public void F_RelationsEx()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.Where(x => x.Id > 20);
var alex = context.Teachers.Single(x => x.Name == "Aleksandr Kugushev");
var natalia = context.Teachers.Single(x => x.Name == "Natalia Tcvilikh");
foreach (var lesson in lessons)
{
lesson.LessonTeachers = lesson.LessonTeachers ?? new List <LessonTeacher>();
lesson.LessonTeachers.Add(new LessonTeacher {
Teacher = alex
});
if (lesson.Name == "Cloud")
{
lesson.LessonTeachers.Add(new LessonTeacher {
Teacher = natalia
});
}
}
context.SaveChanges();
}
}
public void F_RelationsWrong()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.Where(x => x.Id > 20);
var alex = new Teacher {
Id = 1, Name = "Aleksandr Kugushev"
};
var natalia = new Teacher {
Id = 2, Name = "Natalia Tcvilikh"
};
foreach (var lesson in lessons)
{
lesson.LessonTeachers = lesson.LessonTeachers ?? new List <LessonTeacher>();
lesson.LessonTeachers.Add(new LessonTeacher {
Teacher = alex
});
if (lesson.Name == "Cloud")
{
lesson.LessonTeachers.Add(new LessonTeacher {
Teacher = natalia
});
}
}
// ERROR!!!
}
}
public void F_Relations()
{
using (var context = new SamplesContext())
{
var lesson = new Lesson
{
Id = 19,
Date = new DateTime(2018, 9, 10),
Name = "ADO NET",
LessonTeachers = new List <LessonTeacher>
{
new LessonTeacher
{
Teacher = new Teacher
{
Id = 3,
Name = "Igor Pavlovskiy"
}
}
}
};
context.Add(lesson);
context.SaveChanges();
}
}
public void B_ShadowProperty()
{
using (var context = new SamplesContext())
{
var result = context.Students.Select(x => EF.Property <string>(x, "UniversityGovNum")).FirstOrDefault();
Debug.WriteLine(result);
}
}
public void E_Delete()
{
using (var context = new SamplesContext())
{
Lesson lesson = context.Lessons.Find(28);
context.Lessons.Remove(lesson);
context.SaveChanges();
}
}
public void D_Update()
{
using (var context = new SamplesContext())
{
Lesson lesson = context.Lessons.Find(22);
lesson.Date = DateTime.UtcNow;
context.SaveChanges();
}
}
public void B_SimpleExampleLin()
{
using (var context = new SamplesContext())
{
foreach (var student in context.Students.Where(x => x.UniversityDegree))
{
Debug.WriteLine($"{student.Id}; {student.Name}");
}
}
}
public void A_SimpleExample()
{
using (var context = new SamplesContext())
{
foreach (var student in context.Students)
{
Debug.WriteLine($"{student.Id}; {student.Name}");
}
}
}
public void I_OrderBy()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.OrderByDescending(x => x.Date);
foreach (var lesson in lessons)
{
Debug.WriteLine($"{lesson.Name}");
}
}
}
public void N_FromSql()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.FromSql("SELECT * FROM \"Lesson\"");
foreach (var lesson in lessons)
{
Debug.WriteLine($"{lesson.Name}");
}
}
}
public void J_GroupBy()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.GroupBy(x => x.Name);
foreach (var group in lessons)
{
Debug.WriteLine($"{group.Key} {group.Count()}");
}
}
}
public void H_DisconnectedEntites()
{
using (var context = new SamplesContext())
{
var lesson = new Lesson {
Id = 22, Date = DateTime.UtcNow, Name = "Entity Framework Core"
};
context.Update(lesson);
context.SaveChanges();
}
}
public void H_DisconnectedEntitesEx()
{
using (var context = new SamplesContext())
{
var lesson = new Lesson {
Id = 22, Date = DateTime.UtcNow, Name = "Entity Framework Hard Core"
};
var entry = context.Entry(lesson);
entry.State = EntityState.Modified;
context.SaveChanges();
}
}
public void M_Tracking()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.AsNoTracking().Where(x => x.Date < DateTime.UtcNow).ToList();
foreach (var lesson in lessons)
{
lesson.Name = "Hello World";
}
context.SaveChanges();
}
}
public void L_AsEnumerable()
{
using (var context = new SamplesContext())
{
var lessons = context.Lessons.Where(x => x.Date > DateTime.UtcNow)
.AsEnumerable()
.Where(x => x.Name.StartsWith("C"));
foreach (var lesson in lessons)
{
Debug.WriteLine($"{lesson.Name}");
}
}
}
public void G_Transactions()
{
using (var context = new SamplesContext())
{
using (var transaction = context.Database.BeginTransaction())
{
context.Lessons.Find(24).Date = new DateTime(2018, 10, 11);
context.SaveChanges();
context.Lessons.Find(25).Date = new DateTime(2018, 10, 12);
context.SaveChanges();
transaction.Commit();
}
}
}
public void K_Include()
{
List <Lesson> lessons = null;
using (var context = new SamplesContext())
{
lessons = context.Lessons
.Include(x => x.LessonTeachers)
.ThenInclude((LessonTeacher x) => x.Teacher)
.ToList();
}
foreach (var lesson in lessons)
{
foreach (var lessonTeacher in lesson.LessonTeachers)
{
Debug.WriteLine($"{lesson.Name}: {lessonTeacher.Teacher.Name}");
}
}
}
public void C_Add()
{
using (var context = new SamplesContext())
{
context.Add(new Lesson {
Id = 21, Date = new DateTime(2018, 9, 13), Name = "Net Core"
});
context.Add(new Lesson {
Id = 22, Date = new DateTime(2018, 9, 17), Name = "Entity Framework"
});
context.Add(new Lesson {
Id = 23, Date = new DateTime(2018, 9, 20), Name = "Web API"
});
context.Add(new Lesson {
Id = 24, Date = new DateTime(2018, 9, 24), Name = "Elasticsearch/Redis"
});
context.Add(new Lesson {
Id = 25, Date = new DateTime(2018, 9, 28), Name = "Docker"
});
context.Add(new Lesson {
Id = 26, Date = new DateTime(2018, 10, 1), Name = "Cloud"
});
context.Add(new Lesson {
Id = 27, Date = new DateTime(2018, 10, 4), Name = "Cloud"
});
context.Add(new Lesson {
Id = 28, Date = new DateTime(2018, 10, 5),
Name = "How to become a millionaire"
});
context.Teachers.Add(new Teacher {
Name = "Aleksandr Kugushev"
});
context.Teachers.Add(new Teacher {
Name = "Natalia Tcvilikh"
});
context.SaveChanges();
}
}
