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Databinding ASP.net DropDownList with Entity Framework

I am trying to bind ASP.NET DropDownList to the results of an entity structure query while maintaining tiered separation. (i.e. I don't want my UI code to contain the request details, nor do my Data Layer code to have UI dependencies.) My code in the Page_Load event handler looks like this:

        IEnumerable<Lookup> TypesLookup = Business.DocumentBO.GetDocumentTypes(_LookupTypeID);
        DocTypeDropDownList.DataSource = TypesLookup;
        DocTypeDropDownList.DataTextField = "Description";
        DocTypeDropDownList.DataValueField = "LookupID";
        DocTypeDropDownList.DataBind();

Whereas my data code looks like this (there is also an intermediate business layer, but there is no processing there yet - just a walkthrough.):

    public static IEnumerable<Lookup> GetLookups(int LookupTypeID)
    {
        using (VLFDocumentEntities context = new VLFDocumentEntities())
        {
            IEnumerable<Lookup> l = (from c in context.Lookup
                        where c.LookupTypeID == LookupTypeID
                        select c);

            return l;
        }
    }

When I hit DocTypeDropDownList.DataBind (); it throws an ObjectDisposedException with the message "DocTypeDropDownList.DataBind ();". Can anyone advise me on the best way to handle this?

Thanks, Andy

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2 answers


Don't need to separate objects from context? For example:



IEnumerable<Lookup> l = (from c in context.Lookup
                        where c.LookupTypeID == LookupTypeID
                        select c);
foreach (Lookup lookup in l)
  context.Detach(lookup);
return l;
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Why don't you just use List <>?



public static List<Lookup> GetLookups(int LookupTypeID)
{
    using (VLFDocumentEntities context = new VLFDocumentEntities())
    {
        return (from c in context.Lookup
                    where c.LookupTypeID == LookupTypeID
                    select c).ToList();
    }
}
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