internal static void Default()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
ProductCategory category = adventureWorks.ProductCategories.First();
category.Name = "Update"; // Valid value.g
ProductSubcategory subcategory = adventureWorks.ProductSubcategories.First();
subcategory.ProductCategoryID = -1; // Invalid value.
try
{
adventureWorks.SaveChanges();
}
catch (DbUpdateException exception)
{
Trace.WriteLine(exception);
// System.Data.Entity.Infrastructure.DbUpdateException: An error occurred while updating the entries. See the inner exception for details.
// ---> System.Data.Entity.Core.UpdateException: An error occurred while updating the entries. See the inner exception for details.
// ---> System.Data.SqlClient.SqlException: The UPDATE statement conflicted with the FOREIGN KEY constraint "FK_ProductSubcategory_ProductCategory_ProductCategoryID". The conflict occurred in database "D:\ONEDRIVE\WORKS\DRAFTS\CODESNIPPETS\DATA\ADVENTUREWORKS_DATA.MDF", table "Production.ProductCategory", column 'ProductCategoryID'. The statement has been terminated.
adventureWorks.Entry(category).Reload();
Trace.WriteLine(category.Name); // Accessories
adventureWorks.Entry(subcategory).Reload();
Trace.WriteLine(subcategory.ProductCategoryID); // 1
}
}
}
internal static ProductCategory Create()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
ProductCategory category = new ProductCategory()
{
Name = nameof(ProductCategory)
};
ProductSubcategory subcategory = new ProductSubcategory()
{
Name = nameof(ProductSubcategory)
};
adventureWorks.ProductSubcategories.Add(subcategory);
subcategory.ProductCategory = category;
// Equivalent to: category.ProductSubcategories.Add(subcategory);
Trace.WriteLine(adventureWorks.ChangeTracker.Entries()
.Count(tracking => tracking.State == EntityState.Added)); // 2
Trace.WriteLine(category.ProductCategoryID); // 0
Trace.WriteLine(subcategory.ProductCategoryID); // 0
Trace.WriteLine(subcategory.ProductSubcategoryID); // 0
Trace.WriteLine(adventureWorks.SaveChanges()); // 2
Trace.WriteLine(adventureWorks.ChangeTracker.Entries()
.Count(tracking => tracking.State != EntityState.Unchanged)); // 0
Trace.WriteLine(category.ProductCategoryID); // 25
Trace.WriteLine(subcategory.ProductCategoryID); // 25
Trace.WriteLine(subcategory.ProductSubcategoryID); // 50
return(category);
}
}
internal static ProductCategory Create()
{
using (AdventureWorks adventureWorks = new AdventureWorks())
{
ProductCategory category = new ProductCategory()
{
Name = "Create"
};
ProductSubcategory subcategory = new ProductSubcategory()
{
Name = "Create"
};
adventureWorks.ProductSubcategories.Add(subcategory); // Track creation.
subcategory.ProductCategory = category;
// Equivalent to: category.ProductSubcategories.Add(subcategory);
adventureWorks.ChangeTracker.Entries()
.Count(tracking => tracking.State == EntityState.Added).WriteLine(); // 2
object.ReferenceEquals(category.ProductSubcategories.Single(), subcategory).WriteLine(); // True.
category.ProductCategoryID.WriteLine(); // 0
subcategory.ProductCategoryID.WriteLine(); // 0
subcategory.ProductSubcategoryID.WriteLine(); // 0
adventureWorks.SaveChanges().WriteLine(); // 2
// BEGIN TRANSACTION
// exec sp_executesql N'SET NOCOUNT ON;
// INSERT INTO [Production].[ProductCategory] ([Name])
// VALUES (@p0);
// SELECT [ProductCategoryID]
// FROM [Production].[ProductCategory]
// WHERE @@ROWCOUNT = 1 AND [ProductCategoryID] = scope_identity();
// ',N'@p0 nvarchar(50)',@p0=N'Create'
// exec sp_executesql N'SET NOCOUNT ON;
// INSERT INTO [Production].[ProductCategory] ([Name])
// VALUES (@p0);
// SELECT [ProductCategoryID]
// FROM [Production].[ProductCategory]
// WHERE @@ROWCOUNT = 1 AND [ProductCategoryID] = scope_identity();
// ',N'@p0 nvarchar(50)',@p0=N'Create'
// COMMIT TRANSACTION
adventureWorks.ChangeTracker.Entries()
.Count(tracking => tracking.State != EntityState.Unchanged).WriteLine(); // 0
category.ProductCategoryID.WriteLine(); // 25
subcategory.ProductCategoryID.WriteLine(); // 25
subcategory.ProductSubcategoryID.WriteLine(); // 50
return(category);
} // Unit of work.
}
