EntityFramework save with constraints

Question

I have a DB that has constraints on non-nullable fields.

Let's look at just one: ModifiedDate.

The constraint defaults to getdate() when not supplied a value in an INSERT command.

My code is using Entity Framework so I craft up an entry object, create a datetime instance, set its ModifiedDate field, then execute context.SaveChanges() and it works fine.

However, if I create the object and don't set entry.ModifiedDate then context.SaveChanges() fails before the constraint could set a default value

Non-nullable field should have value. So assign default value at database level instead of entity framework. — Nilesh Khisadiya
– Nilesh Khisadiya, Commented Jun 30, 2017 at 14:38

Chris Pickford · Accepted Answer · 2017-06-30 14:41:15Z

3

In your entity class you could annotate your ModifiedDate property with the following:

[DatabaseGenerated(DatabaseGenerationOption.Computed)]
public DateTime ModifiedDate { get; set; }

From BOL: DatabaseGenerated

An important database features is the ability to have computed properties. If you're mapping your Code First classes to tables that contain computed columns, you don't want Entity Framework to try to update those columns. But you do want EF to return those values from the database after you've inserted or updated data. You can use the DatabaseGenerated annotation to flag those properties in your class along with the Computed enum.

edited Jun 30, 2017 at 14:41

answered Jun 30, 2017 at 14:39

Chris Pickford

9,0606 gold badges51 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

justiceorjustus Over a year ago

You can also do this from the .edmx designer. Select your DateTime column and go to properties and change StoreGeneratedPattern from None to Computed.

toadfromgrove Over a year ago

This worked perfectly! However, we are going with the db-first approach so is there any way EF would scaffold the models with this annotation? The reason I ask is because there are a lot of tables and each have a ModifiedDate and SysModifiedUser field.

Chris Pickford Over a year ago

@toadfromgrove Guessing you're using EF6 where default constraints aren't persisted? You could create partial classes for your entities that sets the property as a workaround.

toadfromgrove Over a year ago

@ChrisPickford Yes, I just checked and it's EF 6.1.3. In NuGet it shows 6.1.3 as the latest stable version. Is there a newer version that does take constraints into account when scaffolding?

Chris Pickford Over a year ago

I believe EF7 will do, but don't quote me on that.

Collectives™ on Stack Overflow

EntityFramework save with constraints

1 Answer 1

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related