Initialize object with Firestore data within a model - ios

Question

I'm am looking for a nice an clean way to assign and get the user/author from my post object.
I could possible loop throw each Post in the posts array and get the user data from Firestore and assign it to the post property from within the viewcontroller, but what I'm looking for is like a computed property or lazy property that gets the data from Firestore and adds it to the object automatically when Post is initialized.
I don't no if it is possible or if it is the right way to do it, been struggling trying different methods with out any success.
This is my current post model - Post.swift
struct Post {
var author: User?
let authorUID: String
let content: String
init(authorUID: String, content: String) {
self.authorUID = authorUID
self.content = content
}
var dictionary: [String:Any] {
return [
"authorUID": authorUID,
"content": content
]
}
}
In my viewController I have a array of post witch get filled by data from the Firestore database - PostViewController.swift
func loadAllPosts() {
database.collection("posts").getDocuments { (querySnapshot, error) in
if let error = error {
print("Error when loading uhuus: \(error.localizedDescription)")
} else {
self.posts = querySnapshot!.documents.flatMap({Post(dictionary: $0.data())})
DispatchQueue.main.async {
self.tableview.reloadData()
}
}
}
}
This is what I was imagining my Post model would look like - Post.swift
(This code does not work and returns a "Unexpected non-void return value in void function" error)
struct Post {
private var database = Firestore.firestore()
var author: User?
let authorUID: String
let content: String
init(authorUID: String, content: String) {
self.authorUID = authorUID
self.content = content
}
var dictionary: [String:Any] {
return [
"authorUID": authorUID,
"content": content
]
}
private var setUser: User {
database.collection("users").document(authorUID).getDocument { (document, error) in
if let user = document.flatMap({ User(dictionary: $0.data()) }) {
return user
} else {
print("Document does not exist")
}
}
}
}
If you don't have a solutions but nows this is bad practice, Then I would like to know why and what would be the best way.

Answer 1

You seem to be on the right track with your second code snippet. You might consider triggering the setUser function when you init a Post as that is the point where you will have a valid authorId.
The reason you are getting that error is because you are trying to return a User in your setUser function, when what you really need to do is just update your user variable on that particular Post.
I'd suggest updating like so:
struct Post {
private var database = Firestore.firestore()
var author: User?
let authorUID: String
let content: String
init(authorUID: String, content: String) {
self.authorUID = authorUID
self.content = content
//Immediately fetch the User object here
self.setUser()
}
var dictionary: [String:Any] {
return [
"authorUID": authorUID,
"content": content
]
}
private func setUser() {
database.collection("users").document(authorUID).getDocument { (document, error) in
if let user = document.flatMap({ User(dictionary: $0.data()) }) {
//Set the user on this Post
self.author = user
} else {
print("Document does not exist")
}
}
}
}
On a somewhat unrelated note, you might want to avoid having a database reference inside each Post object. It will still work if you continue the way you have it here, but it's not the Post's job to keep track of this. It'd make more sense to have it in a separate class that is built to deal with database functions.