namespace DynamicSearch.Model
{
    public class Person
    {
        public Person(string name, string family, string fatherName)
        {
            Name = name;
            Family = family;
            FatherName = fatherName;
        }

        public string Name { get; set; }
        public string Family { get; set; }
        public string FatherName { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DynamicSearch.Model
{
    public class Teacher : Person
    {
        public Teacher(int id, string name, string family, string fatherName)
            : base(name, family, fatherName)
        {
            ID = id;
        }

        public int ID { get; set; }

        public override string ToString()
        {
            return string.Format("Name: {0}, Family: {1}", Name, Family);
        }
    }
}

namespace DynamicSearch.Model
{
    public class Student : Person
    {
        public Student(int stdId, Teacher teacher, string name, string family, string fatherName)
            : base(name, family, fatherName)
        {
            StdID = stdId;
            Teacher = teacher;
        }

        public int StdID { get; set; }
        public Teacher Teacher { get; set; }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using DynamicSearch.Model;

namespace DynamicSearch.Service
{
    public class StudentService
    {
        public IList<Student> GetStudents()
        {
            return new List<Student>
                {
                    new Student(1,new Teacher(1,"Ali","Rajabi","Reza"),"Mohammad","Hoeyni","Sadegh"),
                    new Student(2,new Teacher(2,"Hasan","Noori","Mohsen"),"Omid","Razavi","Ahmad"),
                };
        }
    }
}

using System;
using System.Linq.Expressions;

namespace DynamicSearch.ViewModel.Base
{
    public class AndOr
    {
        public AndOr(string name, string title,Func<Expression,Expression,Expression> func)
        {
            Title = title;
            Func = func;
            Name = name;
        }

        public string Title { get; set; }
        public Func<Expression, Expression, Expression> Func { get; set; }
        public string Name { get; set; }
    }
}

using System;

namespace DynamicSearch.ViewModel.Base
{
    public class Feild : IEquatable<Feild>
    {
        public Feild(string title, Type type, string name)
        {
            Title = title;
            Type = type;
            Name = name;
        }

        public Type Type { get; set; }
        public string Name { get; set; }
        public string Title { get; set; }
        public bool Equals(Feild other)
        {
            return other.Title == Title;
        }
    }
}

using System;
using System.Linq.Expressions;

namespace DynamicSearch.ViewModel.Base
{
    public class Operator
    {
        public enum TypesToApply
        {
            String,
            Numeric,
            Both
        }

        public Operator(string title, Func<Expression, Expression, Expression> func, TypesToApply typeToApply)
        {
            Title = title;
            Func = func;
            TypeToApply = typeToApply;
        }

        public string Title { get; set; }
        public Func<Expression, Expression, Expression> Func { get; set; }
        public TypesToApply TypeToApply { get; set; }
    }
}

using System.Collections.ObjectModel;
using System.Linq;
using System.Linq.Expressions;

namespace DynamicSearch.ViewModel.Base
{
    public abstract class SearchFilterBase<T> : BaseViewModel
    {
        protected SearchFilterBase()
        {
            var containOp = new Operator("شامل باشد", (expression, expression1) => Expression.Call(expression, typeof(string).GetMethod("Contains"), expression1), Operator.TypesToApply.String);
            var notContainOp = new Operator("شامل نباشد", (expression, expression1) =>
            {
                var contain = Expression.Call(expression, typeof(string).GetMethod("Contains"), expression1);
                return Expression.Not(contain);
            }, Operator.TypesToApply.String);
            var equalOp = new Operator("=", Expression.Equal, Operator.TypesToApply.Both);
            var notEqualOp = new Operator("<>", Expression.NotEqual, Operator.TypesToApply.Both);
            var lessThanOp = new Operator("<", Expression.LessThan, Operator.TypesToApply.Numeric);
            var greaterThanOp = new Operator(">", Expression.GreaterThan, Operator.TypesToApply.Numeric);
            var lessThanOrEqual = new Operator("<=", Expression.LessThanOrEqual, Operator.TypesToApply.Numeric);
            var greaterThanOrEqual = new Operator(">=", Expression.GreaterThanOrEqual, Operator.TypesToApply.Numeric);

            Operators = new ObservableCollection<Operator>
                {
                      equalOp, 
                      notEqualOp,
                      containOp,
                      notContainOp,
                      lessThanOp,
                      greaterThanOp,
                      lessThanOrEqual,
                      greaterThanOrEqual,
                };


            SelectedAndOr = AndOrs.FirstOrDefault(a => a.Name == "Suppress");
            SelectedFeild = Feilds.FirstOrDefault();
            SelectedOperator = Operators.FirstOrDefault(a => a.Title == "=");
        }

        public abstract IQueryable<T> GetQuarable();

        public virtual ObservableCollection<AndOr> AndOrs
        {
            get
            {
                return new ObservableCollection<AndOr>
                    {
                        new AndOr("And","و", Expression.AndAlso), 
                        new AndOr("Or","یا",Expression.OrElse),
                        new AndOr("Suppress","نادیده",(expression, expression1) => expression),
                    };
            }
        }
        public virtual ObservableCollection<Operator> Operators
        {
            get { return _operators; }
            set { _operators = value; NotifyPropertyChanged("Operators"); }
        }
        public abstract ObservableCollection<Feild> Feilds { get; }

        public bool IsOtherFilters
        {
            get { return _isOtherFilters; }
            set { _isOtherFilters = value; }
        }
        public string SearchValue
        {
            get { return _searchValue; }
            set { _searchValue = value; NotifyPropertyChanged("SearchValue"); }
        }
        public AndOr SelectedAndOr
        {
            get { return _selectedAndOr; }
            set { _selectedAndOr = value; NotifyPropertyChanged("SelectedAndOr"); NotifyPropertyChanged("SelectedFeildHasSetted"); }
        }
        public Operator SelectedOperator
        {
            get { return _selectedOperator; }
            set { _selectedOperator = value; NotifyPropertyChanged("SelectedOperator"); }
        }
        public Feild SelectedFeild
        {
            get { return _selectedFeild; }
            set
            {
                Operators = value.Type == typeof(string) ? new ObservableCollection<Operator>(Operators.Where(a => a.TypeToApply == Operator.TypesToApply.Both || a.TypeToApply == Operator.TypesToApply.String)) : new ObservableCollection<Operator>(Operators.Where(a => a.TypeToApply == Operator.TypesToApply.Both || a.TypeToApply == Operator.TypesToApply.Numeric));
                if (SelectedOperator == null)
                {
                    SelectedOperator = Operators.FirstOrDefault(a => a.Title == "=");
                }

                NotifyPropertyChanged("SelectedOperator");
                NotifyPropertyChanged("SelectedFeild");
                _selectedFeild = value;
                NotifyPropertyChanged("SelectedFeildHasSetted");
            }
        }
        public bool SelectedFeildHasSetted
        {
            get
            {
                return SelectedFeild != null &&
                       (SelectedAndOr.Name != "Suppress" || !IsOtherFilters);
            }
        }

        private ObservableCollection<Operator> _operators;
        private Feild _selectedFeild;
        private Operator _selectedOperator;
        private AndOr _selectedAndOr;
        private string _searchValue;
        private bool _isOtherFilters = true;
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using AutoMapper;

namespace DynamicSearch.ViewModel.Base
{
  public static  class ExpressionExtensions
    {
        public static List<T> CreateQuery<T>(Expression whereCallExpression, IQueryable entities)
        {
            return entities.Provider.CreateQuery<T>(whereCallExpression).ToList();
        }

        public static MethodCallExpression CreateWhereCall<T>(Expression condition, ParameterExpression pe, IQueryable entities)
        {
            var whereCallExpression = Expression.Call(
                typeof(Queryable),
                "Where",
                new[] { entities.ElementType },
                entities.Expression,
                Expression.Lambda<Func<T, bool>>(condition, new[] { pe }));
            return whereCallExpression;
        }

        public static void CreateLeftAndRightExpression<T>(string propertyName, Type type, string searchValue, ParameterExpression pe, out Expression left, out Expression right)
        {
            var typeOfNullable = type;
            typeOfNullable = typeOfNullable.IsNullableType() ? typeOfNullable.GetTypeOfNullable() : typeOfNullable;
            left = null;

            var typeMethodInfos = typeOfNullable.GetMethods();
            var parseMethodInfo = typeMethodInfos.FirstOrDefault(a => a.Name == "Parse" && a.GetParameters().Count() == 1);

            var propertyInfos = typeof(T).GetProperties();
            if (propertyName.Contains("."))
            {
                left = CreateComplexTypeExpression(propertyName, propertyInfos, pe);
            }
            else
            {
                var propertyInfo = propertyInfos.FirstOrDefault(a => a.Name == propertyName);
                if (propertyInfo != null) left = Expression.Property(pe, propertyInfo);
            }

            if (left != null) left = Expression.Convert(left, typeOfNullable);

            if (parseMethodInfo != null)
            {
                var invoke = parseMethodInfo.Invoke(searchValue, new object[] { searchValue });
                right = Expression.Constant(invoke, typeOfNullable);
            }
            else
            {
                //type is string
                right = Expression.Constant(searchValue.ToLower());
                var methods = typeof(string).GetMethods();
                var firstOrDefault = methods.FirstOrDefault(a => a.Name == "ToLower" && !a.GetParameters().Any());
                if (firstOrDefault != null) left = Expression.Call(left, firstOrDefault);
            }
        }

        public static Expression CreateComplexTypeExpression(string searchFilter, IEnumerable<PropertyInfo> propertyInfos, Expression pe)
        {
            Expression ex = null;
            var infos = searchFilter.Split('.');
            var enumerable = propertyInfos.ToList();
            for (var index = 0; index < infos.Length - 1; index++)
            {
                var propertyInfo = infos[index];
                var nextPropertyInfo = infos[index + 1];
                if (propertyInfos == null) continue;
                var propertyInfo2 = enumerable.FirstOrDefault(a => a.Name == propertyInfo);
                if (propertyInfo2 == null) continue;
                var val = Expression.Property(pe, propertyInfo2);
                var propertyInfos3 = propertyInfo2.PropertyType.GetProperties();
                var propertyInfo3 = propertyInfos3.FirstOrDefault(a => a.Name == nextPropertyInfo);
                if (propertyInfo3 != null) ex = Expression.Property(val, propertyInfo3);
            }

            return ex;
        }

        public static Expression AddOperatorExpression(Func<Expression, Expression, Expression> func, Expression left, Expression right)
        {
            return func.Invoke(left, right);
        }

        public static Expression JoinExpressions(bool isFirst, Func<Expression, Expression, Expression> func, Expression expression, Expression ex)
        {
            if (!isFirst)
            {
                return func.Invoke(expression, ex);
            }

            expression = ex;
            return expression;
        }
    }
}

using System.Collections.ObjectModel;
using System.Linq;
using DynamicSearch.Model;
using DynamicSearch.Service;
using DynamicSearch.ViewModel.Base;

namespace DynamicSearch.ViewModel
{
    public class StudentSearchFilter : SearchFilterBase<Student>
    {
        public override ObservableCollection<Feild> Feilds
        {
            get
            {
                return new ObservableCollection<Feild>
                    {
                        new Feild("نام دانش آموز",typeof(string),"Name"), 
                         new Feild("نام خانوادگی دانش آموز",typeof(string),"Family"),
                        new Feild("نام خانوادگی معلم",typeof(string),"Teacher.Name"),
                        new Feild("شماره دانش آموزی",typeof(int),"StdID"),
                    };
            }
        }

        public override IQueryable<Student> GetQuarable()
        {
            return new StudentService().GetStudents().AsQueryable();
        }
    }
}

<Window x:Class="DynamicSearch.View.MainWindow"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:viewModel="clr-namespace:DynamicSearch.ViewModel;assembly=DynamicSearch.ViewModel"
        xmlns:view="clr-namespace:DynamicSearch.View"
        mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300">
    <Window.Resources>
        <viewModel:StudentSearchViewModel x:Key="StudentSearchViewModel" />
        <view:VisibilityConverter x:Key="VisibilityConverter" />
    </Window.Resources>
    <Grid   DataContext="{StaticResource StudentSearchViewModel}">
        <WrapPanel Orientation="Vertical">
            <DataGrid AutoGenerateColumns="False" Name="asd" CanUserAddRows="False" ItemsSource="{Binding BindFilter}">
                <DataGrid.Columns>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate DataType="{x:Type viewModel:StudentSearchFilter}">
                                <ComboBox MinWidth="100"  DisplayMemberPath="Title" ItemsSource="{Binding AndOrs}" Visibility="{Binding IsOtherFilters,Converter={StaticResource VisibilityConverter}}"
                                          SelectedItem="{Binding SelectedAndOr,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn >
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate DataType="{x:Type viewModel:StudentSearchFilter}">
                                <ComboBox IsEnabled="{Binding SelectedFeildHasSetted}" MinWidth="100"   DisplayMemberPath="Title" ItemsSource="{Binding Feilds}" SelectedItem="{Binding SelectedFeild,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged }"/>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate DataType="{x:Type viewModel:StudentSearchFilter}">
                                <ComboBox MinWidth="100"  DisplayMemberPath="Title" ItemsSource="{Binding Operators}" IsEnabled="{Binding SelectedFeildHasSetted}"
                                          SelectedItem="{Binding SelectedOperator,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}" />
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                    <DataGridTemplateColumn Width="*">
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate DataType="{x:Type viewModel:StudentSearchFilter}">
                                <TextBox IsEnabled="{Binding SelectedFeildHasSetted}" MinWidth="200" Text="{Binding SearchValue,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>
                                <!--<TextBox Text="{Binding SearchValue,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>-->
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
            </DataGrid>

            <Button Content="+" HorizontalAlignment="Left" Command="{Binding AddFilter}"/>
            <Button Content="Result" Command="{Binding ExecuteSearchFilter}"/>
            <DataGrid ItemsSource="{Binding Results}">
                
            </DataGrid>
        </WrapPanel>
    </Grid>
</Window>

using System;
using System.Collections.Generic;
namespace ChapterOneProject
{
public class Patient
    {
        public Patient()
        {
            Visits = new List<Visit>();
        }

        public int Id { get; set; }
        public string Name { get; set; }
        public DateTime BirthDate { get; set; }
        //[ForeignKey("AnimalTypeId")]
        
        public AnimalType AnimalType { get; set; }
        //public int AnimalTypeId { get; set; }

        public DateTime FirstVisit { get; set; }
        public List<Visit> Visits { get; set; }
    }

public class Visit
    {
        [Key]
        public int Id { get; set; }
        public DateTime Date { get; set; }
        public String ReasonForVisit { get; set; }
        public String Outcome { get; set; }
        public Decimal Weight { get; set; }

        //[ForeignKey("PatientId")]
        //public virtual Patient Patient { get; set; }
        public int PatientId { get; set; }
    }

public class AnimalType
    {
        public int Id { get; set; }
        public string TypeName { get; set; }
    }
}

public class VetContext : DbContext
    {
        public DbSet<Patient> Patients { get; set; }
        public DbSet<Visit> Visits { get; set; }
        //public DbSet<AnimalType> AnimalTypes { get; set; }
    }

var dog = new AnimalType { TypeName = "Dog" };
            var visit = new List<Visit>
                            {
                                new Visit
                                    {
                                        Date = new DateTime(2011, 9, 1),
                                        Outcome = "Test",
                                        ReasonForVisit = "Test",
                                        Weight = 32,
                                    }
                            };
            var patient = new Patient
                              {
                                  Name = "Sampson",
                                  BirthDate = new DateTime(2008, 1, 28),
                                  AnimalType = dog,
                                  Visits = visit,
                              };
            using (var context = new VetContext())
            {
                context.Patients.Add(patient);
                context.SaveChanges();
            }

 int a = default(int);

var number = default(int); // 0
var date = default(DateTime); // DateTime.MinValue
var obj = default(object); // null

int a = default; // 0
Guid guid = default; // 00000000-0000-0000-0000-000000000000

 var ages = new[] {18, default, 50};

 var ages = new[] { default };

string s = default;
if(s == default)
{

}

int a = default;
var x = a > 0 ? default : 1.5;

    /// <summary>
    /// حساب بانکی
    /// </summary>
    public class Account
    {
        /// <summary>
        /// مشتری
        /// </summary>
        public string Customer { get; set; }
        /// <summary>
        /// موجودی حساب
        /// </summary>
        public float Balance { get; set; }
        /// <summary>
        /// وضعیت
        /// </summary>
        public bool Active { get; set; }

        public Account(string customer, float balance)
        {
            Customer = customer;
            Balance = balance;
            Active = true;
        }
        /// <summary>
        /// افزایش موجودی / واریز به حساب
        /// </summary>
        /// <param name="amount">مبلغ واریز</param>
        public void Credit(float amount)
        {
            if (!Active)
                throw new Exception("این حساب مسدود است.");
            if (amount < 0)
                throw new ArgumentOutOfRangeException("amount");
            Balance += amount;
        }
        /// <summary>
        /// کاهش موجودی / برداشت از حساب
        /// </summary>
        /// <param name="amount">مبلغ برداشت</param>
        public void Debit(float amount)
        {
            if (!Active)
                throw new Exception("این حساب مسدود است.");
            if (amount < 0)
                throw new ArgumentOutOfRangeException("amount");
            if (Balance < amount)
                throw new ArgumentOutOfRangeException("amount");
            Balance -= amount;
        }
        /// <summary>
        /// انسداد / رفع انسداد
        /// </summary>
        public void ChangeStateAccount()
        {
            Active = !Active;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var account = new Account("Ali",1000);

            account.Credit(4000);
            account.Debit(2000);
            Console.WriteLine("Current balance is ${0}", account.Balance);
            Console.ReadKey();
        }
    }

    [TestClass]
    public class UnitTest
    {
        /// <summary>
        /// تعریف حساب جدید و بررسی تمامی فرآیند‌های معمول روی حساب
        /// </summary>
        [TestMethod]
        public void Create_New_Account_And_Check_The_Process()
        {
            //Arrange
            var account = new Account("Hassan", 4000);
            var account2 = new Account("Ali", 10000);
            //Act
            account.Credit(5000);
            account2.Debit(3000);
            account.ChangeStateAccount();
            account2.Active = false;
            account2.ChangeStateAccount();
            //Assert
            Assert.AreEqual(account.Balance,9000);
            Assert.AreEqual(account2.Balance,7000);
            Assert.IsTrue(account2.Active);
            Assert.AreEqual(account.Active,false);
        }

        /// <summary>
        /// زمانی که کاربر بخواهد به یک حساب مسدود واریز کند باید جلوی آن گرفته شود.
        /// </summary>
        [TestMethod]
        [ExpectedException(typeof (Exception))]
        public void When_Deactive_Account_Wants_To_add_Credit_Should_Throw_Exception()
        {
            //Arrange
            var account = new Account("Hassan", 4000) {Active = false};
            //Act
            account.Credit(4000);
            //Assert
            //Assert is handled with ExpectedException
        }

        [TestMethod]
        [ExpectedException(typeof (ArgumentOutOfRangeException))]
        public void When_Customer_Wants_To_Debit_More_Than_Balance_Should_Throw_ArgumentOutOfRangeException()
        {
            //Arrange
            var account = new Account("Hassan", 4000);
            //Act
            account.Debit(5000);
            //Assert
            //Assert is handled with ArgumentOutOfRangeException
        }

  public class OrganizationalService : ICommandHandler<CreateUnitTypeCommand>,
                                         ICommandHandler<DeleteUnitTypeCommand>,                                    
    {
        private readonly IUnitOfWork _unitOfWork;
        private readonly IUnitTypeRepository _unitTypeRepository;
        private readonly IOrganizationUnitRepository _organizationUnitRepository;
        private readonly IOrganizationUnitDomainService _organizationUnitDomainService;

        public OrganizationalService(IUnitOfWork unitOfWork, IUnitTypeRepository unitTypeRepository, IOrganizationUnitRepository organizationUnitRepository, IOrganizationUnitDomainService organizationUnitDomainService)
        {
            _unitOfWork = unitOfWork;
            _unitTypeRepository = unitTypeRepository;
            _organizationUnitRepository = organizationUnitRepository;
            _organizationUnitDomainService = organizationUnitDomainService;
        }

    [TestClass]
    public class OrganizationServiceTest
    {
        private static OrganizationalService _organizationalService;
        private static Mock<IUnitTypeRepository> _mockUnitTypeRepository;
        private static Mock<IUnitOfWork> _mockUnitOfWork;
        private static Mock<IOrganizationUnitRepository> _mockOrganizationUnitRepository;
        private static Mock<IOrganizationUnitDomainService> _mockOrganizationUnitDomainService;

        [ClassInitialize]
        public static void ClassInit(TestContext context)
        {
            TestBootstrapper.ConfigureDependencies();
            _mockUnitOfWork = new Mock<IUnitOfWork>();
            _mockUnitTypeRepository = new Mock<IUnitTypeRepository>();
            _mockOrganizationUnitRepository = new Mock<IOrganizationUnitRepository>();
            _mockOrganizationUnitDomainService=new Mock<IOrganizationUnitDomainService>();
            _organizationalService = new OrganizationalService(_mockUnitOfWork.Object, _mockUnitTypeRepository.Object,  _mockOrganizationUnitRepository.Object,_mockOrganizationUnitDomainService.Object);
        }

        /// <summary>
        /// یک نوع واحد سازمانی را حذف مینماید
        /// </summary>
        /// <param name="command"></param>
        public void Handle(DeleteUnitTypeCommand command)
        {
            var unitType = _unitTypeRepository.FindBy(command.UnitTypeId);
            if (unitType == null)
                throw new DeleteEntityNotFoundException();

            ICanDeleteUnitTypeSpecification canDeleteUnitType = new CanDeleteUnitTypeSpecification(_organizationUnitRepository);
            if (canDeleteUnitType.IsSatisfiedBy(unitType))
                throw new UnitTypeIsUnderUsingException(unitType.Title);
            _unitTypeRepository.Remove(unitType);
        }

        /// <summary>
        /// کامند حذف نوع واحد سازمانی باید به درستی حذف کند.
        /// </summary>
        [TestMethod]
        public void DeleteUnitTypeCommand_Should_Delete_UnitType()
        {
            //Arrange
            var unitTypeId=new Guid();
            var deleteUnitTypeCommand = new DeleteUnitTypeCommand { UnitTypeId = unitTypeId };
            var unitType = new UnitType("خوشه");
            var org = new List<OrganizationUnit>();
            _mockUnitTypeRepository.Setup(d => d.FindBy(deleteUnitTypeCommand.UnitTypeId)).Returns(unitType);
            _mockUnitTypeRepository.Setup(x => x.Remove(unitType));
            _mockOrganizationUnitRepository.Setup(z => z.FindBy(unitType)).Returns(org);
            try
            {
                //Act
                _organizationalService.Handle(deleteUnitTypeCommand);
            }
            catch (Exception ex)
            {
                //Assert
                Assert.Fail(ex.Message);
            }
        }

        /// <summary>
        /// کامند حذف یک نوع واحد سازمانی باید پیش از حذف بررسی کند که این شناسه داده شده برای حذف موجود باشد.
        /// </summary>
        [TestMethod]
        [ExpectedException(typeof(DeleteEntityNotFoundException))]
        public void DeleteUnitTypeCommand_ShouldNot_Delete_When_UnitTypeId_NotExist()
        {
            //Arrange
            var unitTypeId = new Guid();
            var deleteUnitTypeCommand = new DeleteUnitTypeCommand();
            var unitType = new UnitType("خوشه");
            var org = new List<OrganizationUnit>();
            _mockUnitTypeRepository.Setup(d => d.FindBy(unitTypeId)).Returns(unitType);
            _mockUnitTypeRepository.Setup(x => x.Remove(unitType));
            _mockOrganizationUnitRepository.Setup(z => z.FindBy(unitType)).Returns(org);

            //Act
            _organizationalService.Handle(deleteUnitTypeCommand);
        }

        /// <summary>
        /// کامند حذف یک نوع واحد سازمانی نباید اجرا شود وقتی که نوع واحد برای تعریف واحد‌های سازمان استفاده شده است.
        /// </summary>
        [TestMethod]
        [ExpectedException(typeof(UnitTypeIsUnderUsingException))]
        public void DeleteUnitTypeCommand_ShouldNot_Delete_When_UnitType_Exist_but_UsedForDefineOrganizationUnit()
        {
            //Arrange
            var unitTypeId = new Guid();
            var deleteUnitTypeCommand = new DeleteUnitTypeCommand { UnitTypeId = unitTypeId };
            var unitType = new UnitType("خوشه");
            var org = new List<OrganizationUnit>()
            {
                new OrganizationUnit("مدیریت یک", unitType, null),
                new OrganizationUnit("مدیریت دو", unitType, null)
            };
            _mockUnitTypeRepository.Setup(d => d.FindBy(deleteUnitTypeCommand.UnitTypeId)).Returns(unitType);
            _mockUnitTypeRepository.Setup(x => x.Remove(unitType));
            _mockOrganizationUnitRepository.Setup(z => z.FindBy(unitType)).Returns(org);

            //Act
            _organizationalService.Handle(deleteUnitTypeCommand);
        }

static async IAsyncEnumerable<int> RangeAsync(int start, int count)
{
  for (int i = 0; i < count; i++)
  {
    await Task.Delay(i);
    yield return start + i;
  }
}

    [ApiController]
    [Route("[controller]")]
    public class CustomerController : ControllerBase
    {
        private readonly IDictionary<int, Customer> _customers;
        private void FillCustomerFromMemory(int countOfCustomer)
        {
            for (int CustomerId = 1; CustomerId <= countOfCustomer; CustomerId++)
            {
                _customers.Add(key: CustomerId, new Customer($"name_{CustomerId}", CustomerId));
            }
        }
        public CustomerController()
        {
            _customers = new Dictionary<int, Customer>();
            FillCustomerFromMemory(countOfCustomer : 100);
        }
        [HttpGet]
        public async Task<IEnumerable<Customer>> Get()
        {
            var output = new List<Customer>();
            while (_customers.Any(_ => _.Key % 10 == 0))
            {
                var customer = _customers.First(_ => _.Key % 10 == 0);
                output.Add(new Customer(customer.Value.Name, customer.Key));
                await Task.Delay(500);
                _customers.Remove(customer);
            }
            return output;
        }

        public class Customer
        {
            public int Id { get; private set; }

            public string Name { get; private set; }
            public Customer(string name, int id)
            {
                Name = name;
                Id = id;
            }
        }
    }

  [HttpGet]
        public async IAsyncEnumerable<Customer> Get()
        {
            while (_customers.Any(_ => _.Key % 10 == 0))
            {
                var customer = _customers.First(_ => _.Key % 10 == 0);
                yield return new Customer(customer.Value.Name, customer.Key);
                _customers.Remove(customer);
                await Task.Delay(500);
            }
        }

const int TARGET = 80;
var _httpClient = new HttpClient();
using (var response = await _httpClient.GetAsync(
    "https://localhost:7284/customer",
     HttpCompletionOption.ResponseHeadersRead))
{
    var stream = await response.Content.ReadAsStreamAsync();

    var _jsonSerializerSettings = new JsonSerializerSettings();
    var _serializer = Newtonsoft.Json.JsonSerializer.Create(_jsonSerializerSettings);

    using TextReader textReader = new StreamReader(stream);
    using JsonReader jsonReader = new JsonTextReader(textReader);

    await using (stream.ConfigureAwait(false))
    {
        await jsonReader.ReadAsync().ConfigureAwait(false);
        while (await jsonReader.ReadAsync().ConfigureAwait(false) &&
               jsonReader.TokenType != JsonToken.EndArray)
        {
            Customer customer = _serializer!.Deserialize<Customer>(jsonReader);
            if (customer.Id == TARGET)
            {
                Console.WriteLine(customer.Id + " : " + customer.Name);
                break;
            }
        }
    }
}

[HttpGet]
        public async IAsyncEnumerable<Customer> Get(CancellationToken cancellationToken)
        {
            while (!cancellationToken.IsCancellationRequested && _customers.Any(_ => _.Key % 10 == 0))
            {
                var customer = _customers.First(_ => _.Key % 10 == 0);
                yield return new Customer(customer.Value.Name, customer.Key);
                _customers.Remove(customer);
                await Task.Delay(500,cancellationToken);
            }
        }

const int TARGET = 80;
var _httpClient = new HttpClient();
var _cancelationTokenSource = new CancellationTokenSource();

using (var response = await _httpClient.GetAsync(
    "https://localhost:7284/customer",
     HttpCompletionOption.ResponseHeadersRead,
     _cancelationTokenSource.Token))
{
    var stream = await response.Content.ReadAsStreamAsync(_cancelationTokenSource.Token);

    var _jsonSerializerSettings = new JsonSerializerSettings();
    var _serializer = Newtonsoft.Json.JsonSerializer.Create(_jsonSerializerSettings);

    using TextReader textReader = new StreamReader(stream);
    using JsonReader jsonReader = new JsonTextReader(textReader);

    await using (stream.ConfigureAwait(false))
    {
        await jsonReader.ReadAsync(_cancelationTokenSource.Token).ConfigureAwait(false);
        while (await jsonReader.ReadAsync(_cancelationTokenSource.Token).ConfigureAwait(false) &&
               jsonReader.TokenType != JsonToken.EndArray)
        {
            Customer customer = _serializer!.Deserialize<Customer>(jsonReader);
            if (customer.Id == TARGET)
            {
                Console.WriteLine(customer.Id + " : " + customer.Name);
                _cancelationTokenSource.Cancel();
                break;
            }
        }
    }
}

  PM> Install-Package RazorGenerator.Mvc

  PM> Enable-RazorGenerator

 Copy "$(ProjectDir)$(OutDir)$(TargetName).*" "$(SolutionDir)MvcPluginMasterApp\bin\"

using System.Web.Mvc;
 
namespace MvcPluginMasterApp.Plugin1.Areas.NewsArea
{
    public class NewsAreaAreaRegistration : AreaRegistration
    {
        public override string AreaName
        {
            get
            {
                return "NewsArea";
            }
        }
 
        public override void RegisterArea(AreaRegistrationContext context)
        {
            context.MapRoute(
                "NewsArea_default",
                "NewsArea/{controller}/{action}/{id}",
                // تکمیل نام کنترلر پیش فرض
                new { controller = "Home", action = "Index", id = UrlParameter.Optional },
                // مشخص کردن فضای نام مرتبط جهت جلوگیری از تداخل با سایر قسمت‌های برنامه
                namespaces: new[] { string.Format("{0}.Controllers", this.GetType().Namespace) }
            );
        }
    }
}

using System.Web.Mvc;
using System.Web.Routing;
 
namespace MvcPluginMasterApp
{
    public class RouteConfig
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
 
            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional },
                // مشخص کردن فضای نام مرتبط جهت جلوگیری از تداخل با سایر قسمت‌های برنامه
                namespaces: new[] { string.Format("{0}.Controllers", typeof(RouteConfig).Namespace) }
            );
        }
    }
}

using System;
using System.Reflection;
using System.Web.Optimization;
using System.Web.Routing;
using StructureMap;
 
namespace MvcPluginMasterApp.PluginsBase
{
    public interface IPlugin
    {
        EfBootstrapper GetEfBootstrapper();
        MenuItem GetMenuItem(RequestContext requestContext);
        void RegisterBundles(BundleCollection bundles);
        void RegisterRoutes(RouteCollection routes);
        void RegisterServices(IContainer container);
    }
 
    public class EfBootstrapper
    {
        /// <summary>
        /// Assemblies containing EntityTypeConfiguration classes.
        /// </summary>
        public Assembly[] ConfigurationsAssemblies { get; set; }
 
        /// <summary>
        /// Domain classes.
        /// </summary>
        public Type[] DomainEntities { get; set; }
 
        /// <summary>
        /// Custom Seed method.
        /// </summary>
        //public Action<IUnitOfWork> DatabaseSeeder { get; set; }
    }
 
    public class MenuItem
    {
        public string Name { set; get; }
        public string Url { set; get; }
    }
}

PM> install-package EntityFramework
PM> install-package Microsoft.AspNet.Web.Optimization
PM> install-package structuremap.web

using System.Web.Mvc;
using System.Web.Optimization;
using System.Web.Routing;
using MvcPluginMasterApp.PluginsBase;
using StructureMap;
 
namespace MvcPluginMasterApp.Plugin1
{
    public class Plugin1 : IPlugin
    {
        public EfBootstrapper GetEfBootstrapper()
        {
            return null;
        }
 
        public MenuItem GetMenuItem(RequestContext requestContext)
        {
            return new MenuItem
            {
                Name = "Plugin 1",
                Url = new UrlHelper(requestContext).Action("Index", "Home", new { area = "NewsArea" })
            };
        }
 
        public void RegisterBundles(BundleCollection bundles)
        {
            //todo: ...
        }
 
        public void RegisterRoutes(RouteCollection routes)
        {
            //todo: add custom routes.
        }
 
        public void RegisterServices(IContainer container)
        {
            // todo: add custom services.
 
            container.Configure(cfg =>
            {
                //cfg.For<INewsService>().Use<EfNewsService>();
            });
        }
    }
}

using System;
using System.IO;
using System.Threading;
using System.Web;
using MvcPluginMasterApp.PluginsBase;
using StructureMap;
using StructureMap.Graph;
 
namespace MvcPluginMasterApp.IoCConfig
{
    public static class SmObjectFactory
    {
        private static readonly Lazy<Container> _containerBuilder =
            new Lazy<Container>(defaultContainer, LazyThreadSafetyMode.ExecutionAndPublication);
 
        public static IContainer Container
        {
            get { return _containerBuilder.Value; }
        }
 
        private static Container defaultContainer()
        {
            return new Container(cfg =>
            {
                cfg.Scan(scanner =>
                {
                    scanner.AssembliesFromPath(
                        path: Path.Combine(HttpRuntime.AppDomainAppPath, "bin"),
                            // یک اسمبلی نباید دوبار بارگذاری شود
                        assemblyFilter: assembly =>
                        {
                            return !assembly.FullName.Equals(typeof(IPlugin).Assembly.FullName);
                        });
 
                    scanner.WithDefaultConventions(); //Connects 'IName' interface to 'Name' class automatically.
                    scanner.AddAllTypesOf<IPlugin>().NameBy(item => item.FullName);
                });
            });
        }
    }
}

PM> install-package EntityFramework
PM> install-package structuremap.web

using System.Linq;
using System.Web.Optimization;
using System.Web.Routing;
using MvcPluginMasterApp;
using MvcPluginMasterApp.IoCConfig;
using MvcPluginMasterApp.PluginsBase;
 
[assembly: WebActivatorEx.PostApplicationStartMethod(typeof(PluginsStart), "Start")]
 
namespace MvcPluginMasterApp
{
    public static class PluginsStart
    {
        public static void Start()
        {
            var plugins = SmObjectFactory.Container.GetAllInstances<IPlugin>().ToList();
            foreach (var plugin in plugins)
            {
                plugin.RegisterServices(SmObjectFactory.Container);
                plugin.RegisterRoutes(RouteTable.Routes);
                plugin.RegisterBundles(BundleTable.Bundles);
            }
        }
    }
}

@using MvcPluginMasterApp.IoCConfig
@using MvcPluginMasterApp.PluginsBase
@{
    var plugins = SmObjectFactory.Container.GetAllInstances<IPlugin>().ToList();
}
 
@foreach (var plugin in plugins)
{
    var menuItem = plugin.GetMenuItem(this.Request.RequestContext);
    <li>
        <a href="@menuItem.Url">@menuItem.Name</a>
    </li>
}

<div class="navbar navbar-inverse navbar-fixed-top">
    <div class="container">
        <div class="navbar-header">
            <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
                <span class="icon-bar"></span>
            </button>
            @Html.ActionLink("MvcPlugin Master App", "Index", "Home", new { area = "" }, new { @class = "navbar-brand" })
        </div>
        <div class="navbar-collapse collapse">
            <ul class="nav navbar-nav">
                <li>@Html.ActionLink("Master App/Home", "Index", "Home", new {area = ""}, null)</li>
                @{ Html.RenderPartial("_PluginsMenu"); }
            </ul>
        </div>
    </div>
</div>

<input dir="ltr" class="form-control input-validation-error" 
type="email" 
data-val="true" 
data-val-email="'آدرس ایمیل' is not a valid email address." 
data-val-remote="این آدرس ایمیل هم اکنون مورد استفاده‌است" 
data-val-remote-url="/Home/ValidateUniqueEmail" 
data-val-required="'آدرس ایمیل' must not be empty." 
id="Email" 
name="Email" 
>

using System.ComponentModel.DataAnnotations;

namespace FluentValidationSample.Models
{
    public class UserModel
    {
        [Display(Name = "نام کاربری")]
        public string Username { get; set; }

        [Display(Name = "سن")]
        public int Age { get; set; }

        [Display(Name = "سابقه کار")]
        public int Experience { get; set; }

        [DataType(DataType.EmailAddress)]
        [Display(Name = "آدرس ایمیل")]
        public string Email { get; set; }
    }
}

using System.Linq;

namespace FluentValidationSample.Services
{
    public interface IUsersService
    {
        bool IsUniqueEmail(string emailAddress);
    }

    public class UsersService : IUsersService
    {
        public bool IsUniqueEmail(string emailAddress)
        {
            string[] registedEmails = {
                "email@site.com",
                "test@gmail.com"
            };
            return !registedEmails.Contains(emailAddress);
        }
    }
}

namespace FluentValidationSample.Web
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IUsersService, UsersService>();

using FluentValidation.Validators;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public class UniqueEmailValidator : PropertyValidator
    {
        private readonly IUsersService _usersService;

        public UniqueEmailValidator(IUsersService usersService)
                : base("این آدرس ایمیل هم اکنون مورد استفاده‌است")
        {
            _usersService = usersService;
        }

        protected override bool IsValid(PropertyValidatorContext context)
        {
            return context.PropertyValue != null &&
                    _usersService.IsUniqueEmail((string)context.PropertyValue);
        }
    }
}

using FluentValidation;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public static class CustomValidatorExtensions
    {
        public static IRuleBuilderOptions<T, string> UniqueEmail<T>(
            this IRuleBuilder<T, string> ruleBuilder, IUsersService usersService)
        {
            return ruleBuilder.SetValidator(new UniqueEmailValidator(usersService));
        }
    }
}

using FluentValidation;
using FluentValidationSample.Models;
using FluentValidationSample.Services;

namespace FluentValidationSample.ModelsValidations
{
    public class UserModelValidator : AbstractValidator<UserModel>
    {
        public UserModelValidator(IUsersService usersService)
        {
            RuleFor(x => x.Username).NotNull();
            RuleFor(x => x.Age).NotNull();
            RuleFor(x => x.Experience).LowerThan(nameof(UserModel.Age)).NotNull();
            RuleFor(x => x.Email).EmailAddress().NotNull().UniqueEmail(usersService);
        }
    }
}

using FluentValidation;
using FluentValidation.AspNetCore;
using FluentValidation.Internal;
using FluentValidation.Resources;
using FluentValidation.Validators;
using Microsoft.AspNetCore.Mvc.ModelBinding.Validation;

namespace FluentValidationSample.ModelsValidations
{
    public class RemoteClientValidator : ClientValidatorBase
    {
        public string RemoteUrl { set; get; }

        public RemoteClientValidator(PropertyRule rule, IPropertyValidator validator) :
            base(rule, validator)
        {
        }

        public override void AddValidation(ClientModelValidationContext context)
        {
            MergeAttribute(context.Attributes, "data-val", "true");
            MergeAttribute(context.Attributes, "data-val-remote", GetErrorMessage(context));
            MergeAttribute(context.Attributes, "data-val-remote-url", RemoteUrl);
        }

        private string GetErrorMessage(ClientModelValidationContext context)
        {
            var formatter = ValidatorOptions.MessageFormatterFactory().AppendPropertyName(Rule.GetDisplayName());
            string messageTemplate;
            try
            {
                messageTemplate = Validator.Options.ErrorMessageSource.GetString(null);
            }
            catch (FluentValidationMessageFormatException)
            {
                messageTemplate = ValidatorOptions.LanguageManager.GetStringForValidator<NotEmptyValidator>();
            }
            return formatter.BuildMessage(messageTemplate);
        }
    }
}

<input dir="ltr" class="form-control input-validation-error" 
type="email" 
data-val="true" 
data-val-email="'آدرس ایمیل' is not a valid email address." 
data-val-remote="این آدرس ایمیل هم اکنون مورد استفاده‌است" 
data-val-remote-url="/Home/ValidateUniqueEmail" 
data-val-required="'آدرس ایمیل' must not be empty." 
id="Email" 
name="Email" 
>

namespace FluentValidationSample.Web
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IUsersService, UsersService>();

            services.AddControllersWithViews().AddFluentValidation(
                fv =>
                {
                    fv.RegisterValidatorsFromAssembly(Assembly.GetExecutingAssembly());
                    fv.RegisterValidatorsFromAssemblyContaining<RegisterModelValidator>();
                    fv.RunDefaultMvcValidationAfterFluentValidationExecutes = false;

                    fv.ConfigureClientsideValidation(clientSideValidation =>
                    {
                        // ...

                        clientSideValidation.Add(
                            validatorType: typeof(UniqueEmailValidator),
                            factory: (context, rule, validator) =>
                                        new RemoteClientValidator(rule, validator)
                                        {
                                            RemoteUrl = "/Home/ValidateUniqueEmail"
                                        });
                    });
                }
            );
        }

namespace FluentValidationSample.Web.Controllers
{
    public class HomeController : Controller
    {
        private readonly IUsersService _usersService;

        public HomeController(IUsersService usersService)
        {
            _usersService = usersService;
        }

         // ...

        public IActionResult ValidateUniqueEmail(string email)
        {
            return Ok(_usersService.IsUniqueEmail(email));
        }
    }
}

<script src="~/lib/jquery/dist/jquery.min.js"></script>
<script src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"></script>
<script src="~/lib/jquery-validation/dist/jquery.validate.js"></script>
<script src="~/lib/jquery-validation-unobtrusive/jquery.validate.unobtrusive.js"></script>
<script src="~/js/site.js" asp-append-version="true"></script>

• struct: نوع آرگومان ارسالی باید value-type باشد؛ بجز مقادیر غیر NULL.

class C<T> where T : struct {} // value type

• class: نوع آرگومان ارسالی باید reference-type (کلاس، اینترفیس، عامل، آرایه) باشد.

class D<T> where T : class {} // reference type

• ()new: آرگومان ارسالی باید یک سازنده عمومی بدون پارامتر باشد. وقتی این محدوده کننده را با سایر محدود کننده‌ها به صورت همزمان استفاده می‌کنید، این محدوده کننده باید در آخر ذکر شود.

class H<T> where T : new() {} // no parameter constructor

public void MyMethod< T >()
       where T : IComparable, MyBaseClass, new ()
{
  ...
}

• <base class name>: نوع آرگومان ارسالی باید از کلاس ذکر شده یا کلاس مشتق شده آن باشد.

class B {}
class E<T> where T : B {} // be/derive from base class

• <interface name>: نوع آرگومان ارسالی باید اینترفیس ذکر شده یا پیاده ساز آن اینترفیس باشد.

interface I {}
class G<T> where T : I {} // be/implement interface

• U: نوع آرگومان ارسالی باید از نوع یا مشتق شده U باشد.

class F<T, U> where T : U {} // be/derive from U

1. Runtime casting
2. استفاده از محدود کننده‌ها

namespace DNT.IDP
{
    public static class Config
    {
        public static List<TestUser> GetUsers()
        {
            return new List<TestUser>
            {
                new TestUser
                {
                    Username = "User 1",
                    // ...

                    Claims = new List<Claim>
                    {
    // ...
                        new Claim("subscriptionlevel", "PayingUser"),
                        new Claim("country", "ir")
                    }
                },
                new TestUser
                {
                    Username = "User 2",
// ...

                    Claims = new List<Claim>
                    {
    // ...
                        new Claim("subscriptionlevel", "FreeUser"),
                        new Claim("country", "be")
                    }
                }
            };
        }

namespace DNT.IDP
{
    public static class Config
    {
        // identity-related resources (scopes)
        public static IEnumerable<IdentityResource> GetIdentityResources()
        {
            return new List<IdentityResource>
            {
   // ...     
                new IdentityResource(
                    name: "country",
                    displayName: "The country you're living in",
                    claimTypes: new List<string> { "country" }),
                new IdentityResource(
                    name: "subscriptionlevel",
                    displayName: "Your subscription level",
                    claimTypes: new List<string> { "subscriptionlevel" })
            };
        }

namespace DNT.IDP
{
    public static class Config
    {
        public static IEnumerable<Client> GetClients()
        {
            return new List<Client>
            {
                new Client
                {
                    ClientName = "Image Gallery",
// ...
                    AllowedScopes =
                    {
    // ...
                        "country",
                        "subscriptionlevel"
                    }
// ...
                }
             };
        }
    }

options.Scope.Add("subscriptionlevel");
options.Scope.Add("country");

options.ClaimActions.MapUniqueJsonKey(claimType: "role", jsonKey: "role");
options.ClaimActions.MapUniqueJsonKey(claimType: "subscriptionlevel", jsonKey: "subscriptionlevel");
options.ClaimActions.MapUniqueJsonKey(claimType: "country", jsonKey: "country");

namespace ImageGallery.MvcClient.WebApp
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthorization(options =>
            {
                options.AddPolicy(
                   name: "CanOrderFrame",
                   configurePolicy: policyBuilder =>
                    {
                        policyBuilder.RequireAuthenticatedUser();
                        policyBuilder.RequireClaim(claimType: "country", requiredValues: "ir");
                        policyBuilder.RequireClaim(claimType: "subscriptionlevel", requiredValues: "PayingUser");
                    });
            });

@if(User.IsInRole("PayingUser"))
{
  <li><a asp-area="" asp-controller="Gallery" asp-action="AddImage">Add an image</a></li>
  <li><a asp-area="" asp-controller="Gallery" asp-action="OrderFrame">Order a framed picture</a></li>
}

@using Microsoft.AspNetCore.Authorization
@inject IAuthorizationService AuthorizationService

@if (User.IsInRole("PayingUser"))
{
  <li><a asp-area="" asp-controller="Gallery" asp-action="AddImage">Add an image</a></li>
}
@if ((await AuthorizationService.AuthorizeAsync(User, "CanOrderFrame")).Succeeded)
{
  <li><a asp-area="" asp-controller="Gallery" asp-action="OrderFrame">Order a framed picture</a></li>
}

namespace ImageGallery.MvcClient.WebApp.Controllers
{
    [Authorize]
    public class GalleryController : Controller
    {
        [Authorize(Policy = "CanOrderFrame")]
        public async Task<IActionResult> OrderFrame()
        {

using System;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.Logging;

namespace ImageGallery.WebApi.Services
{
    public class MustOwnImageRequirement : IAuthorizationRequirement
    {
    }

    public class MustOwnImageHandler : AuthorizationHandler<MustOwnImageRequirement>
    {
        private readonly IImagesService _imagesService;
        private readonly ILogger<MustOwnImageHandler> _logger;

        public MustOwnImageHandler(
            IImagesService imagesService,
            ILogger<MustOwnImageHandler> logger)
        {
            _imagesService = imagesService;
            _logger = logger;
        }

        protected override async Task HandleRequirementAsync(
            AuthorizationHandlerContext context, MustOwnImageRequirement requirement)
        {
            var filterContext = context.Resource as AuthorizationFilterContext;
            if (filterContext == null)
            {
                context.Fail();
                return;
            }

            var imageId = filterContext.RouteData.Values["id"].ToString();
            if (!Guid.TryParse(imageId, out Guid imageIdAsGuid))
            {
                _logger.LogError($"`{imageId}` is not a Guid.");
                context.Fail();
                return;
            }

            var subClaim = context.User.Claims.FirstOrDefault(c => c.Type == "sub");
            if (subClaim == null)
            {
                _logger.LogError($"User.Claims don't have the `sub` claim.");
                context.Fail();
                return;
            }

            var ownerId = subClaim.Value;
            if (!await _imagesService.IsImageOwnerAsync(imageIdAsGuid, ownerId))
            {
                _logger.LogError($"`{ownerId}` is not the owner of `{imageIdAsGuid}` image.");
                context.Fail();
                return;
            }

            // all checks out
            context.Succeed(requirement);
        }
    }
}

<Project Sdk="Microsoft.NET.Sdk">
  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="2.1.0" />
    <PackageReference Include="Microsoft.AspNetCore.Authorization" Version="2.1.1.0" />
    <PackageReference Include="Microsoft.AspNetCore.Mvc.Abstractions" Version="2.1.1.0" />
  </ItemGroup>
</Project>

public class MustOwnImageRequirement : IAuthorizationRequirement
{
}

namespace ImageGallery.WebApi.WebApp
{
    public class Startup
    {
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddAuthorization(authorizationOptions =>
            {
                authorizationOptions.AddPolicy(
                   name: "MustOwnImage",
                   configurePolicy: policyBuilder =>
                    {
                        policyBuilder.RequireAuthenticatedUser();
                        policyBuilder.AddRequirements(new MustOwnImageRequirement());
                    });
            });
            services.AddScoped<IAuthorizationHandler, MustOwnImageHandler>();

[Authorize(Policy ="MustOwnImage")]

namespace ImageGallery.WebApi.WebApp.Controllers
{
    [Route("api/images")]
    [Authorize]
    public class ImagesController : Controller
    {
        [HttpGet("{id}", Name = "GetImage")]
        [Authorize("MustOwnImage")]
        public async Task<IActionResult> GetImage(Guid id)
        {
        }

        [HttpDelete("{id}")]
        [Authorize("MustOwnImage")]
        public async Task<IActionResult> DeleteImage(Guid id)
        {
        }

        [HttpPut("{id}")]
        [Authorize("MustOwnImage")]
        public async Task<IActionResult> UpdateImage(Guid id, [FromBody] ImageForUpdateModel imageForUpdate)
        {
        }
    }
}