Entity-framework – Update-Database tries to do an automatic migration even with automatic migrations disabled

entity-frameworkentity-framework-migrations

I work on a team of 4 developers using EF5, everyone working on their own local database. Up until now we've been using automatic migrations but we're nearing the point where we need to release to production so we've disabled automatic migrations and started adding explicit code-based migrations.

Here is the problem: I ran the Update-Database command after a developer created a new explicit migration and I get the following error:

Applying code-based migrations: [201209080142319_CreatedDate.LastModifiedDate.Additions].
Applying code-based migration: 201209080142319_CreatedDate.LastModifiedDate.Additions.
Applying automatic migration:    201209080142319_CreatedDate.LastModifiedDate.Additions_AutomaticMigration.
Automatic migration was not applied because it would result in data loss.

Why do I get this error even though I've disabled automatic migrations? I can fix this error by deleting the explicit migration and then re-scaffolding it (running Add-Migration). Then Update-Database runs fine and doesn't mention anything about 'Automatic migration…' Also, the code in the migration created by me when I run Add-Migration is identical to the one created by my teammate. I don't see why it would even try to do an automatic migration since AutomaticMigrationsEnabled = false;.

What am I missing here?

Best Answer

I hate to answer my own question but I encountered this problem again. A developer on my team re-enabled automatic migrations on their local machine and then created an explicit migration, which reproduced this behavior as soon as I ran it.

Entity framework will always run an automatic migration before it runs an explicit migration that has the Source property defined in its .resx file, even if AutomaticMigrationsEnabled = false. An explicit migration will only have the Source property set if it is created after an automatic migration has been run.

The upshot is that disabling automatic migrations only means that EF won't automatically upgrade your schema when it detects model changes - but it might still do an automatic migration if it needs to fill in a gap between some explicit migrations. To avoid this behavior, don't use a mixture of automatic migrations and explicit migrations.

Related Solutions

Entity-framework – EF Migrations: Rollback last applied migration

I want to add some clarification to this thread:

Update-Database -TargetMigration:"name_of_migration"

What you are doing above is saying that you want to rollback all migrations UNTIL you're left with the migration specified. Thus, if you use GET-MIGRATIONS and you find that you have A, B, C, D, and E, then using this command will rollback E and D to get you to C:

Update-Database -TargetMigration:"C"

Also, unless anyone can comment to the contrary, I noticed that you can use an ordinal value and the short -Target switch (thus, -Target is the same as -TargetMigration). If you want to rollback all migrations and start over, you can use:

Update-Database -Target:0

0, above, would rollback even the FIRST migration (this is a destructive command--be sure you know what you're doing before you use it!)--something you cannot do if you use the syntax above that requires the name of the target migration (the name of the 0th migration doesn't exist before a migration is applied!). So in that case, you have to use the 0 (ordinal) value. Likewise, if you have applied migrations A, B, C, D, and E (in that order), then the ordinal 1 should refer to A, ordinal 2 should refer to B, and so on. So to rollback to B you could use either:

Update-Database -TargetMigration:"B"

Update-Database -TargetMigration:2

Edit October 2019:

According to this related answer on a similar question, correct command is -Target for EF Core 1.1 while it is -Migration for EF Core 2.0.

Entity-framework – EF: Automatic migrations are running when disabled

Check out the answer from jjslagace here:

Update-Database tries to do an automatic migration even with automatic migrations disabled

You are building your migrations manually. My guess is entity framework wants to add something that you don't have in your migration script, or it wants to name columns differently etc. EF has a brain, and that brain is fairly simple. It's expecting things to be a certain way unless you tell it otherwise using fluent (not by manually creating/tweaking migration files). From the answer on the question above it sounds like sometimes that results in the issue you are seeing.

Long story short don't build the migration files manually. Instead run the add-migrations command. This will create the migration for you and you can see what EF is expecting to do before it's applied to your database (because sometimes it's stupid). If you need to override what EF is generating for you add a fluent mapping in your DBContext class by overriding OnModelCreating. Then just run add-migration again with the -force option. Here is a good reference for using the Fluent API to custimize EF mappings. Rinse and repeat until you get the migration you are looking for then run update-database.

Hope that helps!

Best Answer

Related Solutions

Entity-framework – EF Migrations: Rollback last applied migration

Edit October 2019:

Entity-framework – EF: Automatic migrations are running when disabled

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