I'm trying to connect my app to an existing Application.
So i created the Entities with the Entity Framework Database First.
It create all my entities and my Context that's fine.
But when i try to run it tell me that my migrations are not up-to-date so i tried to add-migration test to see what was missing...
It's creating all the table i asked it from DataBase First...
I cant recreate those tables i just want to be able to connect to those tables...
I absolutly need to connect to those tables, i cannot create a new one and i cannot clone the database.
How can i achieve this... i didnt find any resources on the subject that goes from the start to the end of the process.
Some help would be awesome!
The Problem: You can't reset migrations with existing tables in the database as EF wants to create the tables from scratch.
What to do:
Delete existing migrations from Migrations_History table.
Delete existing migrations from the Migrations Folder.
Run add-migration Reset. This will create a migration in your Migration folder that includes creating the tables (but it will not run it so it will not error out.)
You now need to create the initial row in the MigrationHistory table so EF has a snapshot of the current state. EF will do this if you apply a migration. However, you can't apply the migration that you just made as the tables already exist in your database. So go into the Migration and comment out all the code inside the "Up" method.
Now run update-database. It will apply the Migration (while not actually changing the database) and create a snapshot row in MigrationHistory.
You have now reset your migrations and may continue with normal migrations.
Related
I did a beginner mistake and deleted a table. I had to research how to recover it and was successful in doing so. But now my migrations are not working for that table. It just stays as the initial migration but the ApplicationDBContextModelSnapshot has the information I need to migrate to that table.
I have tried doing the update-database command to the specific migration and it says it's successful but no changes were made to that table. Same with doing a small change to the entity so I can execute an add-migration. The builds were successful but no changes were made.
I guess what I'm hoping for is syncing the Model Snapshot to my database and update that recovered table to the current state.
Solved it by removing the docker volumes then ran the update database command.
Everything is synced now.
I have ASP.NET Project that have Entity Framework, it have its DbContext to map to their tables on DB.
Recently I added a model and perform a migration, but later I found that this project doesn't have any migrations, but have tables in DB.
So I created an initial migration with that new table, but is also including the other tables (because I had no previous migrations obliviously)
Since migrations are a requirement for this project and I cannot drop any table to start migration history from beginning, how can i safety perform a migration of my new table and keeping a right migration history?
I was thinking in to do something like this:
Delete the InitialMigration file that I created via dotnet ef add
Create a new InitialMigration with the current already created tables
(not sure how to do that) and somehow mark it as migrated.
Add the new model/table with another migration and update database.
Could you provide any help to achieve that?
I have reverse engineered on existing database for code first. Next i Enabled-Migrating for the context (Code based migration). When i create an initial add-migration it works fine and would apply on an empty database.
But my requirement is that i need to use the same database i used for creating the models because of the data it has.
Now the conundrum is how do i implement the code based migrations. My database does not have a migration history table. So, when i run Update-database, it tries to create the existing tables and fails.
How can i capture the current state in the migration history or instruct EF to create the migration history with the current schema as the starting point.
Do i need to turn on the automatic migration for initial setup. Please suggest.
Note: I am using EF 6.
You need to establish a baseline migration of the existing items. So the first migration you create should be:
add-migration Initial -IgnoreChanges
The ignore changes tells EF to just save a snapshot of the current database. Now any subsequent migrations will not include the existing tables (just the changes). This would allow you to continue updating your existing database since EF will see the record in __MigrationHistory or deploy to a new, empty database.
See the under the hood section here.
I have an Entity Framework 6 CF project that has a few migrations already in place.
The model is now stable and there is no need to keep the migration history that already exists.
Is there a way to reset the model and merge all migration commands into the initial migration?
As an example, the first migration adds a column while the second migration adds a unique, non-clustered index. I now want to see all these changes directly in OnModelCreating rather than in separate migrations.
Migrations have both an Up and Down. You can always Re-Scaffold your application by tearing the migrations down and then adding a new migration. The Down process does not change your model, only the changes to the database. Use Update-Database -Target:migrationTargetName or Update-Database -TargetMigration:migrationNumber.
If you want a migration which starts with no database and ends with your current model, you can tear all the migrations down with Update-Database -TargetMigration:0. It's a good idea to tear down the database and then run Update-Database as a test to verify the database changes are all in sync.
Bear in mind, if you tear your migrations down to 0 and then run an Add-Migration, you will want to look very closely at the generated scaffold, as it will likely be drastically different than the incremental changes.
Is there a way to delete an automatic migration in the migration history of a project using Entity Framework Migrations? This is a code-based EF project that's has a mix of explicit and automatic updates. There is an automatic update that deletes a table of content and isn't necessary. I'd like to be able to just remove it.
For some reason, the database it's running against doesn't have a __MigrationHistory table. (At least I don't see it in the list of tables for the databases or the list of System Tables in the database. Not sure if you have to enable viewing those somehow or not inside SSMS).
Please offer any advice you have. I'm open to whatever solution as long as I can maintain all that application's data.
I hope it is not too late.
The __MigrationHistory table is made in System Tables section on Target Database(Same as base mode Database)