sql - Linq to SQL - Attribute based mapping - cannot instantiate new object with no arguments

Question

I want to extend Linq's DataContext class to implement the ORM. Currently my model looks like this:

public class Trial : DataContext
{
    public Trial(string connectionString) : base(connectionString) { }

    [Column(DbType = "System.Guid", IsPrimaryKey = true, IsDbGenerated = true, CanBeNull = false)]
    public Guid TrialID { get; set; }

    //...
}

However when I try to instantiate a new Trial object to insert it into the database I get an error complaining that Trial does not have a constructor that takes 0 arguments. When I try to create such a constructor, VS complains that DataContext does not have a constructor that takes 0 arguments.

Am I missing something here? How do I seperate the data context from the model definition?

(First time using Linq!)

Thanks in advance, Max.

Answer 1

Your data context that represents the database view should inherit from DataContext. It should expose Tables where T is the entities (rows) that you want to add. Try generating a model from the database using the designer or SQLMetal and take a closer look at the generated code to see what's going on.