BackendlessCollection to NSData

General
1

Hello.

I’ve been trying to parse the JSON data retrieved by the server with some user information.

I’ve successfully queried the server with a dataQuery with the specific whereClause, and it returned the required data in JSON format.

As it goes, I’ve been trying to parse that data from BackendlessCollection to NSData so I can use the NSJSON.

My code goes like the following:


let email: String = "test@gmail.com"
let query = BackendlessDataQuery()
query.whereClause = "email = '\(email)'"


let dataStore = Backendless().persistenceService.of(BackendlessUser.ofClass())
dataStore.find(query, response: { (collection) -> Void in
    print("User information found: \(collection)")
    do {
        let data = collection as! NSData
        let json = try NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments)
        if let objectId = json["objectId"] as! String? {
            print("objectId -> \(objectId)")
        }
        
    } catch {
        print("CATCH ERROR")
    }
    
    }) { (fault) -> Void in
        print("an error was found: \(fault)")

}
But in this case Xcode is prompting that the casting of BackendlessCollection to NSData will always fail.

How can we handle properly the returned data from the backend?

King regards,
-IC

2

Ivan,

When you run this code:

let dataStore = Backendless().persistenceService.of(BackendlessUser.ofClass())
dataStore.find(query, response: { (collection) -> Void in

The “collection” object you get back is an instance of BackendlessCollection which already contains objects of the type specified here: Backendless().persistenceService.of( YOUR-CLASS-TYPE )

This means in your case the data you get back are already BackendlessUser objects. You do not need to do any JSON manipulations at all - just use the objects you got back in the collection.

Hope this helps.

Mark

3

Ohh… How did I miss that! I miss-read the documentation.
I really thought the data was retrieved as a JSON regular doc.

I’ll do as you said.

Thanks for the reply Mark.

Cheers.

4

Thanks.

Now I have another doubt.
After returning the filled collection from the backend , how can I access a single instance/property of it?

The users collection returns all the default users properties of the backend, plus the ones that I’ve manually added, but I can’t figure out how to get them out.

For example, the collection is printed like this:

collection: [<BackendlessUser> {

 
 "___class" = Users; 
 
 "__meta" = "{\"relationRemovalIds\":{},\"selectedProperties\":[\"password\",\"created\",\"name\",\"___class\",\"ownerId\",\"updated\",\"email\",\"objectId\"],\"relatedObjects\":{}}"; 
 
 created = "2016-01-30 01:22:56 +0000"; 
 
 email = "email@email.com"; 
 
 lastLogin = "2016-02-18 22:34:30 +0000"; 
 
 name = ""; 
 
 objectId = "FULL-ID"; 
 
 ownerId = "&lt;null&gt;"; 
 
 password = "&lt;null&gt;"; 
 
 updated = "&lt;null&gt;"; 
 
 userStatus = ENABLED; 
 
}]

How can I access the name instance , or the lastLogin?

I’ve tried the collection.valueForKey(“lastLogin”) , but I don’t know if it’s through this path

Thanks in advance

5

use the “getProperty” method on the BackendlessUser object.

6

Thanks.

Everything is solved now.
Amazing support man.

7

Looking forward to seeing your app!! ))