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<Person>(10); //testDB.Remove(person); //testDB.SaveChanges(); #endregion #region 测试一对多 //Product product = testDB.Find<Product>(10); //testDB.Remove(product); //testDB.SaveChanges(); #endregion #region 测试多对多 //Student student = testDB.Find<Student>(2); //testDB.Remove(student); //testDB.SaveChanges(); //Teacher teacher = testDB.Find<Teacher>(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<Person> Persons { get; set; }第一种EF to DB映射方式 //public DbSet<IdCard> IdCards { get; set; }第一种EF to DB映射方式 //public DbSet<Product> Products { get; set; }第一种EF to DB映射方式 //public DbSet<Category> Categorys { get; set; }第一种EF to DB映射方式 //public DbSet<Teacher> Teachers { get; set; }第一种EF to DB映射方式 //public DbSet<Student> 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<Person> list = new List<Person>(); //List<IdCard> listIdCard = new List<IdCard>(); //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<Person>() ////.HasOne(a => a.IdCard).WithOne(a => a.Person). ////HasForeignKey<IdCard>(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<Person>().HasOne(a => a.IdCard).WithOne(a => a.Person).HasForeignKey<IdCard>(a => a.PersonId); //初始化表数据 //modelBuilder.Entity<Person>().HasData(list); //modelBuilder.Entity<IdCard>().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<Person>().HasData(list); //modelBuilder.Entity<IdCard>().HasData(listIdCard); #endregion #endregion #region 一对多 ////HasData()初始化参数 //List<Product> list = new List<Product>(); //List<Category> listCategory = new List<Category>(); ////List<Category> productCategories = new List<Category>(); //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<Product>().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<Product>().HasMany(a => a.Categories).WithOne(a => a.Product); ////初始化表数据 //modelBuilder.Entity<Product>().HasData(list); //modelBuilder.Entity<Category>().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<Product>().HasData(list); //modelBuilder.Entity<Category>().HasData(listCategory); #endregion #endregion #region 多对多 //HasData()初始化参数 List<Student> list = new List<Student> { 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<Teacher> listTeacher = new List<Teacher> { 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> studentTeacher = new List<StudentTeacher> { 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<Student>().HasMany(a => a.StudentTeachers).WithOne(a => a.Student).OnDelete(DeleteBehavior.Cascade) //////modelBuilder.Entity<Teacher>().HasMany(a => a.StudentTeachers).WithOne(a => a.Teacher).OnDelete(DeleteBehavior.Cascade) //modelBuilder.Entity<Student>().HasMany(a => a.StudentTeachers).WithOne(a => a.Student); //modelBuilder.Entity<Teacher>().HasMany(a => a.StudentTeachers).WithOne(a => a.Teacher); //modelBuilder.Entity<StudentTeacher>().HasKey(a => new { a.StudentId, a.TeacherId }); ////modelBuilder.Entity<StudentTeacher>().HasOne(a => a.Student).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.StudentId); ////modelBuilder.Entity<StudentTeacher>().HasOne(a => a.Teacher).WithMany(a => a.StudentTeachers).HasForeignKey(a => a.TeacherId); //////初始化表数据 //modelBuilder.Entity<Student>().HasData(list); //modelBuilder.Entity<Teacher>().HasData(listTeacher); //modelBuilder.Entity<StudentTeacher>().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<Student>().HasData(list); modelBuilder.Entity<Teacher>().HasData(listTeacher); modelBuilder.Entity<StudentTeacher>().HasData(studentTeacher); #endregion #endregion base.OnModelCreating(modelBuilder); } } #endregion public class PersonMap : IEntityTypeConfiguration<Person> { public void Configure(EntityTypeBuilder<Person> builder) { builder.ToTable(nameof(Person)); builder.HasKey(o => o.Id); builder.Property(o => o.Name); builder.Property(o => o.IdCardId); } } public class IdCardMap : IEntityTypeConfiguration<IdCard> { public void Configure(EntityTypeBuilder<IdCard> 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<IdCard>(o => o.PersonId); } } public class ProductMap : IEntityTypeConfiguration<Product> { public void Configure(EntityTypeBuilder<Product> 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<Category> { public void Configure(EntityTypeBuilder<Category> 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<Student> { public void Configure(EntityTypeBuilder<Student> 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<Teacher> { public void Configure(EntityTypeBuilder<Teacher> 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<StudentTeacher> { public void Configure(EntityTypeBuilder<StudentTeacher> 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<Category> 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<StudentTeacher> StudentTeachers { get; set; } } public class Teacher { public int Id { get; set; } public string TeacherName { get; set; } public IList<StudentTeacher> 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。
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