Question

I use to linq to sql to fill a gridview:

var results = from r in db.MyForm1_hosps
                      where r.recordId == recordId
                      orderby r.hospId
                      select new { r.hospId, r.which, r.description };

        if (results.Count() > 0)
        {
            Form_1_hosp.DataSource = results;
            Form_1_hosp.DataBind();
        }

later during OnRowDataBound, i call the following code to fill in the value of a radiobuttonlist

if (e.Row.RowType == DataControlRowType.DataRow)
        {
            RadioButtonList rbl = e.Row.FindControl("which") as RadioButtonList;
            if (rbl != null)
            {
                DataRowView rowView = (DataRowView)(e.Row.DataItem);
                LoadRadioButtonList(rowView["which"], rbl);
            }
        }

I get the following error:

Unable to cast object of type '<>f__AnonymousType1`3[System.Int32,System.Int16,System.String]' to type 'System.Data.DataRowView'.

I understand that an anonymous object cannot be cast to a datarowview, but what can I cast to in order to get the value of “which”

Answer 1

You should define a proper class to describe your data, and then you will be able to cast to this class.

// replace with proper names and types, as appropriate 
class MyData 
{
     public int HospId { get; set; }
     public string Which { get; set; }
     public string Description { get; set; }
}

Update your query’s select to utilize this class for the projection

select new MyData
{
    HospId = r.hospId, 
    Which = r.which, 
    Description = r.description 
}; 

And then use the type for the cast.

MyData obj = (MyData)(e.Row.DataItem); 
LoadRadioButtonList(obj.Which, rbl); 

There are other techniques for dealing with this, such as using dynamic and letting the runtime figure it out, or using a CastByExample<T> method (you can look it up, but I consider it faily hack-ish), but this is in my opinion the cleanest thing to do.

---

You could arguably also simply omit the projection and use the full object

select r;

At which point you would simply cast to the type of the elements in db.MyForm1_hosps, which is presumably MyForm1_hosp (you would have to verify). The counter against this approach would be if your UI container is auto-generating columns and this class contains more data than you wish to display, in which case, you would want to continue with the projection into a smaller construct.