internal static void Attach()
{
Product product = new UniversalProduct()
{
Name = "On the fly", ListPrice = 1
};
using (AdventureWorks adventureWorks = new AdventureWorks())
{
product.ListPrice = 2;
Trace.WriteLine(adventureWorks.GetChangeSet().Updates.Any()); // False.
adventureWorks.Products.Attach(product);
product.ListPrice = 3;
adventureWorks.GetChangeSet().Updates.OfType <Product>().ForEach(attached => Trace.WriteLine(
$"{adventureWorks.Products.GetOriginalEntityState(attached).ListPrice} -> {attached.ListPrice}")); // 2 -> 3.
}
}
internal static void UpdateWithNoChange()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
Product product = adventureWorks.Find <Product>(999);
product.ListPrice += product.ListPrice;
product.ListPrice /= 2; // Change tracked entity then change back.
Trace.WriteLine(adventureWorks.GetChangeSet().Updates.Any()); // False.
adventureWorks.SubmitChanges();
}
}
internal static void DisableObjectTracking()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
adventureWorks.ObjectTrackingEnabled = false;
Product product = adventureWorks.Products.First();
product.ListPrice += 100;
Trace.WriteLine(adventureWorks.GetChangeSet().Updates.Any()); // False
adventureWorks.ObjectTrackingEnabled = true;
// System.InvalidOperationException: Data context options cannot be modified after results have been returned from a query.
}
}
internal static void RelationshipChanges()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
DataLoadOptions loadOptions = new DataLoadOptions();
loadOptions.LoadWith <ProductCategory>(entity => entity.ProductSubcategories);
adventureWorks.LoadOptions = loadOptions;
ProductCategory category = adventureWorks.ProductCategories.First();
Trace.WriteLine(category.ProductSubcategories.Count); // 12.
ProductSubcategory[] subcategories = category.ProductSubcategories.ToArray();
Trace.WriteLine(subcategories.All(subcategory => subcategory.ProductCategory == category)); // True.
category.ProductSubcategories.Clear();
Trace.WriteLine(category.ProductSubcategories.Count); // 0.
Trace.WriteLine(adventureWorks.GetChangeSet().Updates.Count); // 12.
Trace.WriteLine(subcategories.All(subcategory => subcategory.ProductCategory == null)); // True.
}
}
internal static void EntityChanges()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
Product insert = new UniversalProduct()
{
Name = "Insert", ListPrice = 123
};
// Product insert = new Product() causes InvalidOperationException for InsertOnSubmit:
// InvalidOperationException: Instance of type 'Tutorial.LinqToSql.Product' could not be added. This type is not part of the mapped type system.
adventureWorks.Products.InsertOnSubmit(insert);
IQueryable <Product> update = adventureWorks.Products
.Where(product => product.Name.Contains("HL"));
update.ForEach(product => product.ListPrice += 50);
IQueryable <Product> delete = adventureWorks.Products
.Where(product => product.Name.Contains("ML"));
adventureWorks.Products.DeleteAllOnSubmit(delete);
ChangeSet changeSet = adventureWorks.GetChangeSet();
Trace.WriteLine(changeSet.Inserts.Any()); // True.
Trace.WriteLine(changeSet.Updates.Any()); // True.
Trace.WriteLine(changeSet.Deletes.Any()); // True.
changeSet.Inserts.OfType <Product>().ForEach(product => Trace.WriteLine(
$"{nameof(ChangeSet.Inserts)}: ({product.ProductID}, {product.Name}, {product.ListPrice})"));
changeSet.Updates.OfType <Product>().ForEach(product =>
{
Product original = adventureWorks.Products.GetOriginalEntityState(product);
Trace.WriteLine($"{nameof(ChangeSet.Updates)}: ({original.ProductID}, {original.Name}, {original.ListPrice}) -> ({product.ProductID}, {product.Name}, {product.ListPrice})");
});
changeSet.Deletes.OfType <Product>().ForEach(product => Trace.WriteLine(
$"{nameof(ChangeSet.Deletes)}: ({product.ProductID}, {product.Name}, {product.ListPrice})"));
// Inserts: (0, Insert, 123)
// Updates: (951, HL Crankset, 404.9900) -> (951, HL Crankset, 454.9900)
// Updates: (996, HL Bottom Bracket, 121.4900) -> (996, HL Bottom Bracket, 171.4900)
// Deletes: (950, ML Crankset, 256.4900)
// Deletes: (995, ML Bottom Bracket, 101.2400)
}
}