It's easy I thought, just select the Property of the EntityType and set the Default Value in the Properties window to: DateTime.Now
But it's not
Defaultvalues get validated on Compile time not on Design time.
So after Rebuild you get:
Error 1 Error 54: Default value (System.DateTime.Now) is not valid for DateTime. The value must be in the form 'yyyy-MM-dd HH:mm:ss.fffZ'. C:\DataPeterGfader\ProjectsTFS\ImportantClient\Business\Entities\MyImportantModel.edmx
How to set then the default value?
Use the constructor of the Entity.
Yes I know that it's not nice to to this manually!
Example code
public partial class Transactions { public Transactions() { //HACK: To prevent this error: {"SqlDateTime overflow. Must be between 1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM."} this.LastModified = System.DateTime.Now; } }