public static void AddTagsToVideo(int videoId, params string[] tagNames)
{
using (var context = new VidAppContext())
{
// Mit LINQ:
// SELECT FROM Tags WHERE Name IN ('classics', 'drama')
var tags = context.Tags.Where(t => tagNames.Contains(t.Name)).ToList();
foreach (var tagName in tagNames)
{
if (!tags.Any(t => t.Name.Equals(tagName, StringComparison.CurrentCultureIgnoreCase)))
{
tags.Add(new Tag {
Name = tagName
});
}
}
var video = context.Videos.Single(v => v.Id == videoId);
tags.ForEach(t => video.AddTag(t));
context.SaveChanges();
}
}
public static void AddVideo(Video video)
{
using (var context = new VidAppContext())
{
context.Videos.Add(video);
context.SaveChanges();
}
}
static void Main(string[] args)
{
using (var context = new VidAppContext()) {
context.Database.Log = Console.WriteLine;
context.AddVideo("Video 4", DateTime.Today, "Horror", (byte)Classification.Gold);
}
}
public static void RemoveVideo(int videoId)
{
using (var context = new VidAppContext())
{
var video = context.Videos.SingleOrDefault(v => v.Id == videoId);
if (video == null)
{
return;
}
context.Videos.Remove(video);
context.SaveChanges();
}
}
public static void RemoveTagsFromVideo(int videoId, params string[] tagNames)
{
using (var context = new VidAppContext())
{
context.Tags.Where(t => tagNames.Contains(t.Name)).Load();
var video = context.Videos.Single(v => v.Id == videoId);
foreach (var tagName in tagNames)
{
// Wir haben die Logik für das Entfernen von Tags in der Video-Klasse gekapselt.
// Das ist sauberes OO. Die Video-Klasse soll verantwortlich sein, um Tags
// um Tags zu ihrer Liste hinzuzufügen bzw. zu entfernen.
video.RemoveTag(tagName);
}
context.SaveChanges();
}
}
public static void RemoveGenre(int genreId, bool enforceDeletingVideos)
{
using (var context = new VidAppContext())
{
var genre = context.Genres.Include(g => g.Videos).SingleOrDefault(g => g.Id == genreId);
if (genre == null)
{
return;
}
if (enforceDeletingVideos)
{
context.Videos.RemoveRange(genre.Videos);
}
context.Genres.Remove(genre);
context.SaveChanges();
}
}
static void Main(string[] args)
{
// Um LazyLoading zu aktivieren, müssen die Navigation-Properties als virtual definiert werden,
// damit EF ein Proxy erstellen kann.
using (var context = new VidAppContext()) {
context.Database.Log = Console.WriteLine;
var videos = context.Videos.ToList();
Console.WriteLine();
Console.WriteLine("LAZY LOADING");
foreach (var v in videos)
{
Console.WriteLine("{0} ({1})", v.Name, v.Genre.Name);
}
// Eager loading
var videosWithGenres = context.Videos.Include(v => v.Genre).ToList();
Console.WriteLine();
Console.WriteLine("EAGER LOADING");
foreach (var v in videosWithGenres)
{
Console.WriteLine("{0} ({1})", v.Name, v.Genre.Name);
}
// Explicit loading
// NOTE: At this point, genres are already loaded into the context,
// so the following line is not going to make a difference. If you
// want to see expicit loading in action, comment out the eager loading
// part as well as the foreach block in the lazy loading.
context.Genres.Load();
Console.WriteLine();
Console.WriteLine("EXPLICIT LOADING");
foreach (var v in videos)
{
Console.WriteLine("{0} ({1})", v.Name, v.Genre.Name);
}
}
}
public static void AddTags(params string[] tagNames)
{
using (var context = new VidAppContext())
{
// Wir laden die Tags vorgängig um Duplikate zu vermeiten
var tags = context.Tags.Where(t => tagNames.Contains(t.Name)).ToList();
foreach (var name in tagNames)
{
if (!tags.Any(t => t.Name.Equals(name, StringComparison.CurrentCultureIgnoreCase)))
{
context.Tags.Add(new Tag {
Name = name
});
}
}
context.SaveChanges();
}
}
static void Main(string[] args)
{
using (var context = new VidAppContext()) {
context.Database.Log = Console.WriteLine;
// Aufgabe 1: Actionfilme sortiert nach Name
Console.WriteLine();
Console.WriteLine("ACTION MOVIES SORTED BY NAME");
var actionMovies = context.Videos
.Where(v => v.Genre.Name == "Action")
.OrderBy(v => v.Name);
foreach (var v in actionMovies)
{
Console.WriteLine(v.Name);
}
// Aufgabe 2: Gold Drama File sortiert nach Erscheinungsdatum (ReleaseDate). Neuster Film zuerst.
var dramaMovies = context.Videos
.Where(v => v.Genre.Name == "Drama" && v.Classification == Classification.Gold)
.OrderByDescending(v => v.ReleaseDate);
Console.WriteLine();
Console.WriteLine("GOLD DRAMA MOVIES SORTED BY RELEASE DATE (NEWEST FIRST)");
foreach (var v in dramaMovies)
{
Console.WriteLine(v.Name);
}
// Aufgabe 3: Alle Filme projiziert in einen anonymen Typ
var projected = context.Videos
.Select(v => new { MovieName = v.Name, Genre = v.Genre.Name });
Console.WriteLine();
Console.WriteLine("ALL MOVIES PROJECTED INTO AN ANONYMOUS TYPE");
foreach (var v in projected)
{
Console.WriteLine(v.MovieName);
}
// Aufgabe 4: Alle Filme gruppiert nach Classification
var groups = context.Videos
.GroupBy(v => v.Classification)
.Select(g => new {
Classification = g.Key.ToString(),
Videos = g.OrderBy(v => v.Name)
});
Console.WriteLine();
Console.WriteLine("ALL MOVIES GROUPED BY CLASSIFICATION");
foreach (var g in groups)
{
Console.WriteLine("Classification: " + g.Classification);
foreach (var v in g.Videos)
{
Console.WriteLine("\t" + v.Name);
}
}
// Aufgabe 5: Classifications and Anzahl Videos
var classifications = context.Videos
.GroupBy(v => v.Classification)
.Select(g => new {
Name = g.Key.ToString(),
VideosCount = g.Count()
})
.OrderBy(c => c.Name);
Console.WriteLine();
Console.WriteLine("CLASSIFICATIONS AND NUMBER OF VIDEOS IN THEM");
foreach (var c in classifications)
{
Console.WriteLine("{0} ({1})", c.Name, c.VideosCount);
}
// Aufgabe 6: Genres and Anzahl Videos
var genres = context.Genres
.GroupJoin(context.Videos, g => g.Id, v => v.GenreId, (genre, videos) => new {
Name = genre.Name,
VideosCount = videos.Count()
})
.OrderByDescending(g => g.VideosCount);
Console.WriteLine();
Console.WriteLine("GENRES AND NUMBER OF VIDEOS IN THEM");
foreach (var g in genres)
{
Console.WriteLine("{0} ({1})", g.Name, g.VideosCount);
}
}
}
