private static void ConflictingUpdateLastWins()
{
NorthwindEntities context = new NorthwindEntities();
Category newCategory = new Category()
{
CategoryName = "New Category",
Description = "New category, just for testing"
};
context.Categories.Add(newCategory);
context.SaveChanges();
// This context works in different transaction
NorthwindEntities anotherContext = new NorthwindEntities();
Category lastCategory =
(from cat in anotherContext.Categories
where cat.CategoryID == newCategory.CategoryID
select cat).First();
lastCategory.CategoryName = lastCategory.CategoryName + " 2";
anotherContext.SaveChanges();
// This will cause OptimisticConcurrencyException if
// Categories.CategoryName has ConcurrencyMode=Fixed
newCategory.CategoryName = newCategory.CategoryName + " 3";
// Database wins
bool isFailed;
do
{
isFailed = false;
try
{
context.SaveChanges();
}
catch (DbUpdateConcurrencyException ex)
{
isFailed = true;
ex.Entries.Single().Reload();
}
} while (isFailed);
// Client wins
//bool isFailed;
//do
//{
// isFailed = false;
// try
// {
// context.SaveChanges();
// }
// catch (DbUpdateConcurrencyException ex)
// {
// isFailed = true;
// var entry = ex.Entries.Single();
// entry.OriginalValues.SetValues(entry.GetDatabaseValues());
// }
//} while (isFailed);
}
private static void AddCategoriesInTransaction()
{
NorthwindEntities context = new NorthwindEntities();
// Add a valid new category
Category newCategory = new Category()
{
CategoryName = "New Category",
Description = "New category, just for testing"
};
context.Categories.Add(newCategory);
// Add an invalid new category
Category newCategoryLongName = new Category()
{
CategoryName = "New Category Loooooooong Name",
};
context.Categories.Add(newCategoryLongName);
// The entire transaction will fail due to
// insertion failure for the second category
context.SaveChanges();
}
