static void IqueryableExample()
{
var context = new PlutoContext();
IQueryable <Course> courses = context.Courses;
var filtered = courses.Where(c => c.Level == 1);
}
static void Linq()
{
var context = new PlutoContext();
// LINQ syntax
Console.WriteLine("LINQ syntax...");
var query =
from c in context.Courses
where c.Name.Contains("c#")
orderby c.Name
select c;
foreach (var course in query)
{
Console.WriteLine(course.Name);
}
// Extension methods
Console.WriteLine("Extension methods...");
var courses = context.Courses
.Where(c => c.Name.Contains("c#"))
.OrderBy(c => c.Name);
foreach (var course in courses)
{
Console.WriteLine(course.Name);
}
}
static void Linq2()
{
var context = new PlutoContext();
// Simple
var query =
from c in context.Courses
where c.Author.Id == 1
orderby c.Level descending, c.Name
select new { Name = c.Name, Author = c.Author.Name };
// Grouping
var query2 =
from c in context.Courses
group c by c.Level
into g
select g;
foreach (var group in query2)
{
Console.WriteLine("{0} ({1})", group.Key, group.Count());
foreach (var course in group)
{
Console.WriteLine("\t{0}", course.Name);
}
}
// Joining
var query3 =
from c in context.Courses
join a in context.Authors on c.AuthorId equals a.Id
select new { CourseName = c.Name, AuthorName = a.Name };
// Group join - left join
var query4 =
from a in context.Authors
join c in context.Courses on a.Id equals c.AuthorId into g
select new { AuthorName = a.Name, Courses = g.Count() };
foreach (var x in query4)
{
Console.WriteLine("{0} ({1})", x.AuthorName, x.Courses);
}
// cross join
var query5 =
from a in context.Authors
from c in context.Courses
select new { AuthorName = a.Name, CourseName = c.Name };
foreach (var x in query5)
{
Console.WriteLine("{0} ({1})", x.AuthorName, x.CourseName);
}
}
static void RemoveData()
{
var context = new PlutoContext();
var course = context.Courses.Find(6);
context.Courses.Remove(course);
context.SaveChanges();
}
static void UpdateData()
{
var context = new PlutoContext();
var course = context.Courses.Find(1);
course.Name = "New course name";
course.AuthorId = 2;
context.SaveChanges();
}
static void LazyLoading()
{
var context = new PlutoContext();
var courses = context.Courses.ToList();
foreach (var course in courses)
{
Console.WriteLine("{0} by {1}", course.Name, course.Author.Name);
}
}
static void Deffered()
{
var context = new PlutoContext();
var courses = context.Courses;
var filtered = courses.Where(c => c.Level == 1);
var sorted = filtered.OrderBy(c => c.Name);
foreach (var c in courses)
{
Console.WriteLine(c.Name);
}
}
static void EagerLoading()
{
var context = new PlutoContext();
// var courses = context.Courses.Include("Author").ToList(); // bad practice
var courses = context.Courses.Include(c => c.Author).ToList();
foreach (var course in courses)
{
Console.WriteLine("{0} by {1}", course.Name, course.Author.Name);
}
//context.Courses.Include(c => c.Author.Address);
//context.Courses.Include(a => a.Tags.Select(t => t.Name));
}
static void ExplicitLoading()
{
var context = new PlutoContext();
var author = context.Authors.Single(a => a.Id == 1);
// MSDN way
context.Entry(author).Collection(a => a.Courses).Query().Where(c => c.FullPrice == 0).Load();
// Desired way
context.Courses.Where(c => c.AuthorId == author.Id && c.FullPrice == 0).Load();
foreach (var course in author.Courses)
{
Console.WriteLine("{0}", course.Name);
}
}
static void AddingData()
{
var context = new PlutoContext();
var author = context.Authors.Single(a => a.Id == 1);
var course = new Course
{
Name = "New Course",
Description = "New Description",
FullPrice = 19.95f,
Level = 1,
Author = author
};
context.Courses.Add(course);
context.SaveChanges();
}
static void ChangeTracker()
{
var context = new PlutoContext();
context.Authors.Add(new Author {
Name = "New Author"
});
var author = context.Authors.Find(3);
author.Name = "Updated";
var another = context.Authors.Find(4);
context.Authors.Remove(another);
var entries = context.ChangeTracker.Entries();
foreach (var entry in entries)
{
entry.Reload();
Console.WriteLine(entry.State);
}
}
static void ExtensionMethods()
{
var context = new PlutoContext();
// Simples
var courses = context.Courses
.Where(c => c.Level == 1)
.OrderByDescending(c => c.Name).ThenBy(c => c.Level)
.Select(c => new { CourseName = c.Name, AuthorName = c.Author.Name });
var tags = context.Courses
.Where(c => c.Level == 1)
.OrderByDescending(c => c.Name).ThenBy(c => c.Level)
.SelectMany(c => c.Tags)
.Distinct();
// Groups
var groups = context.Courses.GroupBy(c => c.Level);
foreach (var group in groups)
{
Console.WriteLine("Key: " + group.Key);
foreach (var course in group)
{
Console.WriteLine("\t" + course.Name);
}
}
// Join
context.Courses.Join(context.Authors,
c => c.AuthorId,
a => a.Id,
(course, author) => new
{
CourseName = course.Name,
AuthorName = author.Name
});
// Group Join
context.Authors.GroupJoin(context.Courses,
a => a.Id,
c => c.AuthorId,
(author, coursesList) => new
{
Author = author.Name,
Courses = coursesList.Count()
});
// Cross join
context.Authors.SelectMany(a => context.Courses,
(author, course) => new
{
AuthorName = author.Name,
CourseName = course.Name
});
// Partitioning
context.Courses.Skip(10).Take(10);
// Element Operators
context.Courses.OrderBy(c => c.Level).FirstOrDefault(c => c.FullPrice > 100);
context.Courses.OrderBy(c => c.Level).SingleOrDefault(c => c.Id == 1);
// Quantifing
bool r = context.Courses.All(c => c.Level == 1);
r = context.Courses.Any(c => c.Level == 1);
// Aggregating
context.Courses.Count();
context.Courses.Max(c => c.FullPrice);
context.Courses.Min(c => c.FullPrice);
context.Courses.Average(c => c.FullPrice);
}
