Migrations

Create and manage database migrations for TickerQ entities.

Creating Migrations

Using Built-in TickerQDbContext

# Add migration
dotnet ef migrations add TickerQInitialCreate --context TickerQDbContext

# Apply migration
dotnet ef database update --context TickerQDbContext

Using Application DbContext

# Add migration (includes TickerQ entities)
dotnet ef migrations add AddTickerQSupport --context MyApplicationDbContext

# Apply migration
dotnet ef database update --context MyApplicationDbContext

Using Custom Entities

# Add migration
dotnet ef migrations add CustomEntitiesInitialCreate --context MyTickerQDbContext

# Apply migration
dotnet ef database update --context MyTickerQDbContext

Migration Setup

Prerequisites

Ensure Entity Framework Core tools are installed:

dotnet tool install --global dotnet-ef

Connection String

Configure connection string in appsettings.json:

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=localhost;Database=TickerQDb;Trusted_Connection=true;"
  }
}

DbContext Configuration

services.AddDbContext<TickerQDbContext>(options =>
    options.UseSqlServer(connectionString));

// Or for application DbContext
services.AddDbContext<MyApplicationDbContext>(options =>
    options.UseSqlServer(connectionString));

Design-time DbContext Factory

For migrations to work, create a design-time factory:

public class TickerQDbContextFactory : IDesignTimeDbContextFactory<TickerQDbContext>
{
    public TickerQDbContext CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<TickerQDbContext>();
        optionsBuilder.UseSqlServer("Server=localhost;Database=TickerQDb;Trusted_Connection=true;");
        
        return new TickerQDbContext(optionsBuilder.Options);
    }
}

Migration Files

TickerQ migrations typically include:

• TimeTicker table with scheduling and execution tracking
• CronTicker table with cron expression support
• CronOccurrence table for cron execution history
• Indexes for performance optimization
• Foreign key relationships between entities

Schema Customization

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    // Custom schema
    modelBuilder.HasDefaultSchema("job_scheduler");
    
    // Configure TickerQ entities
    modelBuilder.ConfigureTickerQ();
}

// Migration creates tables in "job_scheduler" schema

Reviewing Migrations

Always review generated migration files before applying:

# Generate migration (dry run)
dotnet ef migrations add ReviewMigration --context TickerQDbContext

# Review the generated files in Migrations/ folder
# Then apply when ready
dotnet ef database update --context TickerQDbContext

Migration Best Practices

1. Test in Development: Always test migrations in development first
2. Backup Production: Create database backups before applying migrations to production
3. Review Changes: Review generated migration files before applying
4. Incremental Updates: Create separate migrations for each schema change
5. Version Control: Commit migration files to version control

Rolling Back Migrations

Remove the last migration:

dotnet ef migrations remove --context TickerQDbContext

Roll back to a specific migration:

dotnet ef database update PreviousMigrationName --context TickerQDbContext

Migration Examples

Initial Migration

dotnet ef migrations add InitialTickerQSchema --context TickerQDbContext

Generated migration includes:

• TimeTicker table creation
• CronTicker table creation
• CronOccurrence table creation
• Indexes and constraints
• Foreign key relationships

Adding Custom Properties

public class MyTimeTicker : TimeTicker
{
    public string TenantId { get; set; }
}

# Generate migration
dotnet ef migrations add AddTenantIdToTimeTicker --context MyTickerQDbContext

Migration adds the new column to existing table.

Automated Migration

Apply migrations during application startup:

public static void Main(string[] args)
{
    var host = CreateHostBuilder(args).Build();
    
    using (var scope = host.Services.CreateScope())
    {
        var context = scope.ServiceProvider.GetRequiredService<TickerQDbContext>();
        context.Database.Migrate(); // Apply pending migrations
    }
    
    host.Run();
}

Manual Migration

For production, prefer manual migration control:

# Docker deployment example
version: '3.8'
services:
  migration:
    image: myapp:latest
    command: dotnet ef database update --context TickerQDbContext
    environment:
      - ConnectionStrings__DefaultConnection=...
    depends_on:
      - database
      
  app:
    image: myapp:latest
    depends_on:
      - migration

Or in CI/CD pipeline:

- name: Run Migrations
  run: |
    dotnet ef database update --context TickerQDbContext
    --connection "${{ secrets.CONNECTION_STRING }}"

Troubleshooting

Migration Conflicts

If multiple developers create migrations simultaneously:

• Merge conflicts in migration files
• Or manually resolve conflicts in migration files

Design-time Issues

If migration tools can't create DbContext:

• Ensure IDesignTimeDbContextFactory is implemented
• Check connection string accessibility
• Verify EF Core tools are installed

Schema Issues

• Check migration files for correct schema specification
• Ensure custom schema is configured in OnModelCreating
• Verify database permissions for schema creation

Next Steps

• Database Operations - Query and manage data
• Performance - Optimization strategies
• Best Practices - Production recommendations