Question

I have a WCF/REST web service that I’m considering using Linq to SQL to return database info from.

It’s easy enough to do basic queries against tables and return rows, for example:

    [WebGet(UriTemplate = "")]
    public List<User> GetUsers()
    {
        List<User> ret = new List<User>(); ;
        using (MyDataContext context = new MyDataContext())
        {
            var userResults = from u in context.Users select u;
            ret = userResults.ToList<User>();
        }

        return ret;
    }

But what if I want to return data from multiple tables or that doesn’t exactly match the schema of the table? I can’t figure out how to return the results from this query, for example:

 var userResults = from u in context.Users
   select new  { u.userID, u.userName, u.userType, 
                 u.Person.personFirstname, u.Person.personLastname };

Obviously the resulting rowset doesn’t adhere to the “User” schema, so I can’t just convert to a list of User objects.

I tried making a new entity in my object model that related to the result set, but it doesn’t want to do the conversion.

What am I missing?

Edit: related question: what about results returned from stored procedures? Same issue, what’s the best way to package them up for returning via the service?

Answer 1

You can create a Complex Type and instead of returning Anonymous object you return the Complex Type. When you map stored procedures using function import, you have a option to automatically create a complex type.

Create a custom class with the properties that you need:

public class MyTimesheet
{
    public int Id { get; set; }
    public string Data { get; set; }
}

Then create it from your Linq query:

using (linkDataContext link = new linkDataContext())
{
    var data = (from t in link.TimesheetDetails
               select new MyTimesheet
               {
                   Id = t.Id,
                   Data = t.EmployeeId.ToString()
               }).ToList();
}