Ran Enable-Migrations. Had a bit of trouble due to connection strings and which app.config was getting used, but eventually got it. However, this MSDN page says that this should have automatically generated the first migration to get me to the point I'm already at. It didn't.
Ran Add-Migration InitialSchema to accomplish what wasn't automatically done in step 1. This worked.
In fact the enable-migrations
command creates an initial migration only if your database has already been created with Code-First before in which case the database contains a __MigrationHistory
table. If this table does not exist (which is the case when you have an existing database that never has been created before with Code-First) enable-migrations
only creates the Configuration
class. You have to call add-migration
manually then to create the first migration class. So, the behaviour you have seen is expected.
Generally the procedure to prepare an existing database for migrations is the following if you are using EF 5:
Call
enable-migrations
in package manager console. AMigrations
folder in your project and aConfiguration
class will be created.Open the
Configuration
class and setAutomaticMigrationsEnabled = false
in the constructor (if it isn't already by default).In package manager console call
add-migration -IgnoreChanges InitialSchema
"InitialSchema" is only an example name. You can name it like you want. A
<Timestamp>_InitialSchema
class will be created that derives fromDbMigration
. TheUp
andDown
methods in this class are empty due to the-IgnoreChanges
flag. Without this flag the class would contain a migration to add your whole model to the database which is not what you want since the existing database already contains the database schema.Run
update-database
in the package manager console. Because theUp
method is empty this update does nothing with your existing schema except it creates the__MigrationHistory
table (as a system table in your database) and adds the first record to this table that contains a model hash of your current EF model.Optional last step: If you prefer to work with automatic migrations open the
Configuration
class and setAutomaticMigrationsEnabled = true
in the constructor. If you want to proceed with code-based migrations leave the flagfalse
.
At this point you can start to make changes to your model. Everytime you create a new migration with add-migration
it will be based on your model before the modification and the migration class will only contain the necessary schema changes.