c# - join data in linq if only data for object is available from view model - ASP.net -mvc5 -

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i have viewmodel extract of multiple model classes. binding data , passing razor partial view show data getting error if 1 of model object null. in business process expected question can use if condition linq--joins i.e. join result if data exist in database or there better way it.

 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                                 _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()                                                   _emergencycontact.studentid == _studentid                                                   select _emergencycontact).tolist();                   return _profile;                             }         }//         catch { return null; }      }

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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; }  }

instead of joining, if root entity (student) has navigation properties child collections (and associations configured in entity model) include() them. let linq generate select statement rather trying figure out beforehand.


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