Is it possible to change the location of the EF Mi

问题:

By default, the add-migration command attempts to create the migration .cs file in

• Project Root
  • Migrations

I'd like to store my migrations along with the rest of my EF-related code in the \Data folder of my project:

• Project Root
  • Data
    • Migrations

With this structure, when I execute

PM> add-migration Migration1

in the NuGet console I receive the following error:

    System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\MyProjectRoot\Migrations\201112171635110_Migration1.cs'.
   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options)
   at System.IO.StreamWriter.CreateFile(String path, Boolean append)
   at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize)
   at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding)
   at System.IO.File.InternalWriteAllText(String path, String contents, Encoding encoding)
   at System.IO.File.WriteAllText(String path, String contents)

Is it possible to specify the location on disk that the migration file should be created when executing the add-migration command?

回答1:

In the configuration class constructor add this line:

this.MigrationsDirectory = "DirOne\\DirTwo";

The namespace will continue to be set as the namespace of the configuration class itself. To change this add this line (also in the configuration constructor):

this.MigrationsNamespace = "MyApp.DirOne.DirTwo";

回答2:

Specifying the migrations folder is also possible during the invoke of the enable-migrations command (which creates the Configuration class), using the -MigrationsDirectory parameter:

enable-migrations -EnableAutomaticMigration:$false -MigrationsDirectory Migrations\CustomerDatabases -ContextTypeName FullyQualifiedContextName

The example will create a Configuration class which sets the MigrationsDirectory to the specified folder 'Migrations\CustomerDatabases' which is relative to the projects root folder.

public Configuration()
{
    AutomaticMigrationsEnabled = false;
    MigrationsDirectory = @"Migrations\CustomerDatabases";
}

See also this article which explains about a project with multiple contexts and migration folders.

By the way, if you are using multiple migrations folders and multiple contexts, please consider also to set up a name for the default schema in the OnModelCreating method of you DbContext derived class (where the Fluent-API configuration is). This will work in EF6:

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.HasDefaultSchema("CustomerDatabases");
    }

The will prefix you database tables with the schema name. This will enable you to use more than one context with a single database in a scenario where you have several groups of tables which are independent from another. (This will also create separate versions of the MigrationHistory tables, in the example above it would be CustomerDatabases.__MigrationHistory).