public virtual async Task<Maybe<TModel>> GetByIdAsync(long id)
{
    Guard.ArgumentInRange(id, 1, long.MaxValue, nameof(id));

    var entity = await UnTrackedEntitySet.Where(a => a.Id == id)
        .ProjectTo<TModel>(_mapper.ConfigurationProvider).SingleOrDefaultAsync();

    return entity;
}

Maybe<T> = Nullable<T>

using System;

namespace Pivot.Sample1
{
    public class Expense
    {
        public DateTime Date { set; get; }
        public string Department { set; get; }
        public decimal Expenses { set; get; }
    }
}

using System;
using System.Collections.Generic;

namespace Pivot.Sample1
{
    public class ExpenseDataSource
    {
        public static IList<Expense> ExpensesDataSource()
        {
            return new List<Expense>
            {
                new Expense { Date = new DateTime(2011,11,1), Department = "Computer", Expenses = 100 },
                new Expense { Date = new DateTime(2011,11,1), Department = "Math", Expenses = 200 },
                new Expense { Date = new DateTime(2011,11,1), Department = "Physics", Expenses = 150 },

                new Expense { Date = new DateTime(2011,10,1), Department = "Computer", Expenses = 75 },
                new Expense { Date = new DateTime(2011,10,1), Department = "Math", Expenses = 150 },
                new Expense { Date = new DateTime(2011,10,1), Department = "Physics", Expenses = 130 },

                new Expense { Date = new DateTime(2011,9,1), Department = "Computer", Expenses = 90 },
                new Expense { Date = new DateTime(2011,9,1), Department = "Math", Expenses = 95 },
                new Expense { Date = new DateTime(2011,9,1), Department = "Physics", Expenses = 100 }
            };
        }
    }
}

using System.Collections;
using System.Linq;

namespace Pivot.Sample1
{
    public class PivotTable
    {
        public static IList ExpensesCrossTab()
        {
            return ExpenseDataSource
                        .ExpensesDataSource()
                        .GroupBy(t =>
                                   new
                                   {
                                       Year = t.Date.Year,
                                       Month = t.Date.Month
                                   })
                        .Select(myGroup =>
                                   new
                                   {
                                       //Year = myGroup.Key.Year,
                                       Month = myGroup.Key.Month,
                                       ComputerDepartment = myGroup.Where(x => x.Department == "Computer").Sum(x => x.Expenses),
                                       MathDepartment = myGroup.Where(x => x.Department == "Math").Sum(x => x.Expenses),
                                       PhysicsDepartment = myGroup.Where(x => x.Department == "Physics").Sum(x => x.Expenses)
                                   })
                        .ToList();
        }
    }
}

using System;

namespace Pivot.Sample2
{
    public class StudentStat
    {
        public int Id { set; get; }
        public string Name { set; get; }
        public DateTime Date { set; get; }
        public bool IsPresent { set; get; }
    }
}

using System;
using System.Collections.Generic;

namespace Pivot.Sample2
{
    public class StudentsStatDataSource
    {
        public static IList<StudentStat> CreateMonthlyReportDataSource()
        {
            var result = new List<StudentStat>();
            var rnd = new Random();

            for (int day = 1; day < 6; day++)
            {
                for (int student = 1; student < 6; student++)
                {
                    result.Add(new StudentStat
                    {
                        Id = student,
                        Date = new DateTime(2011, 11, day),
                        IsPresent = rnd.Next(-1, 1) == 0 ? true : false,
                        Name = "student " + student
                    });
                }
            }

            return result;
        }
    }
}

using System.Collections;
using System.Linq;

namespace Pivot.Sample2
{
    public class PivotTable
    {
        public static IList StudentsStatCrossTab()
        {
            return StudentsStatDataSource
                        .CreateWeeklyReportDataSource()
                        .GroupBy(x =>
                                  new
                                  {
                                      x.Id
                                  })
                        .Select(myGroup =>
                                  new
                                  {
                                      myGroup.Key.Id,
                                      Name = myGroup.First().Name,
                                      Day1IsPresent = myGroup.Where(x => x.Date.Day == 1).First().IsPresent,
                                      Day2IsPresent = myGroup.Where(x => x.Date.Day == 2).First().IsPresent,
                                      Day3IsPresent = myGroup.Where(x => x.Date.Day == 3).First().IsPresent,
                                      Day4IsPresent = myGroup.Where(x => x.Date.Day == 4).First().IsPresent,
                                      Day5IsPresent = myGroup.Where(x => x.Date.Day == 5).First().IsPresent,
                                      PresentsCount = myGroup.Where(x => x.IsPresent).Count(),
                                      AbsentsCount = myGroup.Where(x => !x.IsPresent).Count()
                                  })
                        .ToList();
        }
    }
}

<httpRuntime executionTimeout="1200" maxRequestLength="39936" />

using System;
using System.Configuration;
using System.Web.Configuration;

/// <summary>
/// کلاسی جهت نمایش اندازه مجاز فایل قابل ارسال به سرور
/// </summary>
public class CMaxLimit
{
  /// <summary>
  /// اندازه مجاز فایل قابل ارسال به سرور
  /// </summary>
  /// <returns></returns>
  public static string MaxFileUploadSizeLimit()
  {
      //مقدار پیش فرض
      int resultKB = 4096;

      //machine.config
      Configuration mConfig =
          WebConfigurationManager.OpenMachineConfiguration();
      bool mConfigIsLocked = false;
      HttpRuntimeSection section =
          mConfig.GetSection("system.web/httpRuntime") as HttpRuntimeSection;
      if (section != null)
      {
          resultKB = section.MaxRequestLength;
          mConfigIsLocked = section.ElementInformation.IsLocked;
      }

      //web.config
      if (!mConfigIsLocked)
      {
          HttpRuntimeSection httpRuntimeSection =
              WebConfigurationManager.GetSection("system.web/httpRuntime") as HttpRuntimeSection;
          if (httpRuntimeSection != null)
          {
              resultKB = httpRuntimeSection.MaxRequestLength;
          }
      }

      return
           SizeToString(resultKB * 1024);
  }

  /// <summary>
  /// نمایش اندازه یک فایل به صورتی قابل درک
  /// </summary>
  /// <param name="len">اندازه فایل</param>
  /// <returns></returns>
  public static string SizeToString(long len)
  {
      int order = 0;
      string[] sizes = new[] { "B", "KB", "MB", "GB" };
      while (len >= 1024 && order + 1 < sizes.Length)
      {
          order++;
          len = len / 1024;
      }
      return String.Format("{0:0.##} {1}", len, sizes[order]);
  }
}

namespace NHSample1.Domain
{
   public class Product
   {
       public int Id { get; set; }
       public string Name { get; set; }
       public decimal UnitPrice { get; set; }
       public bool Discontinued { get; set; }
   }
}

using FluentNHibernate.Mapping;
using NHSample1.Domain;

namespace NHSample1.Mappings
{
   public class ProductMapping : ClassMap<Product>
   {
       public ProductMapping()
       {
           Not.LazyLoad();
           Id(p => p.Id).GeneratedBy.HiLo("1000");
           Map(p => p.Name).Length(50).Not.Nullable();
           Map(p => p.UnitPrice).Not.Nullable();
           Map(p => p.Discontinued).Not.Nullable();
       }
   }
}

using NUnit.Framework;
using FluentNHibernate.Testing;
using NHSample1.Domain;

namespace UnitTests
{
   [TestFixture]
   public class ProductMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_product()
       {
           new PersistenceSpecification<Product>(Session)
                   .CheckProperty(p => p.Id, 1001)
                   .CheckProperty(p => p.Name, "Apples")
                   .CheckProperty(p => p.UnitPrice, 10.45m)
                   .CheckProperty(p => p.Discontinued, true)
                   .VerifyTheMappings();
       }
   }
}

ProductMapping_Fixture.can_correctly_map_product : Passed
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 10.45, @p2 = True, @p3 = 1001
NHibernate: SELECT product0_.Id as Id1_0_, product0_.Name as Name1_0_, product0_.UnitPrice as UnitPrice1_0_, product0_.Discontinued as Disconti4_1_0_ FROM "Product" product0_ WHERE product0_.Id=@p0;@p0 = 1001

using System;
namespace NHSample1.Domain
{
   public class Employee
   {
       public int Id { set; get; }
       public string LastName { get; set; }
       public string FirstName { get; set; }
   }
}

using NHSample1.Domain;
using FluentNHibernate.Mapping;

namespace NHSample1.Mappings
{
   public class EmployeeMapping : ClassMap<Employee>
   {
       public EmployeeMapping()
       {
           Not.LazyLoad();
           Id(e => e.Id).GeneratedBy.Assigned();
           Map(e => e.LastName).Length(50);
           Map(e => e.FirstName).Length(50);
       }
   }
}

using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class EmployeeMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_employee()
       {
           new PersistenceSpecification<Employee>(Session)
                   .CheckProperty(p => p.Id, 1001)
                   .CheckProperty(p => p.FirstName, "name1")
                   .CheckProperty(p => p.LastName, "lname1")
                   .VerifyTheMappings();
       }
   }
}

NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Employee" (LastName, FirstName, Id) VALUES (@p0, @p1, @p2);@p0 = 'lname1', @p1 = 'name1', @p2 = 1001
NHibernate: SELECT employee0_.Id as Id4_0_, employee0_.LastName as LastName4_0_, employee0_.FirstName as FirstName4_0_ FROM "Employee" employee0_ WHERE employee0_.Id=@p0;@p0 = 1001

namespace NHSample1.Domain
{
   public class OrderItem
   {
       public int Id { get; set; }
       public int Quantity { get; set; }
       public Product Product { get; set; }
   }
}

using FluentNHibernate.Mapping;
using NHSample1.Domain;

namespace NHSample1.Mappings
{
   public class OrderItemMapping : ClassMap<OrderItem>
   {
       public OrderItemMapping()
       {
           Not.LazyLoad();
           Id(oi => oi.Id).GeneratedBy.Assigned();
           Map(oi => oi.Quantity).Not.Nullable();
           References(oi => oi.Product).Not.Nullable();
       }
   }
}

using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class OrderItemMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_order_item()
       {
           var product = new Product
           {
               Name = "Apples",
               UnitPrice = 4.5m,
               Discontinued = true
           };

           new PersistenceSpecification<OrderItem>(Session)
                       .CheckProperty(p => p.Id, 1)
                       .CheckProperty(p => p.Quantity, 5)
                       .CheckReference(p => p.Product, product)
                       .VerifyTheMappings();
       }
   }
}

using System.Collections;
using NHSample1.Domain;

namespace UnitTests
{
   public class CustomEqualityComparer : IEqualityComparer
   {
       public bool Equals(object x, object y)
       {
           if (ReferenceEquals(x, y)) return true;
           if (x == null || y == null) return false;

           if (x is Product && y is Product)
               return (x as Product).Id == (y as Product).Id;

           if (x is Customer && y is Customer)
               return (x as Customer).Id == (y as Customer).Id;

           if (x is Employee && y is Employee)
               return (x as Employee).Id == (y as Employee).Id;

           if (x is OrderItem && y is OrderItem)
               return (x as OrderItem).Id == (y as OrderItem).Id;
          

           return x.Equals(y);
       }

       public int GetHashCode(object obj)
       {
           //شاید وقتی دیگر
           return obj.GetHashCode();
       }
   }
}

new PersistenceSpecification<OrderItem>(Session, new CustomEqualityComparer())

NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 4.5, @p2 = True, @p3 = 1001
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 5, @p1 = 1001, @p2 = 1
NHibernate: SELECT orderitem0_.Id as Id0_1_, orderitem0_.Quantity as Quantity0_1_, orderitem0_.Product_id as Product3_0_1_, product1_.Id as Id3_0_, product1_.Name as Name3_0_, product1_.UnitPrice as UnitPrice3_0_, product1_.Discontinued as Disconti4_3_0_ FROM "OrderItem" orderitem0_ inner join "Product" product1_ on orderitem0_.Product_id=product1_.Id WHERE orderitem0_.Id=@p0;@p0 = 1

using System;
using System.Collections.Generic;

namespace NHSample1.Domain
{
   public class Order
   {
       public int Id { set; get; }
       public DateTime OrderDate { get; set; }
       public Employee Employee { get; set; }
       public Customer Customer { get; set; }
       public IList<OrderItem> OrderItems { get; set; }
   }
}

using NHSample1.Domain;
using FluentNHibernate.Mapping;

namespace NHSample1.Mappings
{
   public class OrderMapping : ClassMap<Order>
   {
       public OrderMapping()
       {
           Not.LazyLoad();
           Id(o => o.Id).GeneratedBy.GuidComb();
           Map(o => o.OrderDate).Not.Nullable();
           References(o => o.Employee).Not.Nullable();
           References(o => o.Customer).Not.Nullable();
           HasMany(o => o.OrderItems)
               .AsList(index => index.Column("ListIndex").Type<int>());
       }
   }
}

using System;
using System.Collections.Generic;
using NUnit.Framework;
using NHSample1.Domain;
using FluentNHibernate.Testing;

namespace UnitTests
{
   [TestFixture]
   public class OrderMapping_Fixture : FixtureBase
   {
       [Test]
       public void can_correctly_map_an_order()
       {
           {
               var product1 =
                   new Product
                   {
                       Name = "Apples",
                       UnitPrice = 4.5m,
                       Discontinued = true
                   };
               var product2 =
                   new Product
                   {
                       Name = "Pears",
                       UnitPrice = 3.5m,
                       Discontinued = false
                   };

               Session.Save(product1);
               Session.Save(product2);

               var items = new List<OrderItem>
                               {
                                   new OrderItem
                                   {
                                       Id = 1,
                                       Quantity = 100,
                                       Product = product1
                                   },
                                   new OrderItem
                                   {
                                       Id = 2,
                                       Quantity = 200,
                                       Product = product2
                                   }
                               };

               var customer = new Customer
               {
                   FirstName = "Vahid",
                   LastName = "Nasiri",
                   AddressLine1 = "Addr1",
                   AddressLine2 = "Addr2",
                   PostalCode = "1234",
                   City = "Tehran",
                   CountryCode = "IR"
               };

               var employee =
                   new Employee
                   {
                       FirstName = "name1",
                       LastName = "lname1"
                   };


              
               var order = new Order
               {
                   Customer = customer,
                   Employee = employee,
                   OrderDate = DateTime.Today,
                   OrderItems = items
               };

               new PersistenceSpecification<Order>(Session, new CustomEqualityComparer())
                   .CheckProperty(o => o.OrderDate, order.OrderDate)
                   .CheckReference(o => o.Customer, order.Customer)
                   .CheckReference(o => o.Employee, order.Employee)
                   .CheckList(o => o.OrderItems, order.OrderItems)
                   .VerifyTheMappings();
           }
       }
   }
}

OrderMapping_Fixture.can_correctly_map_an_order : Passed
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 2, @p1 = 1
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 3, @p1 = 2
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Apples', @p1 = 4.5, @p2 = True, @p3 = 1001
NHibernate: INSERT INTO "Product" (Name, UnitPrice, Discontinued, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 'Pears', @p1 = 3.5, @p2 = False, @p3 = 1002
NHibernate: INSERT INTO "Customer" (FirstName, LastName, AddressLine1, AddressLine2, PostalCode, City, CountryCode, Id) VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7);@p0 = 'Vahid', @p1 = 'Nasiri', @p2 = 'Addr1', @p3 = 'Addr2', @p4 = '1234', @p5 = 'Tehran', @p6 = 'IR', @p7 = 2002
NHibernate: select next_hi from hibernate_unique_key
NHibernate: update hibernate_unique_key set next_hi = @p0 where next_hi = @p1;@p0 = 4, @p1 = 3
NHibernate: INSERT INTO "Employee" (LastName, FirstName, Id) VALUES (@p0, @p1, @p2);@p0 = 'lname1', @p1 = 'name1', @p2 = 3003
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 100, @p1 = 1001, @p2 = 1
NHibernate: INSERT INTO "OrderItem" (Quantity, Product_id, Id) VALUES (@p0, @p1, @p2);@p0 = 200, @p1 = 1002, @p2 = 2
NHibernate: INSERT INTO "Order" (OrderDate, Employee_id, Customer_id, Id) VALUES (@p0, @p1, @p2, @p3);@p0 = 2009/10/10 12:00:00 ق.ظ, @p1 = 3003, @p2 = 2002, @p3 = 0
NHibernate: UPDATE "OrderItem" SET Order_id = @p0, ListIndex = @p1 WHERE Id = @p2;@p0 = 0, @p1 = 0, @p2 = 1
NHibernate: UPDATE "OrderItem" SET Order_id = @p0, ListIndex = @p1 WHERE Id = @p2;@p0 = 0, @p1 = 1, @p2 = 2
NHibernate: SELECT order0_.Id as Id1_2_, order0_.OrderDate as OrderDate1_2_, order0_.Employee_id as Employee3_1_2_, order0_.Customer_id as Customer4_1_2_, employee1_.Id as Id4_0_, employee1_.LastName as LastName4_0_, employee1_.FirstName as FirstName4_0_, customer2_.Id as Id2_1_, customer2_.FirstName as FirstName2_1_, customer2_.LastName as LastName2_1_, customer2_.AddressLine1 as AddressL4_2_1_, customer2_.AddressLine2 as AddressL5_2_1_, customer2_.PostalCode as PostalCode2_1_, customer2_.City as City2_1_, customer2_.CountryCode as CountryC8_2_1_ FROM "Order" order0_ inner join "Employee" employee1_ on order0_.Employee_id=employee1_.Id inner join "Customer" customer2_ on order0_.Customer_id=customer2_.Id WHERE order0_.Id=@p0;@p0 = 0
NHibernate: SELECT orderitems0_.Order_id as Order4_2_, orderitems0_.Id as Id2_, orderitems0_.ListIndex as ListIndex2_, orderitems0_.Id as Id0_1_, orderitems0_.Quantity as Quantity0_1_, orderitems0_.Product_id as Product3_0_1_, product1_.Id as Id3_0_, product1_.Name as Name3_0_, product1_.UnitPrice as UnitPrice3_0_, product1_.Discontinued as Disconti4_3_0_ FROM "OrderItem" orderitems0_ inner join "Product" product1_ on orderitems0_.Product_id=product1_.Id WHERE orderitems0_.Order_id=@p0;@p0 = 0

SessionSource.BuildSchema(Session, true);

    drop table if exists "OrderItem"

    drop table if exists "Order"

    drop table if exists "Customer"

    drop table if exists "Product"

    drop table if exists "Employee"

    drop table if exists hibernate_unique_key

    create table "OrderItem" (
        Id INTEGER not null,
       Quantity INTEGER not null,
       Product_id INTEGER not null,
       Order_id INTEGER,
       ListIndex INTEGER,
       primary key (Id)
    )

    create table "Order" (
        Id INTEGER not null,
       OrderDate DATETIME not null,
       Employee_id INTEGER not null,
       Customer_id INTEGER not null,
       primary key (Id)
    )

    create table "Customer" (
        Id INTEGER not null,
       FirstName TEXT not null,
       LastName TEXT not null,
       AddressLine1 TEXT not null,
       AddressLine2 TEXT,
       PostalCode TEXT not null,
       City TEXT not null,
       CountryCode TEXT not null,
       primary key (Id)
    )

    create table "Product" (
        Id INTEGER not null,
       Name TEXT not null,
       UnitPrice NUMERIC not null,
       Discontinued INTEGER not null,
       primary key (Id)
    )

    create table "Employee" (
        Id INTEGER not null,
       LastName TEXT,
       FirstName TEXT,
       primary key (Id)
    )

    create table hibernate_unique_key (
         next_hi INTEGER
    )

           var cfg = Fluently.Configure().Database(
              // SQLiteConfiguration.Standard.ShowSql().InMemory
              MsSqlConfiguration
              .MsSql2008
              .ShowSql()
              .ConnectionString("Data Source=(local);Initial Catalog=testdb2009;Integrated Security = true")
               );

    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3EF88858466CFBF7]') AND parent_object_id = OBJECT_ID('[OrderItem]'))
alter table [OrderItem]  drop constraint FK3EF88858466CFBF7


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3EF888589F32DE52]') AND parent_object_id = OBJECT_ID('[OrderItem]'))
alter table [OrderItem]  drop constraint FK3EF888589F32DE52


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3117099B1EBA72BC]') AND parent_object_id = OBJECT_ID('[Order]'))
alter table [Order]  drop constraint FK3117099B1EBA72BC


    if exists (select 1 from sys.objects where object_id = OBJECT_ID(N'[FK3117099BB2F9593A]') AND parent_object_id = OBJECT_ID('[Order]'))
alter table [Order]  drop constraint FK3117099BB2F9593A


    if exists (select * from dbo.sysobjects where id = object_id(N'[OrderItem]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [OrderItem]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Order]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Order]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Customer]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Customer]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Product]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Product]

    if exists (select * from dbo.sysobjects where id = object_id(N'[Employee]') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table [Employee]

    if exists (select * from dbo.sysobjects where id = object_id(N'hibernate_unique_key') and OBJECTPROPERTY(id, N'IsUserTable') = 1) drop table hibernate_unique_key

    create table [OrderItem] (
        Id INT not null,
       Quantity INT not null,
       Product_id INT not null,
       Order_id INT null,
       ListIndex INT null,
       primary key (Id)
    )

    create table [Order] (
        Id INT not null,
       OrderDate DATETIME not null,
       Employee_id INT not null,
       Customer_id INT not null,
       primary key (Id)
    )

    create table [Customer] (
        Id INT not null,
       FirstName NVARCHAR(50) not null,
       LastName NVARCHAR(50) not null,
       AddressLine1 NVARCHAR(50) not null,
       AddressLine2 NVARCHAR(50) null,
       PostalCode NVARCHAR(10) not null,
       City NVARCHAR(50) not null,
       CountryCode NVARCHAR(2) not null,
       primary key (Id)
    )

    create table [Product] (
        Id INT not null,
       Name NVARCHAR(50) not null,
       UnitPrice DECIMAL(19,5) not null,
       Discontinued BIT not null,
       primary key (Id)
    )

    create table [Employee] (
        Id INT not null,
       LastName NVARCHAR(50) null,
       FirstName NVARCHAR(50) null,
       primary key (Id)
    )

    alter table [OrderItem]
        add constraint FK3EF88858466CFBF7
        foreign key (Product_id)
        references [Product]

    alter table [OrderItem]
        add constraint FK3EF888589F32DE52
        foreign key (Order_id)
        references [Order]

    alter table [Order]
        add constraint FK3117099B1EBA72BC
        foreign key (Employee_id)
        references [Employee]

    alter table [Order]
        add constraint FK3117099BB2F9593A
        foreign key (Customer_id)
        references [Customer]

    create table hibernate_unique_key (
         next_hi INT
    )

using System;
using System.Xml;
using System.Xml.Serialization;

namespace Test
{
  /// <summary>
  /// کلاسی جهت نمایش تعداد خواننده فید وبلاگ شما
  /// <example>CFeedBurner data = new CFeedBurner { FeedID = "fhphjt61bueu08k93ehujpu234" };
  /// MessageBox.Show(data.Circulation().ToString());</example>
  /// </summary>
  class CFeedBurner
  {
      /// <summary>
      /// آی دی فید شما زمانیکه به فید برنر لاگین کرده‌اید در تایتل صفحه مربوطه
      /// </summary>
      public string FeedID { get; set; }

      /// <summary>
      /// نگاشت فید به یک کلاس
      /// </summary>
      /// <returns>کلاس متناظر با فید</returns>
      /// <exception cref="Exception">لطفا شماره شناسایی فید را وارد کنید</exception>
      rsp deserializeFromXML()
      {
          if (FeedID == null)
              throw new Exception("لطفا شماره شناسایی فید را وارد کنید");

          XmlSerializer deserializer =
              new XmlSerializer(typeof(rsp));
          using (XmlReader reader = XmlReader.Create(
              string.Format("https://feedburner.google.com/api/awareness/1.0/GetFeedData?id={0}", FeedID)))
          {
              return (rsp)deserializer.Deserialize(reader);
          }
      }

      /// <summary>
      /// دریافت تعداد خواننده فید
      /// </summary>
      /// <returns>آمار فید</returns>
      /// <exception cref="Exception">اطلاعات فید شما قابل دریافت نیست</exception>
      public int Circulation()
      {
          rsp data = deserializeFromXML();
          if (data == null || data.feed == null || data.feed.Length == 0)
              throw new Exception("اطلاعات فید شما قابل دریافت نیست");

          if (data.feed[0].entry == null || data.feed[0].entry.Length == 0)
              throw new Exception("اطلاعات فید شما قابل پردازش نیست");

          return int.Parse(data.feed[0].entry[0].circulation);
      }
  }
}

xsd.exe GetFeedData.xml
xsd.exe GetFeedData.xsd /c

در ادامه لازم است در مرحله اعتبار سنجی و رمزگشایی توکن در سمت سرور، کلید و الگوریتم لازم را به آن معرفی کنیم تا middleware مربوطه بتواند توکن دریافتی را رمزگشایی و سپس اعتبار سنجی کند. بدین منظور در متد ConfigureServices کلاس Startup.cs خواهیم داشت:

services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
.AddJwtBearer(options =>
{
   var secretkey = Encoding.UTF8.GetBytes("LongerThan-16Char-SecretKey");
   var encryptionkey = Encoding.UTF8.GetBytes("16CharEncryptKey");

   var validationParameters = new TokenValidationParameters
   {
      ClockSkew = TimeSpan.Zero, // default: 5 min
      RequireSignedTokens = true,

      ValidateIssuerSigningKey = true,
      IssuerSigningKey = new SymmetricSecurityKey(secretkey),

      RequireExpirationTime = true,
      ValidateLifetime = true,

      ValidateAudience = true, //default : false
      ValidAudience = "MyWebsite",

      ValidateIssuer = true, //default : false
      ValidIssuer = "MyWebsite",

      TokenDecryptionKey = new SymmetricSecurityKey(encryptionkey)
   };

   options.RequireHttpsMetadata = false;
   options.SaveToken = true;
   options.TokenValidationParameters = validationParameters;
});

کد بالا مانند کد فعال سازی احراز هویت توسط JWT معمولی در ASP.NET Core است؛ با این تفاوت که:

ابتدا آرایه بایتی همان کلید رمزنگاری (encryptionkey) که قبلا توکن را با آن رمزنگاری کرده بودیم، گرفته شده و سپس توسط مقداردهی خاصیت TokenDecryptionKey کلاس TokenValidationParameters، معرفی شده است. 

ولی شاید این سؤال برایتان پیش آید که چرا الگوریتم رمزنگاری مشخص نشده است؟ پس سرور از کجا می‌فهمد که این توکن بر اساس چه الگوریتمی رمزنگاری شده است؟ 

دلیل آن این است که به هنگام تولید توکن، اسم الگوریتم مربوطه، داخل بخش header توکن نوشته می‌شود. اگر تصویر قبل را مشاهده کنید مقدار header توکن به شرح زیر است.

{
  "alg": "A128KW",
  "enc": "A128CBC-HS256",
  "typ": "JWT"
}

پس سرور بر اساس این قسمت از توکن (header)، که هیچگاه رمزنگاری نمی‌شود، می‌فهمد که توسط چه الگوریتمی باید توکن را رمزگشایی کند که در اینجا A128CBC-HS256 (اختصار AES-128-CBC و HMAC-SHA256) است.

مثال کامل و قابل اجرای این مطلب را می‌توانید از این ریپازیتوری دریافت کنید.

  if (ModelState.IsValid)
        {
            // find user by username
            var user = await _signInManager.UserManager.FindByNameAsync(Input.Username);

            // validate username/password using ASP.NET Identity
            if (user != null && (await _signInManager.CheckPasswordSignInAsync(user, Input.Password, true)) == SignInResult.Success)
            {
                await _events.RaiseAsync(new UserLoginSuccessEvent(user.UserName, user.Id, user.UserName, clientId: context?.Client.ClientId));

                // only set explicit expiration here if user chooses "remember me". 
                // otherwise we rely upon expiration configured in cookie middleware.
                AuthenticationProperties props = null;
                if (LoginOptions.AllowRememberLogin && Input.RememberLogin)
                {
                    props = new AuthenticationProperties
                    {
                        IsPersistent = true,
                        ExpiresUtc = DateTimeOffset.UtcNow.Add(LoginOptions.RememberMeLoginDuration)
                    };
                };

                // issue authentication cookie with subject ID and username
                var isuser = new IdentityServerUser(user.Id)
                {
                    DisplayName = user.UserName
                };

                await HttpContext.SignInAsync(isuser, props);

                if (context != null)
                {
                    if (context.IsNativeClient())
                    {
                        // The client is native, so this change in how to
                        // return the response is for better UX for the end user.
                        return this.LoadingPage(Input.ReturnUrl);
                    }

                    // we can trust model.ReturnUrl since GetAuthorizationContextAsync returned non-null
                    return Redirect(Input.ReturnUrl);
                }

                // request for a local page
                if (Url.IsLocalUrl(Input.ReturnUrl))
                {
                    return Redirect(Input.ReturnUrl);
                }
                else if (string.IsNullOrEmpty(Input.ReturnUrl))
                {
                    return Redirect("~/");
                }
                else
                {
                    // user might have clicked on a malicious link - should be logged
                    throw new Exception("invalid return URL");
                }
            }

            await _events.RaiseAsync(new UserLoginFailureEvent(Input.Username, "invalid credentials", clientId: context?.Client.ClientId));
            ModelState.AddModelError(string.Empty, LoginOptions.InvalidCredentialsErrorMessage);
        }