System.ObjectDisposedException not treated in facebook windows phone app

Andy Patel 发表于 Dev

user3887722

In this line appears error: "Cannot access a disposed object".

db._fbcontacts.InsertOnSubmit(new FacebookContactsList { Name = FBName });

What can a reason of it?

There is the method where I want to write name of user's account from facebook in localdatabase

public void LoadUserInfo()
     {
         using (FacebookDataContext db = new FacebookDataContext(DBConnectionstring))
         {
             FacebookClient fb = new FacebookClient(App.AccessToken);
             fb.GetCompleted += (o, e) =>
             {
                 var result = (IDictionary<string, object>)e.GetResultData();
                 var FBName = String.Format("{0} {1}", (string)result["first_name"], (string)result["last_name"]);
                 db._fbcontacts.InsertOnSubmit(new FacebookContactsList { Name = FBName });
                 db.SubmitChanges();
             };
             fb.GetTaskAsync("me");
         }
     }

user1228

Your callback method is being called after the FacebookDataContext has been disposed.

This is the code that executes immediately

 using (FacebookDataContext db = new FacebookDataContext(DBConnectionstring))
 {
     FacebookClient fb = new FacebookClient(App.AccessToken);
     // no callback method is being executed here!  
     fb.GetTaskAsync("me");
 }

then, sometime later when GetTaskAsync completes, the following is executed:

var result = (IDictionary<string, object>)e.GetResultData();           
/*blah blah snip*/
db._fbcontacts.InsertOnSubmit(new FacebookContactsList { Name = FBName });
db.SubmitChanges();

But you can see from the first code block that, upon exiting the scope of the using statement, db has already been disposed.

Instead, you'll need to pull db out of the using block and dispose of it manually...

 public void LoadUserInfo()
 {
     FacebookDataContext db = new FacebookDataContext(DBConnectionstring);
     FacebookClient fb = new FacebookClient(App.AccessToken);
     fb.GetCompleted += (o, e) =>
     {
         try
         {
             /*blah fricken blah snipped */
             db.SubmitChanges();
         }finally{
             if(db != null) db.Dispose();
         }
     };
     fb.GetTaskAsync("me");
 }

Or you can pull the instantiation of the context inside of the event handler.

public void LoadUserInfo()
{
    FacebookClient fb = new FacebookClient(App.AccessToken);
    fb.GetCompleted += (o, e) =>
    {
        /*yadda mfing blah */
        using (FacebookDataContext db = new FacebookDataContext(DBConnectionstring))
        {
            db._fbcontacts.InsertOnSubmit(new FacebookContactsList { Name = FBName });
            db.SubmitChanges();
        }
    };
    fb.GetTaskAsync("me");
}

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