static void ChangeMovie()
{
using (var db = new MoviesDBContext())
{
// get the first movie by name
// this entity is tracked.
var movie = db.Movie.OrderBy(m => m.Name).First();
// edit it
movie.Name = "Solo";
// create (untracked) genre entity
var genre = new Genre {
Name = "Action/Adventure"
};
// begin tracking it as an "added" entity
//db.Add(genre);
movie.Genre = genre;
// the new genre gets added to the db because the movie
// referencing it is tracked.
// make sure that we are tracking all changes for this object
// (if it's untracked, start tracking it)
db.Update(movie);
// update the database, picking up tracked changes.
db.SaveChanges();
}
}
public async Task <IActionResult> Edit(int id, [Bind("Id,Title,ReleaseDate,Genre,Price")] Movie movie)
{
if (id != movie.Id)
{
return(NotFound());
}
if (ModelState.IsValid)
{
try
{
_context.Update(movie);
await _context.SaveChangesAsync();
}
catch (DbUpdateConcurrencyException)
{
if (!MovieExists(movie.Id))
{
return(NotFound());
}
else
{
throw;
}
}
return(RedirectToAction(nameof(Index)));
}
return(View(movie));
}
static void EarlierCode()
{
PrintMovies();
ChangeMovie();
PrintMovies();
var movie = new Movie {
Id = 1, Name = "Toy Story", GenreId = 1
};
// at this point, movie is untracked.
using (var db = new MoviesDBContext())
{
// begin tracking the movie, based on the Id it has.
// treat any difference as updates to be made.
db.Update(movie);
// push the changes to the db
db.SaveChanges();
}
}