Name: ef-migration
Author: yoozek

Prompt file imported from yoozek/yoozek-claude-code (.claude/commands/dotnet/ef-migration.md). Fill in {{arguments}} before use. Copyright stays with the author.

Create and manage Entity Framework Core migrations following .NET 10 best practices.

Migration Request

Entity Framework Core Migration Workflow

1. Creating a Migration

# Create a new migration
dotnet ef migrations add AddUserTable

# With specific DbContext if multiple exist
dotnet ef migrations add AddUserTable --context ApplicationDbContext

# With specific project and startup project
dotnet ef migrations add AddUserTable --project src/YourApp.Data --startup-project src/YourApp.Api

2. Reviewing the Migration

Generated migration files in Migrations/ folder:

[Timestamp]_AddUserTable.cs - The migration class
[Timestamp]_AddUserTable.Designer.cs - Snapshot metadata
ApplicationDbContextModelSnapshot.cs - Current model snapshot

Example Migration

using Microsoft.EntityFrameworkCore.Migrations;

public partial class AddUserTable : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.CreateTable(
            name: "Users",
            columns: table => new
            {
                Id = table.Column<int>(nullable: false)
                    .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
                Name = table.Column<string>(maxLength: 100, nullable: false),
                Email = table.Column<string>(maxLength: 255, nullable: false),
                CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false)
            },
            constraints: table =>
            {
                table.PrimaryKey("PK_Users", x => x.Id);
            });

        migrationBuilder.CreateIndex(
            name: "IX_Users_Email",
            table: "Users",
            column: "Email",
            unique: true);
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropTable(name: "Users");
    }
}

3. Applying Migrations

# Apply all pending migrations to database
dotnet ef database update

# Apply to specific migration
dotnet ef database update AddUserTable

# Rollback to previous migration
dotnet ef database update PreviousMigrationName

# Rollback all migrations
dotnet ef database update 0

# Apply to specific environment
dotnet ef database update --environment Production

4. Managing Migrations

# List all migrations
dotnet ef migrations list

# Remove last migration (if not applied)
dotnet ef migrations remove

# Generate SQL script from migrations
dotnet ef migrations script

# Generate SQL for specific migration range
dotnet ef migrations script AddUserTable AddOrderTable

# Generate idempotent script (safe to run multiple times)
dotnet ef migrations script --idempotent

# Output SQL to file
dotnet ef migrations script --output migrations.sql

5. Database Operations

# Drop the database (careful!)
dotnet ef database drop

# Drop and recreate database
dotnet ef database drop --force
dotnet ef database update

# Get connection string information
dotnet ef dbcontext info

# Scaffold DbContext from existing PostgreSQL database (reverse engineer)
dotnet ef dbcontext scaffold "Host=localhost;Database=MyDb;Username=postgres;Password=..." Npgsql.EntityFrameworkCore.PostgreSQL --output-dir Models

Common Migration Scenarios

Adding a Column

// Model change
public class User
{
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
    public string Email { get; set; } = string.Empty;
    public string PhoneNumber { get; set; } = string.Empty; // New column
}

// Generated migration
migrationBuilder.AddColumn<string>(
    name: "PhoneNumber",
    table: "Users",
    maxLength: 20,
    nullable: false,
    defaultValue: "");

Renaming a Column

// Migration (manual edit required)
migrationBuilder.RenameColumn(
    name: "Email",
    table: "Users",
    newName: "EmailAddress");

Adding an Index

migrationBuilder.CreateIndex(
    name: "IX_Users_Email",
    table: "Users",
    column: "Email",
    unique: true);

Adding a Foreign Key

migrationBuilder.CreateIndex(
    name: "IX_Orders_UserId",
    table: "Orders",
    column: "UserId");

migrationBuilder.AddForeignKey(
    name: "FK_Orders_Users_UserId",
    table: "Orders",
    column: "UserId",
    principalTable: "Users",
    principalColumn: "Id",
    onDelete: ReferentialAction.Cascade);

Seeding Data

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.InsertData(
        table: "Users",
        columns: new[] { "Id", "Name", "Email", "CreatedAt" },
        values: new object[] { 1, "Admin", "admin@example.com", DateTime.UtcNow });
}

Best Practices

Migration Naming

Use descriptive names: AddUserEmailIndex, AddOrderTable
Follow pattern: [Action][Entity][Detail]
Avoid generic names like Update1, Changes

Before Creating Migration

Review model changes carefully
Ensure DbContext is configured correctly
Test locally before applying to production

Reviewing Migrations

Always review generated migration code
Customize Up/Down methods if needed
Add data migration logic for complex changes
Consider backward compatibility

Production Migrations

Generate SQL script: dotnet ef migrations script --idempotent
Review SQL before applying
Have rollback plan ready
Backup database before applying
Apply during maintenance window for major changes

Data Migrations

protected override void Up(MigrationBuilder migrationBuilder)
{
    // Schema change
    migrationBuilder.AddColumn<string>(
        name: "FullName",
        table: "Users",
        nullable: true);

    // Data migration
    migrationBuilder.Sql(@"
        UPDATE Users
        SET FullName = CONCAT(FirstName, ' ', LastName)
        WHERE FullName IS NULL
    ");

    // Make required after data migration
    migrationBuilder.AlterColumn<string>(
        name: "FullName",
        table: "Users",
        nullable: false);
}

Multiple DbContexts

# Specify context
dotnet ef migrations add MigrationName --context IdentityDbContext
dotnet ef database update --context IdentityDbContext

Separate Migrations Assembly

services.AddDbContext<ApplicationDbContext>(options =>
    options.UseNpgsql(
        connectionString,
        b => b.MigrationsAssembly("YourApp.Data")));

appsettings.json Connection String

{
  "ConnectionStrings": {
    "DefaultConnection": "Host=localhost;Database=myapp;Username=postgres;Password=yourpassword"
  }
}

Troubleshooting

Migration Already Applied

Use dotnet ef migrations remove if not applied
Create new migration to revert changes if applied

Conflicting Migrations

Pull latest code and migrations
Remove conflicting migration
Recreate migration

Migration Errors

Check connection string in appsettings.json
Ensure startup project is correct
Verify DbContext registration in Program.cs
Check for model validation errors

CI/CD Integration

Automated Migrations

// Program.cs - Apply migrations on startup (development only)
if (app.Environment.IsDevelopment())
{
    using var scope = app.Services.CreateScope();
    var dbContext = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();
    await dbContext.Database.MigrateAsync();
}

Production Approach

Generate SQL scripts in CI pipeline
Review and apply manually or via deployment automation
Use migration bundles for deployment

Generate clear migration instructions and SQL scripts for safe database schema evolution in .NET 10 applications.

Install ef-migration and it becomes one more candidate the router can pick - when it fits.

A listing is a routing target with a manifest: what it does, which domains it covers, what it costs and who publishes it. Once installed it sits beside your own models and tools, is scored like any other candidate for each request, and shows up in the trace when it wins. Ratings come from workspaces that installed it, one per account.

Create and manage Entity Framework Core migrations following .NET 10 best practices. ## Migration Request {{arguments}} ## Entity Framework Core Migration Workflow ### 1. **Creating a Migration** ```bash # Create a new migration dotnet ef migrations add AddUserTable # With specific DbContext if multiple exist dotnet ef migrations add AddUserTable --context ApplicationDbContext # With specific project and startup project dotnet ef migrations add AddUserTable --project src/YourApp.Data --startup-project src/YourApp.Api ``` ### 2. **Reviewing the Migration** Generated migration files in `Migrations/` folder: - `[Timestamp]_AddUserTable.cs` - The migration class - `[Timestamp]_AddUserTable.Designer.cs` - Snapshot metadata - `ApplicationDbContextModelSnapshot.cs` - Current model snapshot **Example Migration** ```csharp using Microsoft.EntityFrameworkCore.Migrations; public partial class AddUserTable : Migration { protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.CreateTable( name: "Users", columns: table => new { Id = table.Column<int>(nullable: false) .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn), Name = table.Column<string>(maxLength: 100, nullable: false), Email = table.Column<string>(maxLength: 255, nullable: false), CreatedAt = table.Column<DateTime>(type: "timestamp with time zone", nullable: false) }, constraints: table => { table.PrimaryKey("PK_Users", x => x.Id); }); migrationBuilder.CreateIndex( name: "IX_Users_Email", table: "Users", column: "Email", unique: true); } protected override void Down(MigrationBuilder migrationBuilder) { migrationBuilder.DropTable(name: "Users"); } } ``` ### 3. **Applying Migrations** ```bash # Apply all pending migrations to database dotnet ef database update # Apply to specific migration dotnet ef database update AddUserTable # Rollback to previous migration dotnet ef database update PreviousMigrationName # Rollback all migrations dotnet ef database update 0 # Apply to specific environment dotnet ef database update --environment Production ``` ### 4. **Managing Migrations** ```bash # List all migrations dotnet ef migrations list # Remove last migration (if not applied) dotnet ef migrations remove # Generate SQL script from migrations dotnet ef migrations script # Generate SQL for specific migration range dotnet ef migrations script AddUserTable AddOrderTable # Generate idempotent script (safe to run multiple times) dotnet ef migrations script --idempotent # Output SQL to file dotnet ef migrations script --output migrations.sql ``` ### 5. **Database Operations** ```bash # Drop the database (careful!) dotnet ef database drop # Drop and recreate database dotnet ef database drop --force dotnet ef database update # Get connection string information dotnet ef dbcontext info # Scaffold DbContext from existing PostgreSQL database (reverse engineer) dotnet ef dbcontext scaffold "Host=localhost;Database=MyDb;Username=postgres;Password=..." Npgsql.EntityFrameworkCore.PostgreSQL --output-dir Models ``` ## Common Migration Scenarios ### Adding a Column ```csharp // Model change public class User { public int Id { get; set; } public string Name { get; set; } = string.Empty; public string Email { get; set; } = string.Empty; public string PhoneNumber { get; set; } = string.Empty; // New column } // Generated migration migrationBuilder.AddColumn<string>( name: "PhoneNumber", table: "Users", maxLength: 20, nullable: false, defaultValue: ""); ``` ### Renaming a Column ```csharp // Migration (manual edit required) migrationBuilder.RenameColumn( name: "Email", table: "Users", newName: "EmailAddress"); ``` ### Adding an Index ```csharp migrationBuilder.CreateIndex( name: "IX_Users_Email", table: "Users", column: "Email", unique: true); ``` ### Adding a Foreign Key ```csharp migrationBuilder.CreateIndex( name: "IX_Orders_UserId", table: "Orders", column: "UserId"); migrationBuilder.AddForeignKey( name: "FK_Orders_Users_UserId", table: "Orders", column: "UserId", principalTable: "Users", principalColumn: "Id", onDelete: ReferentialAction.Cascade); ``` ### Seeding Data ```csharp protected override void Up(MigrationBuilder migrationBuilder) { migrationBuilder.InsertData( table: "Users", columns: new[] { "Id", "Name", "Email", "CreatedAt" }, values: new object[] { 1, "Admin", "admin@example.com", DateTime.UtcNow }); } ``` ## Best Practices **Migration Naming** - Use descriptive names: `AddUserEmailIndex`, `AddOrderTable` - Follow pattern: `[Action][Entity][Detail]` - Avoid generic names like `Update1`, `Changes` **Before Creating Migration** - Review model changes carefully - Ensure DbContext is configured correctly - Test locally before applying to production **Reviewing Migrations** - Always review generated migration code - Customize Up/Down methods if needed - Add data migration logic for complex changes - Consider backward compatibility **Production Migrations** - Generate SQL script: `dotnet ef migrations script --idempotent` - Review SQL before applying - Have rollback plan ready - Backup database before applying - Apply during maintenance window for major changes **Data Migrations** ```csharp protected override void Up(MigrationBuilder migrationBuilder) { // Schema change migrationBuilder.AddColumn<string>( name: "FullName", table: "Users", nullable: true); // Data migration migrationBuilder.Sql(@" UPDATE Users SET FullName = CONCAT(FirstName, ' ', LastName) WHERE FullName IS NULL "); // Make required after data migration migrationBuilder.AlterColumn<string>( name: "FullName", table: "Users", nullable: false); } ``` **Multiple DbContexts** ```bash # Specify context dotnet ef migrations add MigrationName --context IdentityDbContext dotnet ef database update --context IdentityDbContext ``` **Separate Migrations Assembly** ```csharp services.AddDbContext<ApplicationDbContext>(options => options.UseNpgsql( connectionString, b => b.MigrationsAssembly("YourApp.Data"))); ``` **appsettings.json Connection String** ```json { "ConnectionStrings": { "DefaultConnection": "Host=localhost;Database=myapp;Username=postgres;Password=yourpassword" } } ``` ## Troubleshooting **Migration Already Applied** - Use `dotnet ef migrations remove` if not applied - Create new migration to revert changes if applied **Conflicting Migrations** - Pull latest code and migrations - Remove conflicting migration - Recreate migration **Migration Errors** - Check connection string in appsettings.json - Ensure startup project is correct - Verify DbContext registration in Program.cs - Check for model validation errors ## CI/CD Integration **Automated Migrations** ```csharp // Program.cs - Apply migrations on startup (development only) if (app.Environment.IsDevelopment()) { using var scope = app.Services.CreateScope(); var dbContext = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>(); await dbContext.Database.MigrateAsync(); } ``` **Production Approach** - Generate SQL scripts in CI pipeline - Review and apply manually or via deployment automation - Use migration bundles for deployment Generate clear migration instructions and SQL scripts for safe database schema evolution in .NET 10 applications.

{ "prompt": "Create and manage Entity Framework Core migrations following .NET 10 best practices.\n\n## Migration Request\n\n{{arguments}}\n\n## Entity Framework Core Migration Workflow\n\n### 1. **Creating a Migration**\n\n```bash\n# Create a new migration\ndotnet ef migrations add AddUserTable\n\n# With specific DbContext if multiple exist\ndotnet ef migrations add AddUserTable --context ApplicationDbContext\n\n# With specific project and startup project\ndotnet ef migrations add AddUserTable --project src/YourApp.Data --startup-project src/YourApp.Api\n```\n\n### 2. **Reviewing the Migration**\n\nGenerated migration files in `Migrations/` folder:\n- `[Timestamp]_AddUserTable.cs` - The migration class\n- `[Timestamp]_AddUserTable.Designer.cs` - Snapshot metadata\n- `ApplicationDbContextModelSnapshot.cs` - Current model snapshot\n\n**Example Migration**\n```csharp\nusing Microsoft.EntityFrameworkCore.Migrations;\n\npublic partial class AddUserTable : Migration\n{\n protected override void Up(MigrationBuilder migrationBuilder)\n {\n migrationBuilder.CreateTable(\n name: \"Users\",\n columns: table => new\n {\n Id = table.Column<int>(nullable: false)\n .Annotation(\"Npgsql:ValueGenerationStrategy\", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),\n Name = table.Column<string>(maxLength: 100, nullable: false),\n Email = table.Column<string>(maxLength: 255, nullable: false),\n CreatedAt = table.Column<DateTime>(type: \"timestamp with time zone\", nullable: false)\n },\n constraints: table =>\n {\n table.PrimaryKey(\"PK_Users\", x => x.Id);\n });\n\n migrationBuilder.CreateIndex(\n name: \"IX_Users_Email\",\n table: \"Users\",\n column: \"Email\",\n unique: true);\n }\n\n protected override void Down(MigrationBuilder migrationBuilder)\n {\n migrationBuilder.DropTable(name: \"Users\");\n }\n}\n```\n\n### 3. **Applying Migrations**\n\n```bash\n# Apply all pending migrations to database\ndotnet ef database update\n\n# Apply to specific migration\ndotnet ef database update AddUserTable\n\n# Rollback to previous migration\ndotnet ef database update PreviousMigrationName\n\n# Rollback all migrations\ndotnet ef database update 0\n\n# Apply to specific environment\ndotnet ef database update --environment Production\n```\n\n### 4. **Managing Migrations**\n\n```bash\n# List all migrations\ndotnet ef migrations list\n\n# Remove last migration (if not applied)\ndotnet ef migrations remove\n\n# Generate SQL script from migrations\ndotnet ef migrations script\n\n# Generate SQL for specific migration range\ndotnet ef migrations script AddUserTable AddOrderTable\n\n# Generate idempotent script (safe to run multiple times)\ndotnet ef migrations script --idempotent\n\n# Output SQL to file\ndotnet ef migrations script --output migrations.sql\n```\n\n### 5. **Database Operations**\n\n```bash\n# Drop the database (careful!)\ndotnet ef database drop\n\n# Drop and recreate database\ndotnet ef database drop --force\ndotnet ef database update\n\n# Get connection string information\ndotnet ef dbcontext info\n\n# Scaffold DbContext from existing PostgreSQL database (reverse engineer)\ndotnet ef dbcontext scaffold \"Host=localhost;Database=MyDb;Username=postgres;Password=...\" Npgsql.EntityFrameworkCore.PostgreSQL --output-dir Models\n```\n\n## Common Migration Scenarios\n\n### Adding a Column\n```csharp\n// Model change\npublic class User\n{\n public int Id { get; set; }\n public string Name { get; set; } = string.Empty;\n public string Email { get; set; } = string.Empty;\n public string PhoneNumber { get; set; } = string.Empty; // New column\n}\n\n// Generated migration\nmigrationBuilder.AddColumn<string>(\n name: \"PhoneNumber\",\n table: \"Users\",\n maxLength: 20,\n nullable: false,\n defaultValue: \"\");\n```\n\n### Renaming a Column\n```csharp\n// Migration (manual edit required)\nmigrationBuilder.RenameColumn(\n name: \"Email\",\n table: \"Users\",\n newName: \"EmailAddress\");\n```\n\n### Adding an Index\n```csharp\nmigrationBuilder.CreateIndex(\n name: \"IX_Users_Email\",\n table: \"Users\",\n column: \"Email\",\n unique: true);\n```\n\n### Adding a Foreign Key\n```csharp\nmigrationBuilder.CreateIndex(\n name: \"IX_Orders_UserId\",\n table: \"Orders\",\n column: \"UserId\");\n\nmigrationBuilder.AddForeignKey(\n name: \"FK_Orders_Users_UserId\",\n table: \"Orders\",\n column: \"UserId\",\n principalTable: \"Users\",\n principalColumn: \"Id\",\n onDelete: ReferentialAction.Cascade);\n```\n\n### Seeding Data\n```csharp\nprotected override void Up(MigrationBuilder migrationBuilder)\n{\n migrationBuilder.InsertData(\n table: \"Users\",\n columns: new[] { \"Id\", \"Name\", \"Email\", \"CreatedAt\" },\n values: new object[] { 1, \"Admin\", \"admin@example.com\", DateTime.UtcNow });\n}\n```\n\n## Best Practices\n\n**Migration Naming**\n- Use descriptive names: `AddUserEmailIndex`, `AddOrderTable`\n- Follow pattern: `[Action][Entity][Detail]`\n- Avoid generic names like `Update1`, `Changes`\n\n**Before Creating Migration**\n- Review model changes carefully\n- Ensure DbContext is configured correctly\n- Test locally before applying to production\n\n**Reviewing Migrations**\n- Always review generated migration code\n- Customize Up/Down methods if needed\n- Add data migration logic for complex changes\n- Consider backward compatibility\n\n**Production Migrations**\n- Generate SQL script: `dotnet ef migrations script --idempotent`\n- Review SQL before applying\n- Have rollback plan ready\n- Backup database before applying\n- Apply during maintenance window for major changes\n\n**Data Migrations**\n```csharp\nprotected override void Up(MigrationBuilder migrationBuilder)\n{\n // Schema change\n migrationBuilder.AddColumn<string>(\n name: \"FullName\",\n table: \"Users\",\n nullable: true);\n\n // Data migration\n migrationBuilder.Sql(@\"\n UPDATE Users\n SET FullName = CONCAT(FirstName, ' ', LastName)\n WHERE FullName IS NULL\n \");\n\n // Make required after data migration\n migrationBuilder.AlterColumn<string>(\n name: \"FullName\",\n table: \"Users\",\n nullable: false);\n}\n```\n\n**Multiple DbContexts**\n```bash\n# Specify context\ndotnet ef migrations add MigrationName --context IdentityDbContext\ndotnet ef database update --context IdentityDbContext\n```\n\n**Separate Migrations Assembly**\n```csharp\nservices.AddDbContext<ApplicationDbContext>(options =>\n options.UseNpgsql(\n connectionString,\n b => b.MigrationsAssembly(\"YourApp.Data\")));\n```\n\n**appsettings.json Connection String**\n```json\n{\n \"ConnectionStrings\": {\n \"DefaultConnection\": \"Host=localhost;Database=myapp;Username=postgres;Password=yourpassword\"\n }\n}\n```\n\n## Troubleshooting\n\n**Migration Already Applied**\n- Use `dotnet ef migrations remove` if not applied\n- Create new migration to revert changes if applied\n\n**Conflicting Migrations**\n- Pull latest code and migrations\n- Remove conflicting migration\n- Recreate migration\n\n**Migration Errors**\n- Check connection string in appsettings.json\n- Ensure startup project is correct\n- Verify DbContext registration in Program.cs\n- Check for model validation errors\n\n## CI/CD Integration\n\n**Automated Migrations**\n```csharp\n// Program.cs - Apply migrations on startup (development only)\nif (app.Environment.IsDevelopment())\n{\n using var scope = app.Services.CreateScope();\n var dbContext = scope.ServiceProvider.GetRequiredService<ApplicationDbContext>();\n await dbContext.Database.MigrateAsync();\n}\n```\n\n**Production Approach**\n- Generate SQL scripts in CI pipeline\n- Review and apply manually or via deployment automation\n- Use migration bundles for deployment\n\nGenerate clear migration instructions and SQL scripts for safe database schema evolution in .NET 10 applications.", "variables": [ "arguments" ], "notes": "Create and manage Entity Framework Core migrations for database schema changes", "metadata": { "source": { "provider": "github-claude-commands", "repository": "https://github.com/yoozek/yoozek-claude-code", "path": ".claude/commands/dotnet/ef-migration.md", "ref": "7fc5d3edd03da741495dddf84186dbbb8ac4db99", "url": "https://github.com/yoozek/yoozek-claude-code/blob/7fc5d3edd03da741495dddf84186dbbb8ac4db99/.claude/commands/dotnet/ef-migration.md", "key": "yoozek/yoozek-claude-code/.claude/commands/dotnet/ef-migration.md" } }, "model_hints": [ "claude-sonnet-4-5" ] }

ef-migration

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