public static void Run()
{
using (var db = new BloggingContext())
{
db.Database.EnsureDeleted();
db.Database.EnsureCreated();
db.Blogs.Add(new Blog
{
Url = "http://sample.com",
Posts = new List<Post>
{
new Post { Title = "Saving Data with EF" },
new Post { Title = "Cascade Delete with EF" }
}
});
db.SaveChanges();
}
using (var db = new BloggingContext())
{
var blog = db.Blogs.Include(b => b.Posts).First();
db.Remove(blog);
db.SaveChanges();
}
using (var db = new BloggingContext())
{
db.Blogs.Add(new Blog
{
Url = "http://sample.com",
Posts = new List<Post>
{
new Post { Title = "Saving Data with EF" },
new Post { Title = "Cascade Delete with EF" }
}
});
db.SaveChanges();
}
using (var db = new BloggingContext())
{
var blog = db.Blogs.First();
db.Remove(blog);
db.SaveChanges();
}
}
private static void DeleteOrphansSample(DeleteBehavior deleteBehavior, bool requiredRelationship)
{
Console.WriteLine(
$"Test deleting orphans with DeleteBehavior.{deleteBehavior} and {(requiredRelationship ? "a required" : "an optional")} relationship:");
InitializeDatabase(requiredRelationship);
using var context = new BloggingContext(deleteBehavior, requiredRelationship);
#region DeleteOrphansVariations
var blog = context.Blogs.Include(b => b.Posts).First();
var posts = blog.Posts.AsQueryable().ToList();
DumpEntities(" After loading entities:", context, blog, posts);
blog.Posts.Clear();
DumpEntities(" After making posts orphans:", context, blog, posts);
try
{
Console.WriteLine();
Console.WriteLine(" Saving changes:");
context.SaveChanges();
DumpSql();
DumpEntities(" After SaveChanges:", context, blog, posts);
}
catch (Exception e)
{
DumpSql();
Console.WriteLine();
Console.WriteLine(
$" SaveChanges threw {e.GetType().Name}: {(e is DbUpdateException ? e.InnerException.Message : e.Message)}");
}
#endregion
Console.WriteLine();
}
private static void DeleteBehaviorSample(DeleteBehavior deleteBehavior, bool requiredRelationship)
{
Console.WriteLine(
$"Test using DeleteBehavior.{deleteBehavior} with {(requiredRelationship ? "required" : "optional")} relationship:");
InitializeDatabase(requiredRelationship);
using var context = new BloggingContext(deleteBehavior, requiredRelationship);
#region DeleteBehaviorVariations
var blog = context.Blogs.Include(b => b.Posts).First();
var posts = blog.Posts.ToList();
DumpEntities(" After loading entities:", context, blog, posts);
context.Remove(blog);
DumpEntities($" After deleting blog '{blog.BlogId}':", context, blog, posts);
try
{
Console.WriteLine();
Console.WriteLine(" Saving changes:");
context.SaveChanges();
DumpSql();
DumpEntities(" After SaveChanges:", context, blog, posts);
}
catch (Exception e)
{
DumpSql();
Console.WriteLine();
Console.WriteLine(
$" SaveChanges threw {e.GetType().Name}: {(e is DbUpdateException ? e.InnerException.Message : e.Message)}");
}
#endregion
Console.WriteLine();
}
private static void InitializeDatabase(bool requiredRelationship)
{
using var context = new BloggingContext(DeleteBehavior.ClientSetNull, requiredRelationship);
context.Database.EnsureDeleted();
context.Database.EnsureCreated();
context.Blogs.Add(
new Blog
{
Url = "http://sample.com",
Posts = new List <Post> {
new Post {
Title = "Saving Data with EF"
}, new Post {
Title = "Cascade Delete with EF"
}
}
});
context.SaveChanges();
}