LINQ Query returning result set twice

Question

I am using this query to populate a drop down list on my ASP.NET page:

using (CountriesRegionsDataContext db = new CountriesRegionsDataContext())
        {
            ddlCountry.Items.Clear();
            ddlCountry.DataSource = from c in db.CountryCodes orderby c.CountryName select c;
            ddlCountry.DataTextField = "CountryName";
            ddlCountry.DataValueField = "CountryCode1";
            ddlCountry.AppendDataBoundItems = true;
            ddlCountry.DataBind();
            ddlCountry.Items.Insert(0, new ListItem("- Select a country -", "0"));
        }

The data source is a simple SQL table which contains no duplicates. However when my page renders, the bound data is repeated twice in the drop down list control (a-za-z).

Does anyone have an idea as to what might be going on? Using distinct() doesn't seem to solve the problem (and there is no duplicate data in the table), and I tried adding ToList() to the end of my query and that doesn't seem to be fixing it either.

Any chance that code is executing twice? What happens if you comment out the last line? — rsbarro
– rsbarro, Commented Jun 21, 2013 at 18:48
If you switch "AppendDataBindItems" to false, does the problem go away? — Bill Gregg
– Bill Gregg, Commented Jun 21, 2013 at 18:49
@ElGavilan what that means is that somewhere, later on in the page's lifecycle, something is calling ddlCountry.DataBind() again, which causes the control to add the contents of the data source to the list a second time. — Adam Maras
– Adam Maras, Commented Jun 21, 2013 at 18:56
So, if DataBind is being called later on... why not just let it happen? Set AppendDataBoundItems to true and remove the call to DataBind. (Also, figure out why DataBind is being called later. That doesn't sound like expected behavior to me.) — Adam Maras
– Adam Maras, Commented Jun 21, 2013 at 19:20

Erik Schierboom · Accepted Answer · 2013-06-21 19:00:12Z

4

Shamelessly stealing Adam Maras comment and posting as an answer:

What that means is that somewhere, later on in the page's lifecycle, something is calling ddlCountry.DataBind() again, which causes the control to add the contents of the data source to the list a second time.

edited Jun 21, 2013 at 19:00

Erik Schierboom

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answered Jun 21, 2013 at 18:57

Bill Gregg

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1 Comment

Adam Maras Over a year ago

You figured out the what, I figured out the why. Yay, teamwork!

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