Migrations

Implementation details for EF Core migrations. Use when changing MigrationsSqlGenerator, model diffing, migration operations, HistoryRepository, the Migrator or related classes.

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Migrations

Pipeline

Add migration: MigrationsScaffolder.ScaffoldMigration()MigrationsModelDiffer.GetDifferences() → list of MigrationOperationCSharpMigrationsGenerator and CSharpSnapshotGenerator produce Up/Down/Snapshot code

Apply migration: Migrator.MigrateAsync() → reads __EFMigrationsHistory → per pending: MigrationsSqlGenerator.Generate(operations)MigrationCommandExecutor executes

Model Snapshot

  • Model snapshots use typeof(Dictionary<string, object>) (property bag format), not the actual CLR type. When examining the ClrType in a snapshot, don't assume it matches the real entity type.
  • SnapshotModelProcessor.Process() is used at design-time to fixup older model snapshots for backward compatibility.

Testing

Migration operation tests: test/EFCore.Relational.Tests/Migrations/. Functional tests: test/EFCore.{Provider}.FunctionalTests/Migrations/. Model differ tests: test/EFCore.Relational.Tests/Migrations/Internal/MigrationsModelDifferTest*.cs.

dotnet/efcore/tree/main/.agents/skills/migrations commit 96e5223a20

Frequently asked questions

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