1. 基本引用模式：
this.Has****** (p=>p.AAA).With******() // ******有这几个可选值：
- Optional 可选（0或1个）
- Required有且只有一个（1个）
- Many（多个）
2. 一对多关系配置：
基本的插入查询(建立好外键约束)：
public class Student
{
public long ID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public virtual Class cls { get; set; }
public long classId { get; set; }
}
public class Class
{
public long ID { get; set; }
public string Name { get; set; }
}
插入数据：
using (TestDBContent tdc = new TestDBContent())
{
Class cls = new Class() { Name="测试1班"};
tdc.Classes.Add(cls);
Student stu = new Student() {
Age=18,
cls=cls,
Name="风雪幻林"
};
tdc.students.Add(stu);
tdc.SaveChanges();
}
2.1 不要设计双向关系:
public class Class
{
public long ID { get; set; }
public string Name { get; set; }
public ICollection<Student> students { get; set; }
}
查询数据：
Class clz = tdc.Classes.First();
var stus = tdc.students.Where(i => i.classId == clz.ID);
foreach (var item in stus)
{
Console.WriteLine(item.Name);
}
2.2 通过Fluent API做配置:
- 在一对多的表中（多的一端做配置）
this. HasRequired(s=> s.Class).WithMany() .HasForeignKey(s => s.ClassId) - 找不到 Class_Id 字段
需要在 ClassConfig 中再反向配置一遍
3. 多对多关系配置：
- 推荐配置：
public class Student
{
public Student()
{
teachers = new List<Teacher>();
}
public long ID { get; set; }
public string Name { get; set; }
public int Age { get; set; }
public virtual ICollection<Teacher> teachers { get; set; }
}
public class Teacher
{
public Teacher()
{
students = new List<Student>();
}
public long ID { get; set; }
public string Name { get; set; }
public virtual ICollection<Student> students { get; set; }
}
- Fluent API 多对多的配置：
- 在其中一端配置
public class TeacherConfig : EntityTypeConfiguration<Teacher>
{
public TeacherConfig()
{
this.ToTable("t_class");
this.Property(e => e.Name).HasMaxLength(30).IsRequired();
this.HasMany(e=>e.students).WithMany(i=>i.teachers).Map(m=>m.ToTable("t_teacherstudent").MapLeftKey("techerId").MapRightKey("studentId"));
}
}
public class StudentConfig : EntityTypeConfiguration<Student>
{
public StudentConfig()
{
this.ToTable("t_student");
}
}
- 调用：
static void Main(string[] args)
{
Teacher t = new Teacher() { Name = "语文老师" };
Teacher t2 = new Teacher() { Name = "数学老师" };
Student s = new Student() { Name = "张三", Age = 21 };
Student s2 = new Student() { Name = "李四", Age = 22 };
using (TestDBContent tdb =new TestDBContent ())
{
t.students.Add(s);
t.students.Add(s2);
t2.students.Add(s);
t2.students.Add(s2);
tdb.teachers.Add(t);
tdb.teachers.Add(t2);
tdb.SaveChanges();
}
Console.WriteLine("ok");
Console.ReadKey();
}
- 多对多的关系：
- 移除关系： t.Students.Remove(t.Students.First())
