如果只有对象的数据可以从视图模型中获得，则在linq中连接数据

我有viewModel提取多个模型类。我绑定数据，然后传递到剃刀部分视图显示数据，但我得到错误，如果一个模型对象为空。在我的业务流程中，这是预期的，但我的问题是，如果条件是Linq- Joins，即只有当数据存在于数据库中，或者有更好的方法来做，我可以使用。

 public StudentDetailedProfileViewModel GetStudentDetailedProfileByStudentID(int _studentID)
    {
        try
        {
             using (var _uow = new StudentProfile_UnitOfWork())
            {
                 StudentDetailedProfileViewModel StudentProfileObject = new StudentDetailedProfileViewModel();
                var _profile = (from _student in _uow.Student_Repository.GetAll()
                                join _contactDetail in _uow.ContactDetail_Repository.GetAll() on _student.StudentID equals _contactDetail.StudentID
                                join _addressDetail in _uow.Address_Repository.GetAll() on _student.StudentID equals _addressDetail.StudentID
                                join _studentCourse in _uow.Course_Repository.GetAll() on _student.StudentID equals _studentCourse.StudentID
                                join _school in _uow.School_Repository.GetAll() on _studentCourse.SchoolID equals _school.SchoolID
                                join _campus in _uow.Campus_Repository.GetAll() on _studentCourse.CampusID equals _campus.CampusID
                                where _student.StudentID == _studentID
                                select new StudentDetailedProfileViewModel { _studentModel = _student, _contactDetailModel = _contactDetail, _addressModel = _addressDetail , _courseModel = _studentCourse,_schoolModel = _school, _campusModel = _campus}).FirstOrDefault();
                _profile._emergencyContactModel = (from _emergencyContact in _uow.EmergencyContact_Repository.GetAll()
                                                  where _emergencyContact.StudentID == _studentID
                                                  select _emergencyContact).ToList();

                return _profile;                
            }
        }//
        catch { return null; }
    }

……

public class StudentDetailedProfileViewModel
{
    public StudentDetailedProfileViewModel() { }
    public Student _studentModel { get; set; }
    public Course _courseModel { get; set; }
    public School _schoolModel { get; set; }
    public Campus _campusModel { get; set; }
    public ContactDetail _contactDetailModel { get; set; }
    public Address _addressModel { get; set; }
    public List<EmergencyContact> _emergencyContactModel { get; set; }
}