create-migration

name	create-migration
description	Create and manage Entity Framework Core database migrations including schema changes, seed data, and rollback strategies. Use when adding or modifying EF Core entities, setting up a new DbContext, applying data seeding, running dotnet ef commands, or troubleshooting migration conflicts.

Create EF Migration

Create, review, and apply Entity Framework Core migrations safely.

Workflow

1. Make entity/model changes in code
2. Generate migration with a descriptive name
3. Review the generated migration — verify no unintended column drops or data loss
4. Apply to local database and verify
5. Commit migration files with the related entity changes

Creating Migrations

# Generate a new migration (from the project directory containing the DbContext)
dotnet ef migrations add AddInvoiceLineItems --project src/MyApp.Data --startup-project src/MyApp.Api

# Apply to local database
dotnet ef database update --project src/MyApp.Data --startup-project src/MyApp.Api

# Rollback to a previous migration
dotnet ef database update PreviousMigrationName --project src/MyApp.Data --startup-project src/MyApp.Api

# Remove the last unapplied migration
dotnet ef migrations remove --project src/MyApp.Data --startup-project src/MyApp.Api

Best Practices

• Descriptive names: AddInvoiceLineItems, RenameUserEmailToContactEmail — never Update1
• Small and focused: One schema change per migration for easier rollback
• Seed data: Use HasData() in OnModelCreating or IEntityTypeConfiguration<T>, not raw SQL in migrations
• Review before applying: Check the generated Up() and Down() methods for unintended drops or data loss
• Test locally: Always apply against a local database before committing

Checklist

• Migration has a descriptive, intention-revealing name
• Generated Up() and Down() methods reviewed for correctness
• No unintended column drops or data loss
• Migration applied successfully to local database
• Seed data uses HasData(), not raw SQL
• Migration files committed alongside entity changes