NorthwindContextExtensions.cs

using Microsoft.Data.SqlClient; // To use SqlConnectionStringBuilder.
using Microsoft.EntityFrameworkCore; // To use the UseSqlServer method.
using Microsoft.Extensions.DependencyInjection; // To use IServiceCollection.

namespace Northwind.EntityModels;

public static class NorthwindContextExtensions
{
  /// <summary>
  /// Adds NorthwindContext to the specified IServiceCollection. Uses the SqlServer database provider.
  /// </summary>
  /// <param name="services">The service collection.</param>
  /// <param name="connectionString">Set to override the default.</param>
  /// <returns>An IServiceCollection that can be used to add more services.</returns>
  public static IServiceCollection AddNorthwindContext(
    this IServiceCollection services, // The type to extend.
    string? connectionString = null)
  {
    if (connectionString is null)
    {
      SqlConnectionStringBuilder builder = new();

      builder.DataSource = "tcp:127.0.0.1,1433"; // SQL Edge in Docker.
      builder.InitialCatalog = "Northwind";
      builder.TrustServerCertificate = true;
      builder.MultipleActiveResultSets = true;

      // Because we want to fail faster. Default is 15 seconds.
      builder.ConnectTimeout = 3;

      // SQL Server authentication.
      builder.UserID = Environment.GetEnvironmentVariable("MY_SQL_USR");
      builder.Password = Environment.GetEnvironmentVariable("MY_SQL_PWD");

      connectionString = builder.ConnectionString;
    }

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

      options.LogTo(NorthwindContextLogger.WriteLine,
        new[] { Microsoft.EntityFrameworkCore
          .Diagnostics.RelationalEventId.CommandExecuting });
    },
    // Register with a transient lifetime to avoid concurrency 
    // issues with Blazor Server projects.
    contextLifetime: ServiceLifetime.Transient,
    optionsLifetime: ServiceLifetime.Transient);

    return services;
  }
}