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Added MediatorPattern example
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‎MediatorPattern/ColorConsole.cs

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namespace MediatorPattern;
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public static class ColorConsole
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{
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public static void WriteLineCommandHandler(string print) => WriteLineColored(print, ConsoleColor.Blue);
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public static void WriteLineQueryHandler(string print) => WriteLineColored(print, ConsoleColor.Yellow);
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public static void WriteLineProgram(string print) => WriteLineColored(print, ConsoleColor.Green);
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public static void WriteLineRepository(string print) => WriteLineColored(print, ConsoleColor.DarkMagenta);
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private static void WriteLineColored(string toPrint, ConsoleColor color)
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{
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Console.ForegroundColor = color;
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Console.WriteLine(toPrint);
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Console.ResetColor();
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}
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}

‎MediatorPattern/Command/AddNewUserCommand.cs

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using MediatR;
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namespace MediatorPattern.Command;
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public class AddNewUserCommand : IRequest<User>
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{
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public string Name { get; set; }
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}

‎MediatorPattern/Command/AddNewUserCommandHandler.cs

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using MediatorPattern.Infrastructure;
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using MediatR;
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namespace MediatorPattern.Command;
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public class AddNewUserCommandHandler : IRequestHandler<AddNewUserCommand, User>
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{
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private readonly UserRepository _userRepository;
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public AddNewUserCommandHandler(UserRepository userRepository)
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{
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_userRepository = userRepository;
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}
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public Task<User> Handle(AddNewUserCommand request, CancellationToken cancellationToken)
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{
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ColorConsole.WriteLineCommandHandler($"Passing user '{request.Name}' to repository");
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var user = new User { Name = request.Name };
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var userFromRepo = _userRepository.AddUser(user);
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ColorConsole.WriteLineCommandHandler($"Saved user to repository and return result");
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return Task.FromResult(userFromRepo);
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}
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}

‎MediatorPattern/Command/DeleteAllUsersCommand.cs

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using MediatR;
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namespace MediatorPattern.Command;
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public class DeleteAllUsersCommand : IRequest<Unit>
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{
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}

‎MediatorPattern/Command/DeleteAllUsersCommandHandler.cs

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using MediatorPattern.Infrastructure;
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using MediatR;
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namespace MediatorPattern.Command;
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public class DeleteAllUsersCommandHandler : IRequestHandler<DeleteAllUsersCommand, Unit>
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{
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private readonly UserRepository _userRepository;
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public DeleteAllUsersCommandHandler(UserRepository userRepository)
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{
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_userRepository = userRepository;
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}
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public Task<Unit> Handle(DeleteAllUsersCommand request, CancellationToken cancellationToken)
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{
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ColorConsole.WriteLineCommandHandler($"Deleting all users");
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_userRepository.DeleteAll();
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ColorConsole.WriteLineCommandHandler($"All users deleted");
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return Task.FromResult(Unit.Value);
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}
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}

‎MediatorPattern/Domain/User.cs

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namespace MediatorPattern;
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public class User
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{
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public int Id { get; set; }
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public string Name { get; set; }
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}

‎MediatorPattern/Execution.cs

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using MediatorPattern.Command;
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using MediatorPattern.Query;
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using MediatR;
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namespace MediatorPattern;
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public class Execution
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{
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private readonly IMediator _mediator;
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public Execution(IMediator mediator)
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{
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_mediator = mediator;
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}
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public async Task RunAsync()
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{
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ColorConsole.WriteLineProgram("Creating a new user with name 'Steven'");
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var user = await _mediator.Send(new AddNewUserCommand { Name = "Steven" });
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ColorConsole.WriteLineProgram($"User has id: {user.Id}");
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Console.WriteLine();
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ColorConsole.WriteLineProgram($"Get count of users with name 'Rebecca'");
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var count = await _mediator.Send(new GetUserCountQuery { NameFilter = "Rebecca" });
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ColorConsole.WriteLineProgram($"Found {count} entries");
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Console.WriteLine();
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ColorConsole.WriteLineProgram($"Deleting all users");
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await _mediator.Send(new DeleteAllUsersCommand());
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ColorConsole.WriteLineProgram($"All users deleted");
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}
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}

‎MediatorPattern/Infrastructure/UserRepository.cs

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namespace MediatorPattern.Infrastructure;
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public class UserRepository
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{
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private readonly List<User> _users = new();
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public User AddUser(User user)
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{
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ColorConsole.WriteLineRepository($"Adding user with name: '{user.Name}'");
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var currentMaxId = !_users.Any() ? 0 : _users.Max(u => u.Id);
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user.Id = currentMaxId + 1;
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_users.Add(user);
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return user;
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}
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public int GetUserCount(string? name)
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{
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ColorConsole.WriteLineRepository($"Filtering users where name is '{name}'");
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return name == null ? _users.Count : _users.Count(u => u.Name.Contains(name));
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}
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public void DeleteAll()
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{
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ColorConsole.WriteLineRepository($"Deleting all users");
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_users.Clear();
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}
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}

‎MediatorPattern/MediatorPattern.csproj

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<Project Sdk="Microsoft.NET.Sdk">
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<PropertyGroup>
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<OutputType>Exe</OutputType>
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<TargetFramework>net6.0</TargetFramework>
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<ImplicitUsings>enable</ImplicitUsings>
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<Nullable>enable</Nullable>
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</PropertyGroup>
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<ItemGroup>
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<PackageReference Include="MediatR" Version="10.0.1" />
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<PackageReference Include="MediatR.Extensions.Microsoft.DependencyInjection" Version="10.0.1" />
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<PackageReference Include="Microsoft.Extensions.DependencyInjection" Version="6.0.0" />
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</ItemGroup>
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</Project>

‎MediatorPattern/MediatorPattern.sln

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Microsoft Visual Studio Solution File, Format Version 12.00
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Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "MediatorPattern", "MediatorPattern.csproj", "{A646458D-DD3E-49C4-91CB-6F9C1AC49B66}"
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EndProject
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Global
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GlobalSection(SolutionConfigurationPlatforms) = preSolution
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Debug|Any CPU = Debug|Any CPU
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Release|Any CPU = Release|Any CPU
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EndGlobalSection
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GlobalSection(ProjectConfigurationPlatforms) = postSolution
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{A646458D-DD3E-49C4-91CB-6F9C1AC49B66}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
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{A646458D-DD3E-49C4-91CB-6F9C1AC49B66}.Debug|Any CPU.Build.0 = Debug|Any CPU
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{A646458D-DD3E-49C4-91CB-6F9C1AC49B66}.Release|Any CPU.ActiveCfg = Release|Any CPU
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{A646458D-DD3E-49C4-91CB-6F9C1AC49B66}.Release|Any CPU.Build.0 = Release|Any CPU
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EndGlobalSection
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EndGlobal

‎MediatorPattern/Program.cs

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// See https://aka.ms/new-console-template for more information
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using System.Drawing;
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using MediatorPattern;
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using MediatorPattern.Infrastructure;
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using MediatR;
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using Microsoft.Extensions.DependencyInjection;
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Console.WriteLine("Legend:");
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ColorConsole.WriteLineCommandHandler("Command - Handlers are blue");
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ColorConsole.WriteLineQueryHandler("Query - Handlers are yellow");
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ColorConsole.WriteLineProgram("Program code is green");
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ColorConsole.WriteLineRepository("Repository code is magenta");
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Console.WriteLine("------------------------");
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Console.WriteLine();
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var serviceProvider = CreateServiceProvider();
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await serviceProvider.GetRequiredService<Execution>().RunAsync();
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ServiceProvider CreateServiceProvider()
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{
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var collection = new ServiceCollection();
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collection.AddScoped<Execution>();
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collection.AddMediatR(typeof(Program).Assembly);
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collection.AddScoped<UserRepository>();
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return collection.BuildServiceProvider();
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}

‎MediatorPattern/Query/GetUserCountQuery.cs

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using MediatR;
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namespace MediatorPattern.Query;
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public class GetUserCountQuery : IRequest<int>
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{
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public string? NameFilter { get; set; }
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}

‎MediatorPattern/Query/GetUserCountQueryHandler.cs

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using MediatorPattern.Infrastructure;
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using MediatR;
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namespace MediatorPattern.Query;
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public class GetUserCountQueryHandler : IRequestHandler<GetUserCountQuery, int>
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{
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private readonly UserRepository _userRepository;
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public GetUserCountQueryHandler(UserRepository userRepository)
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{
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_userRepository = userRepository;
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}
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public Task<int> Handle(GetUserCountQuery request, CancellationToken cancellationToken)
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{
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ColorConsole.WriteLineQueryHandler($"Getting count of users with name '{request.NameFilter}'");
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var count = _userRepository.GetUserCount(request.NameFilter);
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ColorConsole.WriteLineQueryHandler("Got count from repository and returning it back.");
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return Task.FromResult(count);
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}
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}

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