Problem with converting int to string in Linq to entities

Question

var items = from c in contacts
            select new ListItem
            {
                Value = c.ContactId, //Cannot implicitly convert type 'int' (ContactId) to 'string' (Value).
                Text = c.Name
            };
var items = from c in contacts
            select new ListItem
            {
                Value = c.ContactId.ToString(), //Throws exception: ToString is not supported in linq to entities.
                Text = c.Name
            };

Is there anyway I can achieve this? Note, that in VB.NET there is no problem use the first snippet it works just great, VB is flexible, im unable to get used to C#'s strictness!!!

Answer 1

Can you try:

var items = from c in contacts
        select new ListItem
        {
            Value = Convert.ToString(c.ContactId), 
            Text = c.Name
        };

Answer 2

My understanding is that you have to create a partial class to "extend" your model and add a property that is readonly that can utilize the rest of the class's properties.

public partial class Contact{

   public string ContactIdString
   {
      get{ 
            return this.ContactId.ToString();
      }
   } 
}

Then

var items = from c in contacts
select new ListItem
{
    Value = c.ContactIdString, 
    Text = c.Name
};

Answer 3

I think the best solution is:

var collection = contacts.ToDictionary(i=> i.ContactId, i=> i.Name);
IEnumerable<ListItem> listItems = from i in collection
                                  select new ListItem
                                  {
                                      Value = Key.ToString(),
                                      Text = Value
                                  };

Or do it inline:

IEnumerable<ListItem> listItems = 
    from i in contacts.ToDictionary(i=> i.ContactId, i=> i.Name)
                                  select new ListItem
                                  {
                                      Value = Key.ToString(),
                                      Text = Value
                                  };

Answer 4

With EF v4 you can use SqlFunctions.StringConvert. There is no overload for int so you need to cast to a double or a decimal. Your code ends up looking like this:

var items = from c in contacts
        select new ListItem
        {
            Value = SqlFunctions.StringConvert((double)c.ContactId),
            Text = c.Name
        };