How to exclude one table from automatic code first migrations in the Entity Framework?

Question

I'm using the Entity Framework in the Code First mode with automatic migrations enabled. Now, I have one entity whose table should not be managed (migrated) by the EF. Is there a way of disabling automatic migrations for one specific entity (i.e. table)?

score 56 · Accepted Answer · answered Dec 04 '20 at 22:50

This is now possible in EF Core 5.0 using the ExcludeFromMigrations() method, but strangely enough you have to call the ToTable() method and then use the TableBuilder.

https://devblogs.microsoft.com/dotnet/announcing-entity-framework-core-efcore-5-0-rc1/#exclude-tables-from-migrations

public class ReportingContext : DbContext
{
    public DbSet<User> Users { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<User>().ToTable(nameof(Users), t => t.ExcludeFromMigrations());
    }
}

This method also works with EF Core 6. – Miro J. Jul 06 '22 at 22:23 — Miro J., Jul 06 '22 at 22:23

score 41 · Answer 2 · answered Aug 03 '21 at 10:42

41

Another option that worked for me in EFCore 5.0 is to use SetIsTableExcludedFromMigrations:


protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    modelBuilder.Entity<MyEntity>().Metadata.SetIsTableExcludedFromMigrations(true);
}

answered Aug 03 '21 at 10:42

FernAndr

1,448
1
14
26

1

How is your answer different than the currently most voted on? – Dejan Aug 04 '21 at 13:32
15

With this method, you don't need to know the table name, which may or may not be `nameof(Users)` – FernAndr Aug 05 '21 at 07:58

score 11 · Answer 3 · answered Apr 17 '18 at 10:50

11

My TEMPORARY solution, only for dev environments. I have a separate script that runs migration and program run does not check them. So in unexpected case I was possible to invoke Ignore<ContactView>() and run migrations with this line. When it was completed, I removed this line!

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // comment out this code after migrations are done
        modelBuilder.Ignore<ContactView>();
    }

answered Apr 17 '18 at 10:50

andrew.fox

7,435
5
52
75

1

You could use a compiler, preprocessor directive E.g: #define DEVELOPING And when set, your code block gets included #If DEVELOPING modelBuilder.Ignore(); #endif Of course, you could use the built in directive DEBUG #If DEBUG modelBuilder.Ignore(); #endif https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/preprocessor-directives/preprocessor-if – Antony Booth May 17 '19 at 23:00
@AntonyBooth - in this case, it was really a "one timer". But yeah, if project policy allows it, preprocessor directives could be a way to go. – andrew.fox May 20 '19 at 06:22

score 5 · Answer 4 · edited May 23 '17 at 12:28

5

It is possible by using another DbContext to access the table in question. Migrations are bound to one DbContext (see Is it possible to have automatic migrations for one DbContext and not for another in the same project?).

edited May 23 '17 at 12:28

Community

1
1

answered Mar 03 '14 at 19:34

Dejan

9,150
8
69
117

2Toad · Answer 5 · 2023-06-17T18:54:04.107

Not sure if this is the OP's exact scenario, but I had a table that I did not want a migration generated for. I accomplished this by using ToView instead of ToTable within the DbContext:

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Entity<MyTable>(entity => {
        // Migration will not be generated for this table
        entity.ToView("MyTable", "dbo");

        entity.Property(e => e.FooBar).HasColumnType("DECIMAL(19,9)");
    });
}

It feels a bit hacky to me, but maybe it's not -- because, after all, I'm just trying to "view" the table, not write to it...

[Tested with .NET Core EF 3.1.3]

*** update 06/17/23: the above solution is still viable if you are stuck working with EF3, but if you are using EF5+ you should use the new ExcludeFromMigrations() function: https://devblogs.microsoft.com/dotnet/announcing-entity-framework-core-efcore-5-0-rc1/#exclude-tables-from-migrations

This method has a big problem with EF 5. If you define a table as view, then if you have any foreign key to this table it won't make them! I tested the method of @Tobias and that works in EF5 — MJBZA, Apr 05 '21 at 08:32

score 2 · Answer 6 · answered Feb 26 '14 at 11:30

2

You want to use the [NotMapped] annotation on that class/entity.

answered Feb 26 '14 at 11:30

Mashton

6,037
2
25
35

3

Unfortunately, this does not work. I get an InvalidOperationException saying "The type '...' was not mapped..." when I try to execute a query on the corresponding DbSet. – Dejan Feb 26 '14 at 12:12
Ah ok, so you still want it in your model but not under the control of migrations. In that case, you'll want something like this ... http://stackoverflow.com/questions/9016709/how-to-ignore-a-table-class-in-ef-4-3-migrations – Mashton Feb 26 '14 at 14:24
exactly. However, the answer you are referring to works only if you have an existing schema and then decide that EF should take control over it. In my case, I want EF to *never* touch that particular table. The schema of that table will evolve through the time but outside EF. – Dejan Feb 26 '14 at 15:05
Time for me to bow out - that's my knowledge of EF migrations stretched beyond breaking point! Good luck. – Mashton Feb 26 '14 at 15:07

How to exclude one table from automatic code first migrations in the Entity Framework?

6 Answers6

Linked

Related