[ASP.Net Core MVC] Entity Framework Core 1 - 다대다관계

ORM 인 Entiry Framework Core 를 바탕으로 다대다관계를 구성해보도록 하자.

다대다 관계는 보통의 경우 1:다:1 형태로 임의의 중간 테이블을 별도로 만들고 이를 연결하는 형태로 구성한다.

이때 1:다는 각각 ForeignKey 형태로 연결시킨다.

 

관련 예제는 MS 의 ASP.Net Core 자습서를 참고 하였다.

https://docs.microsoft.com/ko-kr/aspnet/core/data/ef-mvc/intro?view=aspnetcore-3.1 

자습서: ASP.NET MVC 웹앱에서 EF Core 시작

 

깃허브 전체 소스는 아래의 주소와 같다.

https://github.com/dotnet/AspNetCore.Docs/tree/main/aspnetcore/data/ef-mvc/intro/samples/cu-final

GitHub - dotnet/AspNetCore.Docs: Documentation for ASP.NET Core

 

상기 이미지와 같애 Course 와 Student 간의 다대다 관계를 Enrollment 엔터티로 연결하여 1:다:1 처리를 하고 있다.

 

[ /Models/Course.cs ]

 

using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
 
namespace ContosoUniversity.Models
{
    public class Course
    {
        [DatabaseGenerated(DatabaseGeneratedOption.None)]
        public int CourseID { get; set; }
        public string Title { get; set; }
        public int Credits { get; set; }
 
        public ICollection<Enrollment> Enrollments { get; set; }
    }
}

 

[ /Models/Student.cs ]

 

using System;
using System.Collections.Generic;
 
namespace ContosoUniversity.Models
{
    public class Student
    {
        public int ID { get; set; }
        public string LastName { get; set; }
        public string FirstMidName { get; set; }
        public DateTime EnrollmentDate { get; set; }
 
        public ICollection<Enrollment> Enrollments { get; set; }
    }
}

 

 

[ /Models/Enrollment.cs ]

 

namespace ContosoUniversity.Models
{
    public enum Grade
    {
        A=1, B, C, D, F
    }
 
    public class Enrollment
    {
        public int EnrollmentID { get; set; }
        public int CourseID { get; set; }
        public int StudentID { get; set; }
        public Grade? Grade { get; set; }
 
        public Course Course { get; set; }
        public Student Student { get; set; }
    }
}

 

[ /Data/SchoolContext.cs ]

 

using ContosoUniversity.Models;
using Microsoft.EntityFrameworkCore;
 
namespace ContosoUniversity.Data
{
    public class SchoolContext : DbContext
    {
        public SchoolContext(DbContextOptions<SchoolContext> options) : base(options)
        {
 
        }
 
        public DbSet<Course> Courses { get; set; }
        public DbSet<Student> Students { get; set; }
        public DbSet<Enrollment> Enrollments { get; set; }
 
        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Course>().ToTable("Course");
            modelBuilder.Entity<Student>().ToTable("Student");
            modelBuilder.Entity<Enrollment>().ToTable("Enrollment");
        }
    }
}

SchoolContext 는 DbContext 를 상속하고, 아래의 Startup.cs 내에 서비스항목에 추가 시켜준다.

아래의 Startup.cs 에서 31라인지점이다.

 

[ Startup.cs ]

 

using ContosoUniversity.Data;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
 
namespace ContosoUniversity
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }
 
        public IConfiguration Configuration { get; }
        public void ConfigureServices(IServiceCollection services)
        {
            // 세션추가
            services.AddSession();
            services.AddControllersWithViews();
 
            // DB Context추가
            services.AddDbContext<SchoolContext>(options => options.UseSqlServer(Configuration.GetConnectionString("AppDb")));
        }
 
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
 
            app.UseRouting();
 
            app.UseAuthorization();
 
            // 세션사용
            app.UseSession();
 
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}
 

 

 

[ appsettings.json ]

 

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "AppDb": "Server=DESKTOP-ASIDMUS;Database=ContosoUniversity;Trusted_Connection=True;MultipleActiveResultSets=true"
  }
}
 

 

 

3개의 테이블은 아래의 소스로 스크립트파일로 정리해 놓았다.

ContosoUniversity.sql

0.00MB

Course

Enrollment

Student

 

참고 : https://www.entityframeworktutorial.net/code-first/configure-one-to-many-relationship-in-code-first.aspx

참고 : https://www.entityframeworktutorial.net/code-first/configure-many-to-many-relationship-in-code-first.aspx

참고1 : https://docs.microsoft.com/ko-kr/aspnet/core/data/ef-mvc/read-related-data?view=aspnetcore-3.1 

참고2 : https://dleunji.tistory.com/45?category=999005 

참고3 : https://www.learnentityframeworkcore.com/relationships

참고4 : https://forum.dotnetdev.kr/t/ef-core-6-2/3716

참고5 : https://www.learnentityframeworkcore.com/configuration/many-to-many-relationship-configuration