How to bind controls without data (NULL)?

Question

Hi, I have a GridView (RadGrid) being bound with data using LINQ. In the LINQ query, I use DefaultIfEmpty because some records have empty values to a lookup table.

In the real SQL query generated by LINQ, we can see LEFT OUTER JOINs, so even if some data is not provided to reference the table, records are returned.

My problem is when the RadGrid try to bind controls (RadCombobox in my case) and there is no values.

Any idea on what to do? Or even you think there's a far more better choice to achieve this, feel free to tell me.

Thank you!