview.reloadData()
}
}
}, withCancel: nil)
}
What I am trying to do is to retrieve the the name of the restaurant for the current logged in user and store it in the variable "restaurantName". Then when I am referencing the database for the second time I can use this variable inside of .child (e.g.: .child(restaurantName)).
However, when I run this, I get an error saying that the restaurantName (in the database reference) is of value nil. I tried putting in some breakpoints and it seems like the first line of the second database reference is operated before whatever is "within" the first database reference, so basically restaurantName is called before any value is stored in it.
Why is this occurring? How do I work around this problem? Also, what are the best practices to achieve this if I'm doing it completely wrong?
NoSQL is very new to me and I have completely no idea how I should design my data structure. Thanks for the help in advance and please let me know if you need any other information.
UPDATE:
The problem was solved by changing my data structure to what Jay has suggested. The following code is what worked for me: (modified Jay's code a bit)
func fetchOwner() {
let uid = FIRAuth.auth()?.currentUser?.uid
let ownersRef = FIRDatabase.database().reference().child("owners")
ownersRef.child(uid!).observeSingleEvent(of: .value, with: { snapshot in
if let dict = snapshot.value as? [String: AnyObject] {
let restaurantID = dict["restaurantID"] as! String
self.fetchRestaurant(restaurantID: restaurantID)
}
}, withCancel: nil)
}
func fetchRestaurant(restaurantID: String) {
let restaurantsRef = FIRDatabase.database().reference().child("restaurants")
restaurantsRef.child(restaurantID).child("menu").observe(.childAdded, with: { snapshot in
if let dictionary = snapshot.value as? [String: AnyObject] {
let dish = Dish()
dish.setValuesForKeys(dictionary)
self.dishes.append(dish)
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
}, withCancel: nil)
}
A couple of things:
Firebase is Asynchronous and you have to account for that in your code. As it is in the post, the second Firebase function may execute before the first Firebase function has successfully returned data i.e. restaurantName may be nil when the second call happens.
You should nest your calls (in this use case) to ensure data is valid before working with it. Like this.. and keep reading
let ownersRef = rootRef.child("owners")
let restaurantRef = rootRef.child("restaurants")
func viewDidLoad() {
fetchOwner("owner uid")
}
func fetchOwner(ownerUid: String) {
var restaurantName: String?
let uid = FIRAuth.auth()?.currentUser?.uid
ownserRef.child(ownerUid).observeSingleEvent(of: .value, with: { snapshot in
if let dict = snapshot.value as? [String: AnyObject] {
restaurantId = dict["restaurant_id"] as? String
fetchRestaurant(restaurantId)
}
}
})
}
func fetchRestaurant(restaurantId: String) {
restaurantRef.child(restaurantId).observeSingleEvent(of: .value, with: { snapshot in
if let dict = snapshot.value as? [String: AnyObject] {
let restaurantName = dict["name"] as! String
let menuDict = dict["menu"] as! [String:Any]
self.dataSourceArray.append(menuDict)
menuTableView.reloadData()
}
}
}
Most importantly, it's almost always best practice to disassociate your key names from the data it contains. In this case, you're using the restaurant name as the key. What if the restaurant name changes or is updated? You can't change a key! The only option is to delete it and re-write it.... and... every node in the database that refers to it.
A better options it to leverage childByAutoId and let Firebase name the nodes for you and keep a child that has the relevant data.
restaurants
-Yii9sjs9s9k9ksd
name: "Bobs Big Burger Barn"
owner: -Y88jsjjdooijisad
menu:
-y8u8jh8jajsd
name: "Belly Buster Burger"
type: "burger"
price: "$1M"
-j8u89joskoko
name: "Black and Blue Burger"
type: "burger"
price: "$9.95"
As you can see, I leveraged childByAutoId to create the key for this restaurant, as well as the items on the menu. I also referenced the owner's uid in the owner node.
In this case, If the Belly Buster Burger changes to the Waist Slimming Burger, we can make one change and it's done and anything that references it is also updated. Same thing with the owner, if the owner changes, then just change the owner uid.
If the restaurant name changes to Tony's Taco Tavern, just change the child node and it's done.
Hope that helps!
edit: Answer to a comment:
To get the string (i.e. the 'key' of a key:value pair) immediately created by .childByAutoId()
let testRef = ref.child("test").childByAutoId()
let key = testRef.key
print(key)
I followed a tutorial to get a timeline going. In the tutorial he uses .Value when retrieving data from Firebase. I later learned that it isn't very efficient because it re-downloads everything whenever a post is added. This causes all user's timelines to flash and auto-scroll.
I'm trying to convert this to use .childAdded but can't figure out how to get it to work. This is the current code:
DataService.ds.REF_POSTS.child("\(self.loggedInUser!.uid)").observeEventType(.Value, withBlock: { postDictionary in
if postDictionary.exists() {
if let snapshots = postDictionary.children.allObjects as? [FIRDataSnapshot] {
self.posts = []
for snap in snapshots {
if let postDict = snap.value as? NSDictionary {
for(name, value) in postDict {
let interval = postDict.objectForKey("timePosted") as! Double
let formattedDate = NSDate(timeIntervalSince1970: interval)
let timeAgo = self.getDate(formattedDate)
if name as! String == "postedBy" {
DataService.ds.REF_USERS.child(value as! String).observeSingleEventOfType(.Value, withBlock: { (userDictionary) in
let userDict = userDictionary.value as! NSDictionary
let username = userDict.objectForKey("username")!
let profileThumbUrl = userDict.objectForKey("profileThumbUrl")!
let key = snap.key
let post = Post(postKey: key, dictionary: postDict, username: username as! String, profileThumbUrl: profileThumbUrl as! String, timeAgo: timeAgo)
self.posts.append(post)
self.collectionView?.reloadData()
})
}
}
}
}
}
}
})
The 2nd Firebase call is just grabbing user info for the user thumbnail and username. When I change .Value at the top to .ChildAdded, nothing shows up on the timeline. I have tried messing around with filetypes etc. and can't get it to work.
Update
Okay so after reading another Firebase question on here it looks like .ChildAdded gets just the child added. I was thinking it got the same data, just that the whole thing would run when a child was added.
So it looks like I'm going to have to change the loops here and run a loop adding each child added one by one. Going to redo the whole thing and will post the difference when I finish it if I can get it working.
I'm new to firebase and I have such structure of my firebase project
I want to get all objects, that "Interested" value is equal to "men"
I wrote such code, to get all object sorted by interes value:
let thisUserRef = URL_BASE.childByAppendingPath("profile")
thisUserRef.queryOrderedByChild("Interest")
.observeEventType(.Value, withBlock: { snapshot in
if let UserInterest = snapshot.value!["Interest"] as? String {
print (snapshot.key)
}
}
But I receive nil.
you need to loop through all the key-value profiles
if let allProfiles = snapshot.value as? [String:AnyObject] {
for (_,profile) in allProfiles {
print(profile);
let userInterest = profile["Interest"]
}
}
Here _ is the key that is in the format KYXA-random string and profile will be the element for that key.
Edit:
There is querying for child values as per the docs.
Try thisUserRef.queryOrderedByChild("Interest").equalTo("men") and then using the inner loop that i specified in the answer
This is a basic query in Firebase. (Updated for Swift 3, Firebase 4)
let profileRef = self.ref.child("profile")
profileRef.queryOrdered(byChild: "Interest").queryEqual(toValue: "men")
profileRef.observeSingleEvent(of: .value, with: { snapshot in
for child in snapshot.children {
let dict = child as! [String: Any]
let name = dict["Name"] as! String
print(name)
}
})
The legacy documentation from Firebase really outlines how to work with queries: find it here
Legacy Firebase Queries
The new documentation is pretty thin.
Oh, just to point out the variable; thisUserNode should probably be profileRef as that's what you are actually query'ing.