How do I filter data from my Firebase Database? - swift

Question

How do I change the fetchAllPosts function in my networking file and in the homeviewController so that I only get posts from the database that match the UID of the user I’m following with the post.UID, so my feed is filled with posts of users I follow?
Here is the reference showing how I make a new follower in the database:
let followingRef = "following/" + (self.loggedInUserData?["uid"] as! String) + "/" + (self.otherUser?["uid"] as! String)
Here is the post structure in the Firebase database
posts
-Ke4gQKIbow10WdLYMTL (generated key)
postDate:
postId:
postPicUrl:
postText:
postTit:
type:
uid: looking to match this
Here is the current fetchAllPosts function in the networking file
func fetchAllPosts(completion: #escaping ([Post])->()) {
let postRef = self.dataBaseRef.child("posts")
postRef.observe(.value, with: { (posts) in
var resultsArray = [Post]()
for post in posts.children {
let post = Post(snapshot: post as! FIRDataSnapshot)
resultsArray.append(post)
}
completion(resultsArray)
}) { (error) in
print(error.localizedDescription)
}
}
here is the fetchAllPosts function in the homeViewController
private func fetchAllPosts(){
authService.fetchAllPosts {(posts) in
self.postsArray = posts
self.postsArray.sort(by: { (post1, post2) -> Bool in
Int(post1.postDate) > Int(post2.postDate)
})
self.tableView.reloadData()
}
}
Here is my post structure in my swift file:
struct Post {
var username: String!
var uid: String!
var postId: String!
var type: String
var postText: String
var postTit: String
var postPicUrl: String!
var postDate: NSNumber!
var ref: FIRDatabaseReference!
var key: String = ""
init(postId: String,postText: String, postTit:String, postDate:NSNumber, postPicUrl: String?, type:String, uid: String, key: String = ""){
self.postText = postText
self.postTit = postTit
self.postPicUrl = postPicUrl
self.type = type
self.uid = uid
self.postDate = postDate
self.postId = postId
}
init(snapshot: FIRDataSnapshot){
self.ref = snapshot.ref
self.key = snapshot.key
self.postId = (snapshot.value! as! NSDictionary)["postId"] as! String
self.type = (snapshot.value! as! NSDictionary)["type"] as! String
self.postPicUrl = (snapshot.value! as! NSDictionary)["postPicUrl"] as! String
self.postDate = (snapshot.value! as! NSDictionary)["postDate"] as! NSNumber
self.postTit = (snapshot.value! as! NSDictionary)["postTit"] as! String
self.uid = (snapshot.value! as! NSDictionary)["uid"] as! String
self.postText = (snapshot.value! as! NSDictionary)["postText"] as! String
}
func toAnyObject() -> [String: Any] {
return ["postId":self.postId,"type":self.type, "postPicUrl":self.postPicUrl,"postDate":self.postDate, "postTit":self.postTit,"uid": self.uid, "postText":self.postText,]
}
}

Answer 1

Did you use this;
postRef.queryOrdered(byChild: "uid").queryEqual(toValue: yourUid).observe(.value, with: {
snapshot in
if let shot = snapshot {
let post = Post(snapshot: post as! FIRDataSnapshot)
}
}
This returns data you are looking for.