EF Core 1.1 generating unique index on FK one-to-one

I’m using EF Core 1.1 and created my one-to-one relationships, an example:

EntityTypeBuilder<Account>
   .HasOne(a => a.Customer)
   .WithOne(a => a.Account)
   .HasForeignKey<Account>(a => a.CustomerId)

Now using Add-Migration on my DbContext it generates the following:

migrationBuilder.CreateIndex(
   name: "IX_Accounts_CustomerId",
   table: "Accounts",
   column: "CustomerId",
   unique: true);

Is there a way to specify in Fluent to remove the uniqueness from the index? I don’t mind the index being generated, but for my purposes it can not be unique. The reason is that these tables are auditable so there can be duplicate data (outside of the PK). Hence records can contain the same FK id if there were no changes to that FK entity (but maybe changes elsewhere in the record).

TL;DR Any way of making the index non-unique in Fluent for one-to-one FKs?

[smitpatel]

Answered on stackoverflow. http://stackoverflow.com/questions/41170325/ef-core-1-1-generating-unique-index-on-fk-one-to-one/41172323#41172323

[ishakdemir]

@ajcvickers There are some open source EF-based auditing frameworks out there that, in essence, apply the same concepts to what I just described. For example: https://www.nuget.org/packages/TrackerEnabledDbContext

However none that I’ve researched are EF Core compatible and I do need a little finer control of things hence they usually don’t work out for my use cases. But the concepts are very similar.

Really EF Core doesn’t need to do anything special for auditing. I just need that 1:1 FK to be a non-unique index. I tried a while ago to not define the 1:1 relationship for that audit dbcontext but it generated one anyway (I believe it’s called shadowing)… so I just decided to explicitly define them myself. That’s why I suggested earlier if we could turn off the uniqueness-- or maybe even the index in general-- when defining the 1:1 relationship, e.g.

EntityTypeBuilder<Account>
   .HasOne(a => a.Customer)
   .WithOne(a => a.Account)
   .HasForeignKey<Account>(a => a.CustomerId)
   .HasIndex(false)

But it would be cool if you could build an add-on to EF Core that does this auditing OOTB… I’m sure lots of people would use it 😉

thank you