让孩子和父母一起

Question

考虑以下两个类School 和Student。学校收集了学生。学生也与未映射的学校相关联

public class School
{
    public int Id { get; set; }
    public virtual ICollection<Student> students { get; set; }
}

public class Student
{
    public int Id { get; set; }
    public int SchoolId { get; set; }
    public string Name { get; set; }
    public bool Deleted { get; set; }
    public virtual School School { get; set; }
}

我的模型构建器看起来像这样

modelBuilder.Entity<School>()
        .HasMany(obj => obj.students)
        .WithOne()
        .HasForeignKey(obj => obj.SchoolId)
        .OnDelete(DeleteBehavior.Cascade)
        .IsRequired();

modelBuilder.Entity<Student>(entity =>
{
    entity.HasOne(e => e.School);
});

什么有效 -

var result = mydbcontext.Schools
                        .Include(d => d.students)
                        .Where(d => d.Id == 1)
                        .Select(x => new School
                        {
                            Id = x.Id,
                            students = x.students.Where(s => !s.Deleted).ToList()
                        })
                        .AsNoTracking()
                        .ToList();

什么不工作 -

var school = mydbcontext.Students
                        .Include(x => x.School) //returning null
                        .Where(s => !s.Deleted)
                        .ToList();

当我尝试上面的代码时，我得到了所有没有被删除的学生，但是我得到了 Empty 学校的结果

我这里有什么遗漏吗？

Answer 1

这看起来很可能是由 Student 类 School 属性上的 [NotMapped] 属性引起的。使用该属性指示 EF 不要在数据库中创建对应的列来将 Student 记录键入回 School 记录，因此 EF 将无法推断 Student->Schoolrelationship，只有School->Students 关系。