Update ContextModelSnapshot EF Core

Question

I'm newer to EF Core, so please forgive me if there is a trivial answer.

Take this scenario....

A new web-application is being developed using the latest version of ASP.NET Core, with a code-first approach. At some point, the ContextModelSnapshot became out of sync with the database, due to deletions or source control. We cannot delete the database and recreate it.

Question: How can the snapshot be 're-synced' with the database?

Alamein

Answer 1

You can execute the command

Add-migration temporary

to create a new empty migration. Then, run

Remove-Migration temporary (or their dotnet-cli counterparts)

In recent editions of EF Core (3+), just use:

Remove-Migration (will revert the last migration)

It will create model snapshot from scratch even if the migration has already been deleted. This approach works perfectly for Ef core 2.2.0-rtm-35687

Balsa

pretty unexpected way to recreate snapshot from database, but works – Farris

This doesn't work because Add-Migration cannot be run without a migration name. – Strother

Give it a name with Add-Migration MyName The name is not important because Remove-Migration will remove the file. – Krieg

Remove-Migration takes no argument, at least in the recent releases of EF Core. – Picklock

I am quite puzzled by "It will Revert model snapshot". Did @m-artem mean "It will recreate it from scratch"? Since it was out of sync, I don't see how it could be "reverted" so I assume it's "recreated". – Sparke

Remove-Migration reverts the changes in the snapshot (EF Core 6). It's very confusing. – Neoprene

Answer 2

This is caused by merging multiple migrations from different branches + remove migration after merging. After merge snapshot is Ok, but migrations designers are not synced.

If at any point you do remove migration, snapshot is recreated from latest applied migration designer. If designer doesn't contain all previous changes, from that point snapshot is not synced. When snapshot is not synced, even if you don't have changes in entity model, on adding new migration instead of empty migration you will have migration with already applied changes (but snapshot and migration designer are OK after new migration).

So if you are sure that all changes from entities are applied, solution is to add empty migration:

1. add new migration - this will sync snapshot, migration designer will be ok for future migration removing
2. remove all commands from migration .cs file.

Grussing

Answer 3

for EF Core 8.0.1 (slight difference to existing answers)

1. Delete ApplicationDbContextModelSnapshot.cs if it present

2. Delete out of synch migration

3. Comment out most recent changes in ApplicationDbContext

4. check solution builds

5. Add-Migration temp

6. Delete temp migration file

7. then uncomment most recent changes in ApplicationDbContext and run Add-Migration ... as usual

Wimble

Answer 4

it is so simple just remove ContextModelSnapshot then add new migration

Hadsall

This is incorrect. If you delete the ContextModelSnapshot and add a new migration, then the new migration will contain ALL the instructions from the previous migrations (making the new migration redundant --and even conflicting-- to the former ones) – Sparke