عملگرهای مرتب سازی در Linq بخش دوم

در بخش قبل ، مثال اول را در این زمینه مشاهده کردیم . در این مقاله مثال دوم را بیان می کنیم :

مثال دوم :

در این مثال می خواهیم آرایه رشته ها را بر اساس طول هر یک از رشته ها مرتب کنیم :

                              
  var sortedWords =
  from word in words
  orderby word.Length
  word;

خروجی بصورت زیر است :

cherry , blueberry

 

نحوه نمایش آن نیز مانند مثال اول می باشد . کد مثال دوم بصورت زیر است :

                              
public static void OrderBy_Sample2()
{
    string[] words = { "cherry", "apple", "blueberry" };
    var sortedWords =
                    from word in words
                    orderby word.Length
                    select word;
    Console.WriteLine("The sorted list of words (by length):\n————————–");
    foreach (var word in sortedWords)
    {
        Console.WriteLine(word);
    }

برای رفتن سراغ مثال سوم ، نیاز به دو کلاس جدید بنام Product و ProductRepository می باشد . بنابراین ابتدا این دو کلاس را مطابق زیر ایجاد می کنیم و سپس در مقاله بعد مثال سوم را مطرح می کنیم .

تعریف کلاس Product :

کلاسی بنام Product به پروژه خود اضافه کنید و property های زیر را در آن تعریف کنید :

                              
public int ProductID { get; set; }
public string ProductName { get; set; }
public string Category { get; set; }
public decimal UnitPrice { get; set; }
int UnitsInStock { get; set; }

تعریف کلاس ProductRepository :

بدین منظور ، کلاسی بنام ProductRepository تعریف کنید و عبارت زیر را برای تعریف لیستی از محصولات در آن بنویسید :

private List<Product> _products;

سازنده این کلاس را بصورت زیر تعریف کنید :

                              
public ProductRepository()
{
    LoadProducts();
}

اکنون متد LoadProducts را بصورت زیر تعریف کنید (مقداردهی به کلاس Product) :

                              
private void LoadProducts()
{
    _products = new List
    {
        new Product { ProductID = 1, ProductName = "Chai", Category = "Beverages", UnitPrice = 18.0000M, UnitsInStock = 39 },
        new Product { ProductID = 2, ProductName = "Chang", Category = "Beverages", UnitPrice = 19.0000M, UnitsInStock = 17 },
        new Product { ProductID = 3, ProductName = "Aniseed Syrup", Category = "Condiments", UnitPrice = 10.0000M, UnitsInStock = 13 },
        new Product { ProductID = 4, ProductName = "Chef Anton's Cajun Seasoning", Category = "Condiments", UnitPrice = 22.0000M, UnitsInStock = 53 },
        new Product { ProductID = 5, ProductName = "Chef Anton's Gumbo Mix", Category = "Condiments", UnitPrice = 21.3500M, UnitsInStock = 0 },
        new Product { ProductID = 6, ProductName = "Grandma's Boysenberry Spread", Category = "Condiments", UnitPrice = 25.0000M, UnitsInStock = 120 },
        new Product { ProductID = 7, ProductName = "Uncle Bob's Organic Dried Pears", Category = "Produce", UnitPrice = 30.0000M, UnitsInStock = 15 },
        new Product { ProductID = 8, ProductName = "Northwoods Cranberry Sauce", Category = "Condiments", UnitPrice = 40.0000M, UnitsInStock = 6 },
        new Product { ProductID = 9, ProductName = "Mishi Kobe Niku", Category = "Meat/Poultry", UnitPrice = 97.0000M, UnitsInStock = 29 },
        new Product { ProductID = 10, ProductName = "Ikura", Category = "Seafood", UnitPrice = 31.0000M, UnitsInStock = 31 },
        new Product { ProductID = 11, ProductName = "Queso Cabrales", Category = "Dairy Products", UnitPrice = 21.0000M, UnitsInStock = 22 },
        new Product { ProductID = 12, ProductName = "Queso Manchego La Pastora", Category = "Dairy Products", UnitPrice = 38.0000M, UnitsInStock = 86 },
        new Product { ProductID = 13, ProductName = "Konbu", Category = "Seafood", UnitPrice = 6.0000M, UnitsInStock = 24 },
        new Product { ProductID = 14, ProductName = "Tofu", Category = "Produce", UnitPrice = 23.2500M, UnitsInStock = 35 },
        new Product { ProductID = 15, ProductName = "Genen Shouyu", Category = "Condiments", UnitPrice = 15.5000M, UnitsInStock = 39 },
        new Product { ProductID = 16, ProductName = "Pavlova", Category = "Confections", UnitPrice = 17.4500M, UnitsInStock = 29 },
        new Product { ProductID = 17, ProductName = "Alice Mutton", Category = "Meat/Poultry", UnitPrice = 39.0000M, UnitsInStock = 0 },
        new Product { ProductID = 18, ProductName = "Carnarvon Tigers", Category = "Seafood", UnitPrice = 62.5000M, UnitsInStock = 42 },
        new Product { ProductID = 19, ProductName = "Teatime Chocolate Biscuits", Category = "Confections", UnitPrice = 9.2000M, UnitsInStock = 25 },
        new Product { ProductID = 20, ProductName = "Sir Rodney's Marmalade", Category = "Confections", UnitPrice = 81.0000M, UnitsInStock = 40 },
        new Product { ProductID = 21, ProductName = "Sir Rodney's Scones", Category = "Confections", UnitPrice = 10.0000M, UnitsInStock = 3 },
        new Product { ProductID = 22, ProductName = "Gustaf's Knäckebröd", Category = "Grains/Cereals", UnitPrice = 21.0000M, UnitsInStock = 104 },
        new Product { ProductID = 23, ProductName = "Tunnbröd", Category = "Grains/Cereals", UnitPrice = 9.0000M, UnitsInStock = 61 },
        new Product { ProductID = 24, ProductName = "Guaraná Fantástica", Category = "Beverages", UnitPrice = 4.5000M, UnitsInStock = 20 },
        new Product { ProductID = 25, ProductName = "NuNuCa Nuß-Nougat-Creme", Category = "Confections", UnitPrice = 14.0000M, UnitsInStock = 76 },
        new Product { ProductID = 26, ProductName = "Gumbär Gummibärchen", Category = "Confections", UnitPrice = 31.2300M, UnitsInStock = 15 },
        new Product { ProductID = 27, ProductName = "Schoggi Schokolade", Category = "Confections", UnitPrice = 43.9000M, UnitsInStock = 49 },
        new Product { ProductID = 28, ProductName = "Rössle Sauerkraut", Category = "Produce", UnitPrice = 45.6000M, UnitsInStock = 26 },
        new Product { ProductID = 29, ProductName = "Thüringer Rostbratwurst", Category = "Meat/Poultry", UnitPrice = 123.7900M, UnitsInStock = 0 },
        new Product { ProductID = 30, ProductName = "Nord-Ost Matjeshering", Category = "Seafood", UnitPrice = 25.8900M, UnitsInStock = 10 },
        new Product { ProductID = 31, ProductName = "Gorgonzola Telino", Category = "Dairy Products", UnitPrice = 12.5000M, UnitsInStock = 0 },
        new Product { ProductID = 32, ProductName = "Mascarpone Fabioli", Category = "Dairy Products", UnitPrice = 32.0000M, UnitsInStock = 9 },
        new Product { ProductID = 33, ProductName = "Geitost", Category = "Dairy Products", UnitPrice = 2.5000M, UnitsInStock = 112 },
        new Product { ProductID = 34, ProductName = "Sasquatch Ale", Category = "Beverages", UnitPrice = 14.0000M, UnitsInStock = 111 },
        new Product { ProductID = 35, ProductName = "Steeleye Stout", Category = "Beverages", UnitPrice = 18.0000M, UnitsInStock = 20 },
        new Product { ProductID = 36, ProductName = "Inlagd Sill", Category = "Seafood", UnitPrice = 19.0000M, UnitsInStock = 112 },
        new Product { ProductID = 37, ProductName = "Gravad lax", Category = "Seafood", UnitPrice = 26.0000M, UnitsInStock = 11 },
        new Product { ProductID = 38, ProductName = "Côte de Blaye", Category = "Beverages", UnitPrice = 263.5000M, UnitsInStock = 17 },
        new Product { ProductID = 39, ProductName = "Chartreuse verte", Category = "Beverages", UnitPrice = 18.0000M, UnitsInStock = 69 },
        new Product { ProductID = 40, ProductName = "Boston Crab Meat", Category = "Seafood", UnitPrice = 18.4000M, UnitsInStock = 123 },
        new Product { ProductID = 41, ProductName = "Jack's New England Clam Chowder", Category = "Seafood", UnitPrice = 9.6500M, UnitsInStock = 85 },
        new Product { ProductID = 42, ProductName = "Singaporean Hokkien Fried Mee", Category = "Grains/Cereals", UnitPrice = 14.0000M, UnitsInStock = 26 },
        new Product { ProductID = 43, ProductName = "Ipoh Coffee", Category = "Beverages", UnitPrice = 46.0000M, UnitsInStock = 17 },
        new Product { ProductID = 44, ProductName = "Gula Malacca", Category = "Condiments", UnitPrice = 19.4500M, UnitsInStock = 27 },
        new Product { ProductID = 45, ProductName = "Rogede sild", Category = "Seafood", UnitPrice = 9.5000M, UnitsInStock = 5 },
        new Product { ProductID = 46, ProductName = "Spegesild", Category = "Seafood", UnitPrice = 12.0000M, UnitsInStock = 95 },
        new Product { ProductID = 47, ProductName = "Zaanse koeken", Category = "Confections", UnitPrice = 9.5000M, UnitsInStock = 36 },
        new Product { ProductID = 48, ProductName = "Chocolade", Category = "Confections", UnitPrice = 12.7500M, UnitsInStock = 15 },
        new Product { ProductID = 49, ProductName = "Maxilaku", Category = "Confections", UnitPrice = 20.0000M, UnitsInStock = 10 },
        new Product { ProductID = 50, ProductName = "Valkoinen suklaa", Category = "Confections", UnitPrice = 16.2500M, UnitsInStock = 65 },
        new Product { ProductID = 51, ProductName = "Manjimup Dried Apples", Category = "Produce", UnitPrice = 53.0000M, UnitsInStock = 20 },
        new Product { ProductID = 52, ProductName = "Filo Mix", Category = "Grains/Cereals", UnitPrice = 7.0000M, UnitsInStock = 38 },
        new Product { ProductID = 53, ProductName = "Perth Pasties", Category = "Meat/Poultry", UnitPrice = 32.8000M, UnitsInStock = 0 },
        new Product { ProductID = 54, ProductName = "Tourtière", Category = "Meat/Poultry", UnitPrice = 7.4500M, UnitsInStock = 21 },
        new Product { ProductID = 55, ProductName = "Pâté chinois", Category = "Meat/Poultry", UnitPrice = 24.0000M, UnitsInStock = 115 },
        new Product { ProductID = 56, ProductName = "Gnocchi di nonna Alice", Category = "Grains/Cereals", UnitPrice = 38.0000M, UnitsInStock = 21 }                
    };
}

و در نهایت ، متدی برای برگرداندن تمامی محصولات تعریف کنید :

public IEnumerable<Product> GetAll()

        {

            return _products;

        }

بنابراین بطور کلی کلاس ProductRepository دارای یک سازنده ، یک property و دو متد می باشد .

حال به مثال سوم از مبحث مرتب سازی (sorting) در Linq در مقاله بعد توجه کنید …


تاریخ انتشار : ۲۵ اسفند ۱۳۹۴



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