cs11dotnet7/vscode/Chapter10/CoursesAndStudents/Academy.cs

using Microsoft.EntityFrameworkCore; // DbContext, DbSet<T>

namespace Packt.Shared;

public class Academy : DbContext
{
  public DbSet<Student>? Students { get; set; }
  public DbSet<Course>? Courses { get; set; }

  protected override void OnConfiguring(
    DbContextOptionsBuilder optionsBuilder)
  {
    string path = Path.Combine(
      Environment.CurrentDirectory, "Academy.db");

    string connection = $"Filename={path}";
    // string connection = @"Data Source=.;Initial Catalog=Academy;Integrated Security=true;MultipleActiveResultSets=true;";

    WriteLine($"Connection: {connection}");

    optionsBuilder.UseSqlite(connection);
    // optionsBuilder.UseSqlServer(connection);
  }

  protected override void OnModelCreating(ModelBuilder modelBuilder)
  {
    // Fluent API validation rules
    modelBuilder.Entity<Student>()
      .Property(s => s.LastName).HasMaxLength(30).IsRequired();

    // populate database with sample data
    Student alice = new()
    {
      StudentId = 1,
      FirstName = "Alice",
      LastName = "Jones"
    };

    Student bob = new()
    {
      StudentId = 2,
      FirstName = "Bob",
      LastName = "Smith"
    };

    Student cecilia = new()
    {
      StudentId = 3,
      FirstName = "Cecilia",
      LastName = "Ramirez"
    };

    Course csharp = new()
    {
      CourseId = 1,
      Title = "C# 10 and .NET 6"
    };

    Course webdev = new()
    {
      CourseId = 2,
      Title = "Web Development"
    };
    
    Course python = new()
    {
      CourseId = 3,
      Title = "Python for Beginners"
    };

    modelBuilder.Entity<Student>()
      .HasData(alice, bob, cecilia);

    modelBuilder.Entity<Course>()
      .HasData(csharp, webdev, python);
    
    modelBuilder.Entity<Course>()
      .HasMany(c => c.Students)
      .WithMany(s => s.Courses)
      .UsingEntity(e => e.HasData(
        // all students signed up for C# course
        new { CoursesCourseId = 1, StudentsStudentId = 1 },
        new { CoursesCourseId = 1, StudentsStudentId = 2 },
        new { CoursesCourseId = 1, StudentsStudentId = 3 },
        // only Bob signed up for Web Dev
        new { CoursesCourseId = 2, StudentsStudentId = 2 },
        // only Cecilia signed up for Python
        new { CoursesCourseId = 3, StudentsStudentId = 3 }
      ));
  }
}