How to use the default Entity Framework and default date values

Question

In my SQL Server database schema I have a data table with a date field that contains a default value of

CONVERT(VARCHAR(10), GETDATE(), 111)

which is ideal for automatically inserting the date into the new record when manually entering records in to the database.

The problem I have is that when using the Entity Framework and mapping the Date field, that the Entity Framework inserts a default value of DateTime.Min when the entity is instantiated.

I cannot map the Date field to a nullable DateTime, i.e. DateTime?, nor am I able to use either CONVERT or DateTime.Now.Today in the default value of the Entity Designer as it only accepts hard-coded constant values.

I can of course explicitly set the DateTime field in C# whenever the object is created, either explicitly in code, in the constructor of a partial class, or even during the saving changes event.

Are there any other ways of achieving what I want where the default value calculation stored in the database table is actually used instead?

Answer 1

You can use a database trigger, which, on insertion, checks if the inserted value is DateTime.MinValue (01.01.0001) and replaces it with the calculated value you desire. This MSDN article describes how to create a trigger.

A little "flaw": with this solution you would have to store the new object to the database and read it back afterwards to update your object with the calculated value.

Answer 2

The date field can be mapped to DateTime? only if the column is nullable in the database.

Answer 3

I just ran into this - I worked around it by setting the date (the field I needed auto generated) in the constructor of the Entity using a partial method. Whether this is Ideal or whether it works in all cases is yet to be seen, but it has fixed my problem so far.

Answer 4

Create a partial class for your EntityObject, add a default constructor, and set default values in it.

    public partial class YourDBObject
    {
          public YourDBObject()
          {
               this._DateField = DateTime.Now;
          }
    }