Esempio n. 1
0
        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");
        }
Esempio n. 2
0
        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");
        }