public static void UpdateOneToOneEntity()
{
Student stud;
// Get student from DB
using (var ctx = new SchoolDBEntities())
{
stud = ctx.Students.Include(s => s.StudentAddress).Where(s => s.StudentID == 1).FirstOrDefault <Student>();
}
// change student name in disconnected mode (out of context scope)
if (stud != null)
{
stud.StudentName = "updated student";
if (stud.StudentAddress == null)
{
stud.StudentAddress = new StudentAddress();
stud.StudentAddress.StudentID = stud.StudentID;
stud.StudentAddress.Address1 = "address444";
stud.StudentAddress.Address2 = "add222";
stud.StudentAddress.City = "city444";
stud.StudentAddress.State = "State444";
}
else if (stud.StudentAddress != null) // delete address
{
stud.StudentAddress = null;
}
}
//save modified entity using new context
using (var dbCtx = new SchoolDBEntities())
{
StudentAddress existingStudentAddress = dbCtx.StudentAddresses.Where(addr => addr.StudentID == stud.StudentID).FirstOrDefault <StudentAddress>();
//Mark each entity as modified
dbCtx.Entry(stud).State = System.Data.EntityState.Modified;
//dbCtx.Entry(stud.StudentAddress).State = System.Data.EntityState.Modified;
if (existingStudentAddress != null)
{
dbCtx.Entry <StudentAddress>(existingStudentAddress).State = System.Data.EntityState.Deleted;
if (stud.StudentAddress != null)
{
dbCtx.StudentAddresses.Add(stud.StudentAddress);
}
}
else
{
dbCtx.StudentAddresses.Add(stud.StudentAddress);
}
if (dbCtx.GetValidationErrors().Count() <= 0)
{
dbCtx.SaveChanges();
}
}
Console.WriteLine("UpdateOneToOneEntity successfull");
}
public static void UpdateOneToManyEntity()
{
Student stud;
// Get student from DB
using (var ctx = new SchoolDBEntities())
{
ctx.Configuration.ProxyCreationEnabled = false;
stud = ctx.Students.Where(s => s.StudentID == 1).Include(s => s.Standard.Teachers).FirstOrDefault <Student>();
}
var teachers = stud.Standard.Teachers.ToList <Teacher>();
foreach (Teacher tchr in teachers)
{
tchr.TeacherName = "Updated " + tchr.TeacherName;
}
//add new teacher
teachers.Add(new Teacher()
{
TeacherName = "New teacher4"
});
teachers.Add(new Teacher()
{
TeacherName = "New teacher5"
});
teachers.RemoveAt(1);
using (var dbCtx = new SchoolDBEntities())
{
//Get fresh data from database
var existingStudent = dbCtx.Students.AsNoTracking().Include(s => s.Standard).Include(s => s.Standard.Teachers).Where(s => s.StudentID == stud.StudentID).FirstOrDefault <Student>();
var existingTeachers = existingStudent.Standard.Teachers.ToList <Teacher>();
var updatedTeachers = teachers.ToList <Teacher>();
//Find newly added teachers by updatedTeachers - existingTeacher = newly added teacher
var addedTeachers = updatedTeachers.Except(existingTeachers, tchr => tchr.TeacherId);
//Find deleted teachers by existing teachers - updatedTeachers = deleted teachers
var deletedTeachers = existingTeachers.Except(updatedTeachers, tchr => tchr.TeacherId);
//Find modified teachers by updatedTeachers - addedTeachers = modified teachers
var modifiedTeacher = updatedTeachers.Except(addedTeachers, tchr => tchr.TeacherId);
//Mark all added teachers entity state to Added
addedTeachers.ToList <Teacher>().ForEach(tchr => dbCtx.Entry(tchr).State = System.Data.EntityState.Added);
//Mark all deleted teacher entity state to Deleted
deletedTeachers.ToList <Teacher>().ForEach(tchr => dbCtx.Entry(tchr).State = System.Data.EntityState.Deleted);
//Apply modified teachers current property values to existing property values
foreach (Teacher teacher in modifiedTeacher)
{
//Find existing teacher by id from fresh database teachers
var existingTeacher = dbCtx.Teachers.Find(teacher.TeacherId);
if (existingTeacher != null)
{
//Get DBEntityEntry object for each existing teacher entity
var teacherEntry = dbCtx.Entry(existingTeacher);
//overwrite all property current values from modified teachers' entity values,
//so that it will have all modified values and mark entity as modified
teacherEntry.CurrentValues.SetValues(teacher);
}
}
//Save all above changed entities to the database
dbCtx.SaveChanges();
}
Console.WriteLine("UpdateOneToOneEntity successfull");
}
