我正在使用ModelBuilder将现有数据库映射到POCO。我有课程,学生和会议。这是表格
CREATE TABLE Courses (
CourseID int,
Name string)
CREATE TABLE Students(
StudentID int,
Name string)
CREATE TABLE Courses_Students (
CourseID int,
StudentID int)
CREATE TABLE Meetings (
MeetingID int,
CourseID int,
MeetDate datetime)
和POCO
public class Course {
public int CourseID { get; set; }
public string Name { get; set; }
public virtual ICollection<CourseMeeting> Meetings { get; set; }
public virtual ICollection<Student> Students { get; set; }
}
public class Student {
public int StudentID { get; set; }
public string Name { get; set; }
}
public class Meeting {
public int MeetingID { get; set; }
public int CourseID { get; set; }
public DateTime MeetDate { get; set; }
}
表格映射效果很好:
modelBuilder.Entity<Course>().MapSingleType().ToTable("Courses");
modelBuilder.Entity<Student>().MapSingleType().ToTable("Students");
modelBuilder.Entity<Meeting>().MapSingleType().ToTable("Meetings");
使用连接表并且没有导航属性的多对多映射有效(即WithMany()
上没有指定Students.Courses属性)
modelBuilder.Entity<Course>()
.HasMany(c => c.Students)
.WithMany()
.Map(StoreTableName.FromString("Courses_Students"),
(c, s) => new { CourseID = c.CourseID, StudentID = s.StudentID});
但是我在映射没有连接表的其他关系时遇到了问题。这显然是不对的:
modelBuilder.Entity<Course>().HasMany(c => c.Meetings).WithMany();
因为它想要一个连接表:Invalid object name 'dbo.Course_Meetings'
。我可以向Course
对象添加Meeting
属性,然后使用
modelBuilder.Entity<Course>()
.HasMany(c => c.Meetings)
.WithOptional(m => m.Course)
.HasConstraint((c, m) => c.CoursID == me.CourseID);
但我想在没有导航属性的情况下这样做。 EF4和现有数据库是否可以实现这一目标?
答案 0 :(得分:1)
假设它需要连接表(并因此寻找它),因为你没有在原始声明中映射属性。
尝试手动映射实际表上的属性,如下所示..
public class Meeting {
public int MeetingID { get; set; }
public int CourseID { get; set; }
public DateTime MeetDate { get; set; }
public Course { get; set; }
}
然后按如下方式配置:
modelBuilder.Entity<Meeting>(m => new {
MeetingId = m.Meeting,
MeetDate = m.MeetDate,
CourseId = m.Course.Id
})
.HasRequired(m => m.Course)
.WithMany()