static void PLinqExceptions(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var parallel = storage.Products.AsParallel().Select(p =>
{
if (p.ProductName.StartsWith("P"))
{
throw new Exception("Problem with product: " + p.ProductName);
}
return(new { p.ProductId, p.ProductName, Thread.CurrentThread.ManagedThreadId });
});
try
{
foreach (var p in parallel)
{
Console.WriteLine("Id = {0}, Product = {1}, ThreadId = {2}", p.ProductId, p.ProductName, p.ManagedThreadId);
}
}
catch (AggregateException aggrex)
{
aggrex.Handle(ex =>
{
Console.WriteLine(ex.Message);
return(true);
});
}
}
static void LinqFirstOrDefaultCondition(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var product789 = storage.Products.FirstOrDefault(p => p.ProductId == 789);
Console.WriteLine("Product 789 exists: {0}", product789 != null);
}
static void LinqLastSimple(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var product12 = (
from p in storage.Products
where p.ProductId == 12
select p).Last();
ObjectDumper.Write(product12);
}
static void LinqMaxElements(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var categories =
from p in storage.Products
group p by p.Category into g
let maxPrice = g.Max(p => p.UnitPrice)
select new { Category = g.Key, MostExpensiveProducts = g.Where(p => p.UnitPrice == maxPrice) };
ObjectDumper.Write(categories, 1);
}
static void LinqCountNested(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var orderCounts =
from c in storage.Customers
select new { c.CustomerId, OrderCount = c.Orders.Count() };
// Fluent expression equivalent.
// var orderCounts = storage.Customers.Select(c => new { c.CustomerId, OrderCount = c.Orders.Count() });
ObjectDumper.Write(orderCounts);
}
static void PLinqWithDegreeOfParallelism(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var parallel =
from p in storage.Products.AsParallel().WithDegreeOfParallelism(Environment.ProcessorCount)
select new { p.ProductId, p.ProductName, Thread.CurrentThread.ManagedThreadId };
foreach (var p in parallel)
{
Console.WriteLine("Id = {0}, Product = {1}, ThreadId = {2}", p.ProductId, p.ProductName, p.ManagedThreadId);
}
}
static void PLinqAsUnordered(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var parallel =
from p in storage.Products.AsParallel().AsOrdered().Take(10).AsUnordered()
select new { p.ProductId, p.ProductName, Thread.CurrentThread.ManagedThreadId };
foreach (var p in parallel)
{
Console.WriteLine("Id = {0}, Product = {1}, ThreadId = {2}", p.ProductId, p.ProductName, p.ManagedThreadId);
}
}
static void PLinqWithExecutionMode(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var parallel =
from p in storage.Products.AsParallel().WithExecutionMode(ParallelExecutionMode.ForceParallelism)
select new { p.ProductId, p.ProductName, Thread.CurrentThread.ManagedThreadId };
foreach (var p in parallel)
{
Console.WriteLine("Id = {0}, Product = {1}, ThreadId = {2}", p.ProductId, p.ProductName, p.ManagedThreadId);
}
}
static void LinqCountGrouped(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var categoryCounts =
from p in storage.Products
group p by p.Category into g
select new { Category = g.Key, ProductCount = g.Count() };
// Fluent expression equivalent.
// var categoryCounts = storage.Products.GroupBy(p => p.Category, (k, g) => new { Category = k, ProductCount = g.Count() });
ObjectDumper.Write(categoryCounts);
}
static void LinqGroupBySimple3(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var orderGroups =
from p in storage.Products
group p by p.Category into g
select new { Category = g.Key, Products = g };
// Fluent expression equivalent.
// var orderGroups = storage.Products.GroupBy(p => p.Category, (k, g) => new { Category = k, Products = g });
ObjectDumper.Write(orderGroups, 1);
}
static void LinqThenByDescendingSimple(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var sortedProducts =
from prod in storage.Products
orderby prod.Category, prod.UnitPrice descending
select prod;
// Fluent expression equivalent.
// var sortedProducts = storage.Products.OrderBy(prod => prod.Category).ThenByDescending(prod => prod.UnitPrice);
ObjectDumper.Write(sortedProducts);
}
static void LinqOrderBySimple3(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var sortedProducts =
from prod in storage.Products
orderby prod.ProductName
select prod;
// Fluent expression equivalent.
// var sortedProducts = storage.Products.OrderBy(prod => prod.ProductName);
ObjectDumper.Write(sortedProducts);
}
static void LinqMaxGrouped(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var categories =
from p in storage.Products
group p by p.Category into g
select new { Category = g.Key, MostExpensivePrice = g.Max(p => p.UnitPrice) };
// Fluent expression equivalent.
// var categories = storage.Products.GroupBy(p => p.Category, (k, g) => new { Category = k, MostExpensivePrice = g.Max(p => p.UnitPrice) });
ObjectDumper.Write(categories);
}
static void LinqSumGrouped(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var categories =
from p in storage.Products
group p by p.Category into g
select new { Category = g.Key, TotalUnitsInStock = g.Sum(p => p.UnitsInStock) };
// Fluent expression equivalent.
// var categories = storage.Products.GroupBy(p => p.Category, (k, g) => new { Category = k, TotalUnitsInStock = g.Sum(p => p.UnitsInStock) });
ObjectDumper.Write(categories);
}
static void LinqDistinct2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var categoryNames = (
from p in storage.Products
select p.Category)
.Distinct();
Console.WriteLine("Category names:");
foreach (var n in categoryNames)
{
Console.WriteLine(n);
}
}
static void LinqAllGrouped(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var productGroups =
from p in storage.Products
group p by p.Category into g
where g.All(p => p.UnitsInStock > 0)
select new { Category = g.Key, Products = g };
// Fluent expression equivalent.
// var productGroups = storage.Products.GroupBy(p => p.Category, (k, g) => new { Category = k, Products = g }).Where(g => g.Products.All(p => p.UnitsInStock > 0));
ObjectDumper.Write(productGroups, 1);
}
static void LinqSelectManyIndexed(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
// Fluent expression only.
var customerOrders = storage.Customers.SelectMany((c, cIndex) => c.Orders.Select(o => "Customer #" + (cIndex + 1) + " has an order with OrderID " + o.OrderId));
/*
* var customerOrders = storage.Customers.SelectMany(
* (c, cIndex) => c.Orders.Select(o => new { index = cIndex, order = o }),
* (c, o) => "Customer #" + (o.index + 1) + " has an order with OrderID " + o.order.OrderId);
*/
ObjectDumper.Write(customerOrders);
}
static void LinqTakeNested(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var first3WaOrders = (
from c in storage.Customers
from o in c.Orders
where c.Region == "WA"
select new { c.CustomerId, o.OrderId, o.OrderDate }).Take(3);
Console.WriteLine("First 3 orders in WA:");
foreach (var order in first3WaOrders)
{
ObjectDumper.Write(order);
}
}
static void LinqSelectAnonymousTypes3(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var productInfos =
from p in storage.Products
select new { p.ProductName, p.Category, Price = p.UnitPrice };
// Fluent expression equivalent.
// var productInfos = storage.Products.Select(p => new { p.ProductName, p.Category, Price = p.UnitPrice });
Console.WriteLine("Product Info:");
foreach (var productInfo in productInfos)
{
Console.WriteLine("{0} is in the category {1} and costs {2} per unit.", productInfo.ProductName, productInfo.Category, productInfo.Price);
}
}
static void LinqGroupByNested(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var customerOrderGroups =
from c in storage.Customers
select
new
{
c.CompanyName,
YearGroups =
from o in c.Orders
group o by o.OrderDate.Year into yg
select
new
{
Year = yg.Key,
MonthGroups =
from o in yg
group o by o.OrderDate.Month into mg
select new { Month = mg.Key, Orders = mg }
}
};
// Fluent expression equivalent.
/*
* var customerOrderGroups = storage.Customers.Select(c =>
* new
* {
* c.CompanyName,
* YearGroups = c.Orders.GroupBy(
* yo => yo.OrderDate.Year,
* (yk, yg) =>
* new
* {
* Year = yk,
* MonthGroups = yg.GroupBy(
* mo => mo.OrderDate.Month,
* (mk, mg) => new { Month = mk, Orders = mg })
* })
* });
*/
ObjectDumper.Write(customerOrderGroups, 3);
}
static void LinqSelectSimple2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var productNames =
from p in storage.Products
select p.ProductName;
// Fluent expression equivalent.
// var productNames = storage.Products.Select(p => p.ProductName);
Console.WriteLine("Product Names:");
foreach (var productName in productNames)
{
Console.WriteLine(productName);
}
}
static void LinqSkipNested(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var waOrders =
from cust in storage.Customers
from order in cust.Orders
where cust.Region == "WA"
select new { cust.CustomerId, order.OrderId, order.OrderDate };
var allButFirst2Orders = waOrders.Skip(2);
Console.WriteLine("All but first 2 orders in WA:");
foreach (var order in allButFirst2Orders)
{
ObjectDumper.Write(order);
}
}
static void LinqWhereSimple2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var soldOutProducts =
from prod in storage.Products
where (prod.UnitsInStock == 0)
select prod;
// Fluent expression equivalent.
// var soldOutProducts = storage.Products.Where(prod => prod.UnitsInStock == 0);
Console.WriteLine("Sold out products:");
foreach (var product in soldOutProducts)
{
Console.WriteLine("{0} is sold out!", product.ProductName);
}
}
static void LinqWhereSimple3(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var expensiveInStockProducts =
from prod in storage.Products
where ((prod.UnitsInStock > 0) && (prod.UnitPrice > 3.00M))
select prod;
// Fluent expression equivalent.
// var expensiveInStockProducts = storage.Products.Where(prod => (prod.UnitsInStock > 0) && (prod.UnitPrice > 3.00M));
Console.WriteLine("In-stock products that cost more than 3.00:");
foreach (var product in expensiveInStockProducts)
{
Console.WriteLine("{0} is in stock and costs more than 3.00.", product.ProductName);
}
}
static void LinqUnion2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var productFirstChars =
from p in storage.Products
select p.ProductName[0];
var customerFirstChars =
from c in storage.Customers
select c.CompanyName[0];
var uniqueFirstChars = productFirstChars.Union(customerFirstChars);
Console.WriteLine("Unique first letters from Product names and Customer names:");
foreach (var ch in uniqueFirstChars)
{
Console.WriteLine(ch);
}
}
static void LinqConcat2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var customerNames =
from c in storage.Customers
select c.CompanyName;
var productNames =
from p in storage.Products
select p.ProductName;
var allNames = customerNames.Concat(productNames);
Console.WriteLine("Customer and product names:");
foreach (var n in allNames)
{
Console.WriteLine(n);
}
}
static void LinqExcept2(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var productFirstChars =
from p in storage.Products
select p.ProductName[0];
var customerFirstChars =
from c in storage.Customers
select c.CompanyName[0];
var productOnlyFirstChars = productFirstChars.Except(customerFirstChars);
Console.WriteLine("First letters from Product names, but not from Customer names:");
foreach (var ch in productOnlyFirstChars)
{
Console.WriteLine(ch);
}
}
static void LinqSelectManyCompoundFrom3(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var orders =
from c in storage.Customers
from o in c.Orders
where o.OrderDate >= new DateTime(1998, 1, 1)
select new { c.CustomerId, o.OrderId, o.OrderDate };
// Fluent expression equivalents.
// var orders = storage.Customers.SelectMany(c => c.Orders.Where(o => o.OrderDate >= new DateTime(1998, 1, 1)).Select(o => new { c.CustomerId, o.OrderId, o.OrderDate }));
/*
* var orders = storage.Customers.SelectMany(
* c => c.Orders.Where(o => o.OrderDate >= new DateTime(1998, 1, 1)),
* (c, o) => new {c.CustomerId, o.OrderId, o.OrderDate});
*/
ObjectDumper.Write(orders);
}
static void LinqWhereDrilldown(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var waCustomers =
from cust in storage.Customers
where (cust.Region == "WA")
select cust;
// Fluent expression equivalent.
// var waCustomers = storage.Customers.Where(cust => cust.Region == "WA");
Console.WriteLine("Customers from Washington and their orders:");
foreach (var customer in waCustomers)
{
Console.WriteLine("Customer {0}: {1}", customer.CustomerId, customer.CompanyName);
foreach (var order in customer.Orders)
{
Console.WriteLine(" Order {0}: {1}", order.OrderId, order.OrderDate);
}
}
}
static void LinqSelectManyFromAssignment(CustomersStorage storage)
{
Console.WriteLine("=== " + MethodInfo.GetCurrentMethod().Name + " ===");
var orders =
from c in storage.Customers
from o in c.Orders
let total = o.Total
where total >= 2000.0M
select new { c.CustomerId, o.OrderId, total };
// Fluent expression equivalents.
// var orders = storage.Customers.SelectMany(c => c.Orders.Select(o => new { order = o, total = o.Total }).Where(o => o.total < 500.00M).Select(o => new { c.CustomerId, o.order.OrderId, o.total }));
/*
* var orders = storage.Customers.SelectMany(
* c => c.Orders.Select(o => new { order = o, total = o.Total }).Where(o => o.total < 500.00M),
* (c, o) => new { c.CustomerId, o.order.OrderId, o.total });
*/
ObjectDumper.Write(orders);
}
