Swift + Parse.com : how to fetch user relation using a join table

Question

I have an app like instagram where i have to make relationship between users. For that i decided to use the join table method. It'' s just a table named "Activity" where i created rows "fromUser", "toUser" and a row for the activity type "type" which in this case is set to "followingAction".

Here how i set up the table :

    var activity = PFObject(className:"Activity")

        let currentUser = PFUser.currentUser()

        let follow : String = "followingAction"

        activity.setObject(currentUser, forKey: "fromUser")
        activity.setObject(user, forKey: "toUser") // user is a another PFUser in my app

        activity.setObject(follow, forKey: "type")

        activity.saveEventually()

Ok, now i want to fetch all users that i m currently following (currentUser) and display them in a tableView

Following the doc https://parse.com/docs/relations_guide#manytomany-jointables

i made this but it only give me an array of users which only contain the user objectId, i can't have the email, name which are set up in the regular User table :

       func loadUser () {

    followingUserList.removeAllObjects()

    let findUserObjectId =       PFQuery(className: "Activity")
    findUserObjectId.whereKey("fromUser", equalTo: userPassed)
    findUserObjectId.whereKey("type", equalTo: "followingAction")


    findUserObjectId.findObjectsInBackgroundWithBlock { (objects:[AnyObject]!, error:NSError!) -> Void in
        if error == nil  {
            // The find succeeded.
            println("succesfully loaded the fromUser  in Activity class")
            // Do something with the found objects
            for object  in objects   {

                let user : PFUser = object["toUser"] as PFUser



                        self.followingUserList.addObject(user)
                        println("User added to following user list : \(user)")
                        println("followingUserlist = \(self.followingUserList)")

                        self.tableView.reloadData()


            } } else {
            // Log details of the failure
            println("error loadind user ")
            println(error)
        }
    }
}

if i print the followingUserList which is the array where i put the fetched users, here is what i have :

followingUserlist = (
"<PFUser: 0x7d9b93c0, objectId: DQJihBpW5E, localId: (null)> {\n}"
)

When i make a regular query (PFUser.query()) for the regular User table, i have more detail :

ex :

   <PFUser: 0x7db5af80, objectId: niwftRrB5x, localId: (null)> {
backgroundImage = "<PFFile: 0x7db5f080>";
email = "[email protected]";
emailVerified = 0;
profileImage = "<PFFile: 0x7db62910>";
username = kiki;
 }

Here we can see i have the complete PFUser with it email, username etc etc.

Because the "fromRow" in my "Activity" table is a pointer to my regular User table, why the fetched result in my loadUser() method isn't complete ?

jmcastel · Accepted Answer · 2014-11-05 14:56:10Z

1

Ok i finally found the solution, i just used the getObjectInBackgroundWithId method like this :

   func loadUser () {

    followingUserList.removeAllObjects()

    let findUserObjectId =       PFQuery(className: "Activity")
    findUserObjectId.whereKey("fromUser", equalTo: userPassed)
    findUserObjectId.whereKey("type", equalTo: "followingAction")


    findUserObjectId.findObjectsInBackgroundWithBlock { (objects:[AnyObject]!, error:NSError!) -> Void in
        if error == nil  {
            // The find succeeded.
            println("succesfully loaded the fromUser  in Activity class")
            // Do something with the found objects
            for object  in objects   {

                let user : PFUser = object["toUser"] as PFUser

                let queryUsers = PFUser.query()
                queryUsers.getObjectInBackgroundWithId(user.objectId, block: { (userGet :PFObject!,error : NSError!) -> Void in
                    self.followingUserList.addObject(userGet)
                    self.tableView.reloadData()

                })


            } } else {
            // Log details of the failure
            println("error loadind user ")
            println(error)
        }
    }
}

answered Nov 5, 2014 at 14:56

jmcastel

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1 Comment

kareem Over a year ago

is "followingUserList" an array you initialized some where in your code?

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