| name | ef-migration |
| description | Create, review, and apply an EF Core migration safely. Use when the user wants to add a migration, change the database schema, add/modify entity properties, or asks about database changes. |
| argument-hint | [MigrationName] |
| allowed-tools | Bash(dotnet ef *), Bash(dotnet build*), Read, Grep, Glob |
EF Core Migration Procedure
Follow every step in order. Never skip the review step.
- Verify the model change first. Confirm the entity and its
IEntityTypeConfiguration<T> are updated and the solution builds:
dotnet build --nologo
- Check for pending migrations that were never applied:
dotnet ef migrations list --project src-or-Data-project. If unapplied migrations exist, ask the user whether to apply or fold changes before adding another.
- Generate the migration with a PascalCase, intent-revealing name (e.g.
AddBookRatingTable, not Update1):
dotnet ef migrations add $ARGUMENTS --project <Data project> --startup-project <Api project>
- Review the generated migration — read the new file and check for:
- Unintended column drops or renames (EF sees renames as drop+add; use
RenameColumn manually only via a new migration, never by editing)
- Missing max lengths on new string columns
- Cascade delete behavior you did not intend
- Data loss warnings emitted by the tool
- Report the review findings to the user before applying anything.
- Apply only with explicit user confirmation:
dotnet ef database update --project <Data project> --startup-project <Api project>
- Never hand-edit existing migration files or the model snapshot. To fix a bad unapplied migration:
dotnet ef migrations remove, fix the model, regenerate.
Rollback
To revert the database to a previous state: dotnet ef database update <PreviousMigrationName>, then dotnet ef migrations remove for each unapplied migration on top.
