Consolidating EF migrations into new InitialCreate
I have been using EF migrations for some time now and have more than 100 migration files in my project. I would like to consolidate these into a single migration before moving forward - ie I want to replace the existing InitialCreate migration with a new version that takes all my subsequent changes into account so I can then delete all the other migration files.
I do this very easily if I am not concerned with losing all the data in the DB, but I am.
How can I achieve this whilst keeping all data intact and also retaining the ability to recreate the database from scratch (without data) by just running Update-Database (which I believe is not possible using the approach outlined by Julie Lerman)?
Answer
Consider reading this nice article from Rick Strahl : https://weblog.west-wind.com/posts/2016/jan/13/resetting-entity-framework-migrations-to-a-clean-slate
Basically the solution is not trivial and needs more than just reseting all the migrations into one because you have two scenarios that needs to fit in ONE migration class:
- Create a new database => the migration class should contain every table creation
- My database is already up to date => I need an empty migration class
Solution: The idea of this process is basically this: The database and the EF schema are up to date and just the way you want it, so we are going to remove the existing migrations and create a new initial migration.
In summary, the steps to do this are:
- Remove the _MigrationHistory table from the Database
- Remove the individual migration files in your project's Migrations folder
- Enable-Migrations in Package Manager Console
- Add-migration Initial in PMC
- Comment out the code inside of the Up method in the Initial Migration
- Update-database in PMC (does nothing but creates Migration Entry) Remove comments in the Initial method You've now essentially reset the schema to the latest version.
- once the commented out migration has been executed on the desired database, uncomment the migration code