Adding CreatedDate to an entity using Entity Framework 5 Code First

Question

I am trying to add a CreatedDate property to entities in my Model and am using EF5 Code First. I want this date to not be changed once set, I want it to be a UTC date. I do NOT want to use a constructor, as I have many entities in my model that I want to inherit from an abstract class containing the CreatedDate property, and I can't enforce a constructor with an interface.

I have tried different data annotations and I have attempted to write a database initializer that would pick up a specific entity type and write an alter constraint with a getdate() default value for the correct table_name and column_name, but I have not been able to write that code correctly.

Please do not refer me to the AuditDbContext - Entity Framework Auditing Context or the EntityFramework.Extended tools, as they do not do what I need here.

UPDATE

My CreatedDate is null on SaveChanges() because I am passing a ViewModel to my view, which correctly has no audit property called CreatedDate in it. And even if I passed the model to my view, I am not editing or storing the CreatedDate in the view.

I read here that I could add the [DatabaseGenerated(DatabaseGeneratedOption.Identity)] and this would tell EF to store the CreatedDate correctly after Insert and Update, but not allow it to be changed by my application: but I just get a Cannot insert explicit value for identity column in table when IDENTITY_INSERT is set to OFF error by adding this attribute.

I am about to switch to EF Model First because this simple database requirement is ridiculous to implement in Code First.

Answer 1

Here is how I did it:

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime CreatedDate{ get; set; }

in my migration's Up() method:

AddColumn("Agents", "CreatedDate", n => n.DateTime(nullable: false, defaultValueSql: "GETUTCDATE()"));