How to display data from nested firebase node in swift? - ios

Question

The following is my database design in firebase
- Sports
- MainCategory (hypothetical category name)
- SubCategory1
- K_tgbBt6Vx0-kkg7e63
- name:football
- K_tgbBt6Vx0-kkg7a99
- name:golf
- Subcategory2
- K_tgbBt6Vx0-kkgad21
- name:Snooker
- K_tgbBt6Vx0-kkg7e00
- name:Table Tennis
- MainCategory2
- SomeOtherSubCategory1
-K_tgbBt6Vx0-kkg7e00
My Aim: To get all the sports under the sports node and display them category wise(i.e MainCategory and Sub category) in a uicollectionview and allow the user to select sports of his choice.
Eg. display
Main Category1
SubCategory1
Football, Golf
SubCategory2
Table Tennis, Snooker
Main Category2
SomeOtherSubCategory1
Hockey,Tennis
The following approaches only take me one level deeper in the node
rootref.child("sports").observe(.value, with: { (snapshot) in
let mainCategory = snapshot.key
for child in snapshot.children{
print(child)
}})
rootref.child("sports").observe(.childAdded, with: { (snapshot) in
let mainCategory = snapshot.key
let mySnapshot = snapshot.value! as! NSDictionary
}) { (error) in
print(error.localizedDescription)
}
Also if there is any other way i could structure my database, kindly let me know

Answer 1

`rootref.child("sports").observe(.value, with: { (snapshot) in
//This gets your mainCategory names
let mainCategory = snapshot.key
for child in snapshot.children{
print(child)
}})
rootref.child("sports").observe(.childAdded, with: { (snapshot) in
let mainCategory = snapshot.key
let mySnapshot = snapshot.value! as! NSDictionary
}) { (error) in
print(error.localizedDescription)
}
//Now what you need to do is another snapshot to get the sub categories. It would be something like this:
rootref.child("sports").child("Sub-Category").observe(.value, with: { (snaps) in
//Same steps as you did above
})
`

Answer 2

It's cool to know that a man like you with 2.5k reps is asking such a question. I assume you know MVC, of course in the future, you'd want a reusable Service Class to handle Firebase requests and Model Class to handle the data.
Next, you should know the different ways of observing data on Firebase. There is a Single Event and Event of Type. Read the doc: https://firebase.google.com/docs/database/ios/read-and-write
In structuring your database, Firebase has a doc for that too: https://firebase.google.com/docs/database/web/structure-data
Anyway, I made a sample for you, take a look:
http://www.jsoneditoronline.org/?id=5d9e7067883a538746ace7cdd9e81ebb
I made a new structure, which I believe a better structure, of your databse using jsoneditoronline website. Avoid so much nested nodes as much as possible. See my sample, I made necessary new nodes for faster and easier fetching of data. For example, if you're going to view the link above and download the database and upload it to your Firebase Database, you'll see the structure like so:
As you can see, I have here a parent node called subcategories-sportId, which has child nodes of different subcategories and each of that subcategories, we have the ids of the sports.
Another example, if we would like to get all the sports under subcategory2, we won't be using the data inside our sport node. (see below pic) But instead, we will check the data inside the subcategories-sportid node. Get a reference to that node plus add a child node of the specific subcategory string, then fetch all the sportsIds. Enumerate the sportsIDs and lastly fetch the main data of each sports.
But if we would like to get all the subcategories and main categories of the specific sports, we can use the data inside our sport node (see the above pic)

Answer 3

let cat3 = db.child("API Questions").child("Category3").child("Name")
cat3.observe(FIRDataEventType.value, with:
{ (snapshot) in
let eventDataloc = snapshot.value as? [String: AnyObject] ?? [:]
// self.Cat3Qarray.removeAllObjects()
for (_, value) in eventDataloc
{
let studsmodel = FirebaseStructureCustVM.updateQuestionData(Questiondata: value as![String:Any])
self.Cat3Qarray.add(studsmodel)
//print(studsmodel)
}
self.tableview1.reloadData()
//print snapshot here
})

Answer 4

In the below, the "API Questions" is the "root" and the "Category1" is the "child" of that root if we want to get the "Category1" data such as MaxMarks:"20",Q:"General information",Qid:"Question 1" so you can print the snapshot like this === print("the snap of the cat1 = (snapshot)") === you will get all the data which is inside of the Category1
let cat2 = db.child("API Questions").child("Category1")
cat2.observe(FIRDataEventType.value, with:
{ (snapshot) in
let eventDataloc = snapshot.value as? [String: AnyObject] ?? [:]
for (_, value) in eventDataloc
{
let studsmodel = FirebaseStructureCustVM.updateQuestionData(Questiondata: value as![String:Any])
}
print((snapshot))
})