Firebase 在 Swift 中检索数据

Question

I'm trying to retrieve specific data from just the currently logged in user. My data in my database looks like this:

For example, I want to just grab the full_name and save it in a variable userName. Below is what I'm using to grab my data

ref.queryOrderedByChild("full_name").queryEqualToValue("userIdentifier").observeSingleEventOfType(.ChildAdded, withBlock: { snapshot in
            print(snapshot.value)
            // let userName = snapshot.value["full_name"] as! String
        })

Unfortunately, this is what my console prints.

I would appreciate any help :) Thank you!

Answer 1

It gives you that warning message indexOn because you are doing a query.

you should define the keys you will be indexing on via the .indexOn rule in your Security and Firebase Rules. While you are allowed to create these queries ad-hoc on the client, you will see greatly improved performance when using .indexOn

As you know the name you are looking for you can directly go to that node, without a query.

    let ref:FIRDatabaseReference! // your ref ie. root.child("users").child("stephenwarren001@yahoo.com")

    // only need to fetch once so use single event

    ref.observeSingleEventOfType(.Value, withBlock: { snapshot in

        if !snapshot.exists() { return }

        //print(snapshot)

        if let userName = snapshot.value["full_name"] as? String {
            print(userName)
        }
        if let email = snapshot.value["email"] as? String {
            print(email)
        }

        // can also use
        // snapshot.childSnapshotForPath("full_name").value as! String
    })

Answer 2

Swift 4

let ref = Database.database().reference(withPath: "user")
    ref.observeSingleEvent(of: .value, with: { snapshot in

        if !snapshot.exists() { return }

        print(snapshot) // Its print all values including Snap (User)

        print(snapshot.value!)

        let username = snapshot.childSnapshot(forPath: "full_name").value
        print(username!)

    })

Answer 3

{
    "rules": {
         "tbl_name": {
            ".indexOn": ["field_name1", "field_name2"]
         },
    ".read": true,
    ".write": true
    }
}

You can apply indexOn on any field. Add this json in rules security and rules tab. Hope this works for you. :)

Answer 4

It retrieves logged in user data:

let ref = FIRDatabase.database().reference(fromURL: "DATABASE_URl")
let userID = FIRAuth.auth()?.currentUser?.uid
let usersRef = ref.child("users").child(userID!).observeSingleEvent(of: .value, with: { (snapshot) in
print(snapshot)

Answer 5

let ref = Database.database().reference().child("users/stephenwarren001@yahoo.com")


    ref.observeSingleEvent(of: .value, with: { (snap : DataSnapshot)  in

        print("\(String(describing:  snap.value))")


    }) { (err: Error) in


        print("\(err.localizedDescription)")

    }

Answer 6

    var refDatabase = DatabaseReference()

    refDatabase = Database.database().reference().child("users");
 let refUserIdChild = refDatabase.child("stephenwarren001@yahoo.com")
                    
                    refUserIdChild.observeSingleEvent(of: .value, with: { snapshot in

                        if !snapshot.exists() { return }

                        print(snapshot) // Its print all values including Snap (User)

                        print(snapshot.value!)
                        

                    if let tempDic : Dictionary = snapshot.value as? Dictionary<String,Any>
                    {
                           
                            if let userName = tempDic["full_name"] as? String {
                                  self.tfName.text = userName

                              }

                            if let email = tempDic["email"] as? String {
                                    self.tfEmail.text  = email

                              }

                           
                    }


                    })