How to return a LINQ query properly in a function?

Question

I am using LINQ/C# and trying to return the query's result from a function. What I have is below and does not work. Any suggestions? I know this should go into my Model but one step at a time. When I can get this to work I will then move to model.

Currently my Listbox in the button1_Click is only returning the table names. Example Table1.Table2.

        public IQueryable runDBQuery()
        {

            Variables obj = new Variables();
            var urlList = from SURL in db.SteamURLs
                          where obj.UserID == SURL.uID
                          select SURL;

            dataGridView1.DataSource = urlList;

            return urlList;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            var urlList = runDBQuery();

            // This doesn't work?
            listBox1.DataSource = urlList;
        }

ANSWER:

public IList<SteamURL> runDBQuery()
        {

            Variables obj = new Variables();
            var query = from SURL in db.SteamURLs
                          where obj.UserID == SURL.uID
                          select SURL;

            var urlList = query.ToList();
            dataGridView1.DataSource = urlList;

            urlList.ToList();

            return urlList;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            var urlList = runDBQuery();

            // This doesn't work?
            listBox1.DataSource = urlList;
            listBox1.DisplayMember = "itemURL";

        }

Answer 1

You are trying to tell the ListBox to be databound to an entire set of fields represented by the SteamURL entity, but the Listbox (which has only a single column that it can display) has no idea which one of the fields to display so it's just showing a default string to represent "an object is bound to this entry in the list".

you need to tell the ListBox what the DisplayMember property is.

e.g if there is a property on a SteamURL called URL (just guessing) then before this line

listBox1.DataSource = urlList;

put this:

listBox1.DisplayMember="URL";

and it should work. I second all the recommendations above by the way, do not return or bind to an IQueryable in this case - you should transform urlList using ToList() or similar first:

var query= from SURL in db.SteamURLs
                         where obj.UserID == SURL.uID
                         select SURL;
//this "materialises" the query and fetches the results back from the database. 
        var urlList= query.ToList(); 
//This means that you won't inadvertently trigger another database access by referring to urlList later on.
       dataGridView1.DataSource = urlList;
       return urlList;