Fluent configuration for base entity in Entity Framework

Question

I have the following BaseEntity

public class BaseEntity
{
    public BaseEntity()
    {
        DateCreated = DateTime.UtcNow;
        DateModified = DateTime.UtcNow;
    }

    public DateTime DateCreated { get; set; }
    public DateTime DateModified { get; set; }

    [MaxLength(36)]
    public string CreateUserId { get; set; }

    [MaxLength(36)]
    public string ModifyUserId { get; set; }
}

All my other entities derive from it. Now I'd like to use fluent configuration instead of the DataAnnotations. Do I really have to configure the MaxLength of the two string properties in every single DbModelBuilder configuration?

haim770 · Accepted Answer · 2015-03-23 12:41:25Z

7

+50

Do I really have to configure the MaxLength of the two string properties in every single DbModelBuilder configuration?

No. You can configure base type validations and EF will apply them on derived types. For example:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<BaseEntity>().Property(x => x.CreateUserId).HasMaxLength(36);
    modelBuilder.Entity<BaseEntity>().Property(x => x.ModifyUserId).HasMaxLength(36);

    base.OnModelCreating(modelBuilder);
}

Update (as per your comment):

You can use the (rather new) Properties() method to define mapping and validations based on property names rather than on entity types.

For example:

modelBuilder.Properties().Where(x => x.Name == "CreateUserId").Configure(x => x.HasMaxLength(36));
modelBuilder.Properties().Where(x => x.Name == "ModifyUserId").Configure(x => x.HasMaxLength(36));

See MSDN

edited Mar 23, 2015 at 12:41

answered Mar 19, 2015 at 10:00

haim770

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8 Comments

Sandro Over a year ago

Yes, but I want to get rid of the DataAnnotation

Sandro Over a year ago

Now I get an Exception that BaseEntity has no key defined.

haim770 Over a year ago

@Sandro, See my revision. I added Ignore<BaseEntity>(). Assuming you do have keys defined for your derived types, it should work just fine.

Sandro Over a year ago

Now I'm back to varchar(max) for these fields because BaseEntity is ignored on model creation

haim770 Over a year ago

If you'll go C# 6, you'll be able to avoid the "magic strings" using the nameof operator.

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