Question

I’m getting this error:

Only parameterless constructors and initializers are supported in LINQ to Entities.

When trying to run this code (found this code here and made test database to play around with):

XElement xml = new XElement("contacts",
                    from c in db.Contacts
                    orderby c.ContactId
                    select new XElement("contact",
                              new XAttribute("contactId", c.ContactId),
                              new XElement("firstName", c.FirstName),
                              new XElement("lastName", c.LastName))
                    );

where db is the auto created entities object. Any ideas on how to get this to work?

Answer 1

I believe it’s objecting to the fact that you’re using an XElement constructor that takes parameters in your “select” clause. Since XElement doesn’t have a parameterless constructor, you might need to change your code to select an anonymous type, and initialize the XElement collection after the fact.

var els = from c in db.Contacts
          orderby c.ContactID
          select new { c.ContactID, c.FirstName, c.LastName };

var xml = new XElement("contacts",
    els.ToList()
       .Select(e => new XElement("contact", 
                        new XAttribute("contactID", e.ContactID),
                        new XElement("firstName", e.FirstName),
                        new XElement("lastName", e.LastName))));

That’s untested, but hopefully gives you the idea. I’m doing the EF query first, and then calling ToList() on it so that I can select the XElement collection using Linq to Objects rather than EF.