Entity Framework Core Migration Quick Reference

Common Commands

Prerequisites

# Install EF Core tools (one-time setup)
dotnet tool install --global dotnet-ef

# Update EF Core tools
dotnet tool update --global dotnet-ef

# Verify installation
dotnet ef --version

Creating Migrations

1. Add New Migration

# Navigate to project directory
cd SecureBootDashboard.Api

# Create migration
dotnet ef migrations add MigrationName

# Create migration with startup project (if different)
dotnet ef migrations add MigrationName --startup-project ../SecureBootDashboard.Web

Naming conventions:

AddColumnNameToTable - e.g., AddClientVersionToDevice
CreateTableName - e.g., CreateAuditLog
UpdateTableNameStructure - e.g., UpdateDeviceStructure

2. Remove Last Migration (if not applied)

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

# Force remove (use with caution)
dotnet ef migrations remove --force

?? Warning: Only remove migrations that haven't been applied to the database!

Applying Migrations

1. Apply All Pending Migrations

# Apply to database specified in appsettings.json
dotnet ef database update

# Apply with custom connection string
dotnet ef database update --connection "Server=...;Database=...;Trusted_Connection=True"

2. Apply to Specific Migration

# Apply up to specific migration
dotnet ef database update MigrationName

# Rollback to specific migration
dotnet ef database update PreviousMigrationName

3. Rollback All Migrations

# Remove all migrations from database (keeps data)
dotnet ef database update 0

?? Warning: This will drop all tables!

Inspecting Migrations

1. List All Migrations

dotnet ef migrations list

Output:

20251105093532_InitialCreate (Applied)
20251105101836_AddCertificateCollection (Applied)
20251109202217_AddClientVersionToDevice (Pending)

2. View Migration SQL

# Generate SQL for next migration
dotnet ef migrations script

# Generate SQL for specific migration
dotnet ef migrations script PreviousMigration TargetMigration

# Generate SQL for all pending migrations
dotnet ef migrations script --idempotent

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

3. Check Database Schema

# Generate SQL to create database from scratch
dotnet ef dbcontext script

# Output to file
dotnet ef dbcontext script --output schema.sql

Database Operations

1. Drop Database

# Drop database (all data lost!)
dotnet ef database drop

# Drop without confirmation
dotnet ef database drop --force

2. Rebuild Database

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

Troubleshooting Commands

1. Verify DbContext

# List all DbContexts in project
dotnet ef dbcontext list

# View DbContext info
dotnet ef dbcontext info

2. Generate Migration Bundle

# Create self-contained migration executable
dotnet ef migrations bundle

# Specify output
dotnet ef migrations bundle --output migrations.exe

# Run bundle
.\migrations.exe --connection "Server=...;Database=...;Trusted_Connection=True"

3. Debug Build Issues

# Clean build
dotnet clean
dotnet build

# Verbose output
dotnet ef database update --verbose

Configuration Files

appsettings.json

{
  "ConnectionStrings": {
    "SqlServer": "Server=SRVSQL;Database=SecureBootDashboard;Trusted_Connection=True;TrustServerCertificate=True"
  }
}

appsettings.Development.json

{
  "ConnectionStrings": {
    "SqlServer": "Server=localhost;Database=SecureBootDashboard_Dev;Trusted_Connection=True;TrustServerCertificate=True"
  }
}

Migration File Structure

Example Migration

public partial class AddClientVersionToDevice : Migration
{
    protected override void Up(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.AddColumn<string>(
            name: "ClientVersion",
            table: "Devices",
            type: "nvarchar(50)",
            maxLength: 50,
            nullable: true);
    }

    protected override void Down(MigrationBuilder migrationBuilder)
    {
        migrationBuilder.DropColumn(
            name: "ClientVersion",
            table: "Devices");
    }
}

Common Scenarios

Scenario 1: Add New Column

# 1. Update entity model (DeviceEntity.cs)
# 2. Create migration
dotnet ef migrations add AddNewColumnToDevice

# 3. Review generated migration
code Data/Migrations/*_AddNewColumnToDevice.cs

# 4. Apply migration
dotnet ef database update

Scenario 2: Rename Column

# 1. Update entity model
# 2. Create migration
dotnet ef migrations add RenameOldColumnToNewColumn

# 3. Edit migration to use RenameColumn (not Add/Drop)
# 4. Apply migration
dotnet ef database update

Manual edit example:

protected override void Up(MigrationBuilder migrationBuilder)
{
    migrationBuilder.RenameColumn(
        name: "OldName",
        table: "Devices",
        newName: "NewName");
}

Scenario 3: Change Column Type

# 1. Update entity model
# 2. Create migration
dotnet ef migrations add ChangeColumnTypeForDevice

# 3. Apply migration (may require data migration)
dotnet ef database update

Scenario 4: Fix Broken Migration

# Option 1: Remove last migration (if not applied)
dotnet ef migrations remove

# Option 2: Rollback to previous migration
dotnet ef database update PreviousMigrationName

# Option 3: Create new migration to fix
dotnet ef migrations add FixBrokenMigration

Best Practices

? DO

Always review generated migrations before applying
Test migrations on development database first
Use meaningful migration names
Commit migrations to source control
Generate SQL scripts for production deployments
Back up database before major migrations
Use idempotent scripts for production

? DON'T

Don't remove applied migrations from source control
Don't modify applied migrations (create new one instead)
Don't skip testing migrations
Don't apply migrations directly to production (use scripts)
Don't forget to update model snapshot
Don't use database drop in production

Production Deployment Workflow

Step 1: Generate SQL Script

# Development environment
dotnet ef migrations script --idempotent --output migration.sql

Step 2: Review Script

# Review SQL before applying
code migration.sql

Step 3: Backup Production Database

-- SQL Server Management Studio
BACKUP DATABASE SecureBootDashboard
TO DISK = 'C:\Backups\SecureBootDashboard_PreMigration.bak'
WITH INIT, COMPRESSION;

Step 4: Apply Script

-- Execute migration.sql in SSMS
-- Or use sqlcmd:
sqlcmd -S SRVSQL -d SecureBootDashboard -i migration.sql

Step 5: Verify

-- Check applied migrations
SELECT * FROM __EFMigrationsHistory
ORDER BY MigrationId DESC;

Environment-Specific Migrations

Development

# Use Development connection string
$env:ASPNETCORE_ENVIRONMENT = "Development"
dotnet ef database update

Production

# Use Production connection string
$env:ASPNETCORE_ENVIRONMENT = "Production"
dotnet ef migrations script --idempotent --output production_migration.sql

Automated Scripts

Check and Apply Migrations

# Use provided script
.\scripts\Apply-DatabaseMigrations.ps1 -Force

Custom Automation

# Check if migrations needed
$pendingMigrations = dotnet ef migrations list 2>&1 | Select-String "Pending"

if ($pendingMigrations) {
    Write-Host "Pending migrations found. Applying..."
    dotnet ef database update
} else {
    Write-Host "Database is up to date."
}

Quick Troubleshooting

Error	Solution
`dotnet ef: command not found`	`dotnet tool install --global dotnet-ef`
`Build failed`	`dotnet clean && dotnet build`
`Unable to create migration`	Check entity model changes
`Login failed`	Verify connection string
`Network-related error`	Check SQL Server service is running
`Duplicate migration`	Remove duplicate with `migrations remove`
`Column already exists`	Check if migration already applied
`Foreign key constraint`	Review migration order

Useful Queries

Check Pending Migrations

dotnet ef migrations list | Select-String "Pending"

Check Applied Migrations

-- Direct database query
SELECT * FROM __EFMigrationsHistory
ORDER BY MigrationId DESC;

Compare Model vs Database

# Generate current model script
dotnet ef dbcontext script --output current_model.sql

# Compare with database
# Use SQL Server Schema Compare tool

Related Resources

Official Documentation: https://learn.microsoft.com/en-us/ef/core/managing-schemas/migrations/
Migration Tutorial: https://learn.microsoft.com/en-us/ef/core/get-started/overview/first-app
Database Providers: https://learn.microsoft.com/en-us/ef/core/providers/

Quick Command Reference Card

# Create migration
dotnet ef migrations add MigrationName

# Apply migrations
dotnet ef database update

# List migrations
dotnet ef migrations list

# Generate SQL
dotnet ef migrations script --idempotent

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

# Drop database
dotnet ef database drop --force

Last Updated: 2025-01-10

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