EF CORE EntityFrameworkCore中关系模式一对一、一对多、多对多的使用
EF CORE EntityFrameworkCore中关系模式一对一、一对多、多对多的使用。
使用VS2019 新建.Net Core Console控制台项目，使用NuGet程序包管理器添加引用如下：
具体代码如下：
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata.Builders;
using System;
using Microsoft.Extensions.Logging;
using System.Collections.Generic;
namespace TestNetCore
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello World!");
TestDBConext testDB = new TestDBConext();
testDB.Database.EnsureDeleted();
if (testDB.Database.EnsureCreated())
{
Console.WriteLine("数据库创建成功");
}
#region 测试一对一
//Person person = testDB.Find(10);
//testDB.Remove(person);
//testDB.SaveChanges();
#endregion
#region 测试一对多
//Product product = testDB.Find(10);
//testDB.Remove(product);
//testDB.SaveChanges();
#endregion
#region 测试多对多
//Student student = testDB.Find(2);
//testDB.Remove(student);
//testDB.SaveChanges();
//Teacher teacher = testDB.Find(8);
//testDB.Remove(teacher);
//testDB.SaveChanges();
#endregion
Console.ForegroundColor = ConsoleColor.Blue;
Console.WriteLine("成功");
Console.ReadLine();
}
}
#region EntityFrameworkCore DbContext
public class TestDBConext : DbContext
{
public TestDBConext()
{
}
//public DbSet Persons { get; set; }第一种EF to DB映射方式
//public DbSet IdCards { get; set; }第一种EF to DB映射方式
//public DbSet Products { get; set; }第一种EF to DB映射方式
//public DbSet Categorys { get; set; }第一种EF to DB映射方式
//public DbSet Teachers { get; set; }第一种EF to DB映射方式
//public DbSet Students { get; set; }第一种EF to DB映射方式
public static readonly ILoggerFactory loggerFactory = LoggerFactory.Create(op => op.AddConsole().AddConsole());
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer("Server =localhost;Database=mytest;Persist Security Info=True;User Id=sa;Password=sa123;");
//optionsBuilder.UseMySql("Server =localhost;Database=mytest;User Id=root;Password=123456;");
optionsBuilder.UseLoggerFactory(loggerFactory);
base.OnConfiguring(optionsBuilder);
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
#region 一对一
//HasData()初始化参数
//List list = new List();
//List listIdCard = new List();
//for (int i = 0; i < 10; i++)
//{
// Person person = new Person { Id = i + 1, Name = $"{i}:name", IdCardId = i + 2 };
// list.Add(person);
// IdCard idCard = new IdCard { Id = i + 2, Name = $"{i}:name", PersonId = i + 1 };
// listIdCard.Add(idCard);
//}
#region 第二种EF to DB映射方式
//创建表结构
////modelBuilder.Entity()
////.HasOne(a => a.IdCard).WithOne(a => a.Person).
////HasForeignKey(a => a.PersonId).OnDelete(DeleteBehavior.Cascade)//默认级联删除，即删除person就删除IdCard，这一句和下面一句效果一样
//modelBuilder.Entity().HasOne(a => a.IdCard).WithOne(a => a.Person).HasForeignKey(a => a.PersonId);
//初始化表数据
//modelBuilder.Entity().HasData(list);
//modelBuilder.Entity().HasData(listIdCard);
#endregion
#region 第三种EF to DB映射方式
////创建表结构
//modelBuilder.ApplyConfiguration(new PersonMap());
//modelBuilder.ApplyConfiguration(new IdCardMap());
////初始化表数据
//modelBuilder.Entity().HasData(list);
//modelBuilder.Entity().HasData(listIdCard);
#endregion
#endregion
#region 一对多
////HasData()初始化参数
//List list = new List();
//List listCategory = new List();
////List productCategories = new List();
//for (int i = 0; i < 10; i++)
//{
// Product product = new Product { Id = i + 1, ProductName = $"{i}:Productname" };
// //var arry = Enumerable.Range(1, i).ToArray();
// for (int j = 0; j < i; j++)
// {
// Category category = new Category { Id = j + i * 10, CategoryName = $"{j}:Categoryname", ProductId = product.Id };
// listCategory.Add(category);
// }
// list.Add(product);
//}
#region 第二种EF to DB映射方式
////创建表结构
////modelBuilder.Entity().HasMany(a => a.Categories).WithOne(a => a.Product).OnDelete(DeleteBehavior.Cascade)//默认级联删除，即删除person就删除IdCard，
////这一句和下面一句效果一样
//modelBuilder.Entity().HasMany(a => a.Categories).WithOne(a => a.Product);
////初始化表数据
//modelBuilder.Entity().HasData(list);
//modelBuilder.Entity().HasData(listCategory);
#endregion
#region 第三种EF to DB映射方式
////创建表结构
//modelBuilder.ApplyConfiguration(new ProductMap());
//modelBuilder.ApplyConfiguration(new CategoryMap());
////初始化表数据
//modelBuilder.Entity().HasData(list);
//modelBuilder.Entity().HasData(listCategory);
#endregion
#endregion
#region 多对多
//HasData()初始化参数
List list = new List
{
new Student { Id = 1, StudentName = $"StudentName 1" },
new Student { Id = 2, StudentName = $"StudentName 2" },
new Student { Id = 3, StudentName = $"StudentName 3" },
new Student { Id = 4, StudentName = $"StudentName 4" }
};
List listTeacher = new List
{
new Teacher { Id = 6, TeacherName = $"StudentName 6" },
new Teacher { Id = 7, TeacherName = $"StudentName 7" },
new Teacher { Id = 8, TeacherName = $"StudentName 8" },
new Teacher { Id = 9, TeacherName = $"StudentName 9" }
};
List studentTeacher = new List
{
new StudentTeacher { StudentId = 1, TeacherId = 6 },
new StudentTeacher { StudentId = 2, TeacherId = 6 },
new StudentTeacher { StudentId = 3, TeacherId = 6 },
new StudentTeacher { StudentId = 4, TeacherId = 6 },
new StudentTeacher { StudentId = 2, TeacherId = 8 },
new StudentTeacher { StudentId = 3, TeacherId = 8 },
new StudentTeacher { StudentId = 4, TeacherId = 8 }
};
#region 第二种EF to DB映射方式
//创建表结构
//////modelBuilder.Entity().HasMany(a => a.StudentTeachers).WithOne(a => a.Student).OnDelete(DeleteBehavior.Cascade)
//////modelBuilder.Entity().HasMany(a => a.StudentTeachers).WithOne(a => a.Teacher).OnDelete(DeleteBehavior.Cascade)
//modelBuilder.Entity().HasMany(a => a.StudentTeachers).WithOne(a => a.Student);
//modelBuilder.Entity().HasMany(a => a.StudentTeachers).WithOne(a => a.Teacher);
//modelBuilder.Entity().HasKey(a => new { a.StudentId, a.TeacherId });
////modelBuilder.Entity().HasOne(a => a.Student).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.StudentId);
////modelBuilder.Entity().HasOne(a => a.Teacher).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.TeacherId);
//////初始化表数据
//modelBuilder.Entity().HasData(list);
//modelBuilder.Entity().HasData(listTeacher);
//modelBuilder.Entity().HasData(studentTeacher);
#endregion
#region 第三种EF to DB映射方式
////创建表结构
modelBuilder.ApplyConfiguration(new StudentMap());
modelBuilder.ApplyConfiguration(new TeacherMap());
modelBuilder.ApplyConfiguration(new StudentTeacherMap());
////初始化表数据
modelBuilder.Entity().HasData(list);
modelBuilder.Entity().HasData(listTeacher);
modelBuilder.Entity().HasData(studentTeacher);
#endregion
#endregion
base.OnModelCreating(modelBuilder);
}
}
#endregion
public class PersonMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(Person));
builder.HasKey(o => o.Id);
builder.Property(o => o.Name);
builder.Property(o => o.IdCardId);
}
}
public class IdCardMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(IdCard));
builder.HasKey(o => o.Id);
//builder.Property(o => o.Name);//字段Name的类型默认是nvarchar(MAX)
builder.Property(o => o.Name).HasColumnType("varchar(20)");
builder.HasOne(o => o.Person).WithOne(o => o.IdCard).HasForeignKey(o => o.PersonId);
}
}
public class ProductMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(Product));
builder.HasKey(o => o.Id);
builder.Property(o => o.ProductName).HasColumnType("varchar(50)");
builder.HasMany(o => o.Categories).WithOne(o => o.Product);
}
}
public class CategoryMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(Category));
builder.HasKey(o => o.Id);
builder.Property(o => o.CategoryName).HasColumnType("varchar(30)");
//builder.HasOne(o => o.Product).WithMany(o => o.Categories).HasForeignKey(o => o.ProductId);
}
}
public class StudentMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(Student));
builder.HasKey(o => o.Id);
builder.Property(o => o.StudentName).HasColumnType("varchar(30)");
//builder.HasMany(o => o.StudentTeachers).WithOne(o => o.Student); //这里写这一句和在StudentTeacherMap对应关系一样的
}
}
public class TeacherMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(Teacher));
builder.HasKey(o => o.Id);
builder.Property(o => o.TeacherName).HasColumnType("varchar(33)");
//builder.HasMany(o => o.StudentTeachers).WithOne(o => o.Teacher);//这里写这一句和在StudentTeacherMap对应关系一样的
}
}
public class StudentTeacherMap : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.ToTable(nameof(StudentTeacher));
builder.HasKey(a => new { a.StudentId, a.TeacherId });
builder.HasOne(a => a.Student).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.StudentId);
builder.HasOne(a => a.Teacher).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.TeacherId);
}
}
#region EntityFrameworkCore 实体类
#region 一对一
public class Person
{
public int Id { get; set; }
public string Name { get; set; }
public int IdCardId { get; set; }
public IdCard IdCard { get; set; }
}
public class IdCard
{
public int Id { get; set; }
public string Name { get; set; }
public int PersonId { get; set; }
public Person Person { get; set; }
}
#endregion
#region 一对多
public class Product
{
public int Id { get; set; }
public string ProductName { get; set; }
public IList Categories { get; set; }
}
public class Category
{
public int Id { get; set; }
public string CategoryName { get; set; }
public int ProductId { get; set; }
public Product Product { get; set; }
}
#endregion
#region 多对多
public class Student
{
public int Id { get; set; }
public string StudentName { get; set; }
public IList StudentTeachers { get; set; }
}
public class Teacher
{
public int Id { get; set; }
public string TeacherName { get; set; }
public IList StudentTeachers { get; set; }
}
public class StudentTeacher
{
public int StudentId { get; set; }
public Student Student { get; set; }
public int TeacherId { get; set; }
public Teacher Teacher { get; set; }
}
#endregion
#endregion
}
注意：上述测试程序，需要配合数据库的使用，也就是说要先安装sqlserver或者mysql数据库，才可使用上述代码。