当值为null时，Entity Framework 6中的Nullable DateTime属性会在保存时引发异常

Question

I have defined a Nullable DateTime property in one of my classes:

public DateTime? ControlDate { get; set; }

When using EF 6 CodeFirst to generate the database (SQL Server 2008) from my model I get:

The problem is that when I save my instance with ControlDate=null I get this exception:

conversion of a datetime2 data type to a datetime data type
resulted in an out-of-range value

I have read multiple related posts and articles saying that this usually happens when you define a Non-nullable DateTime property and try to save it without setting a valid date before, and some people suggest setting the property as nullable in case the property value can be null (which is my particular case).

My question is: why is EF trying to set a default date when my property and column type are nullable. Null should be a valid value and should flow all the way to the database without any other conversion in between.

Here a related article: Conversion of a datetime2 data type to a datetime data type results out-of-range value

EDIT: : Here is a very similar question . very detailed explanation, in case anyone is interested.

Lessons Learned: Just wanted to clarify that after looking closer, I figured out it was an issue on my side. Right before saving my object it was being set to:

myObject.ControlDate = new DateTime()

Which, while inspected, it displayed the default incompatible date 1/1/0001 . Which is well known to cause this exception. So my conclusions:

• A model declaring a non-nullable DateTime property will result in a datetime data type in SQL Server.
• An instance of a class declaring a nullable DateTime property will be able to save to the DB as null
• It is very important to set a valid default date manually (in case <> NULL), otherwise it will set it to 1/1/0001 and throw the exception

Answer 1

据我所知，它实际上是直接映射到.NET的DateTime类型的SQL Server datetime2类型，因此您可能需要在SQL Server中更改列的类型