PM> Install-Package Microsoft.AspNet.Identity.Samples -Pre

This is the first of an eight part series where I am joined by Phil Japikse to discuss design patterns. A design pattern is a best practice you can use in your code to solve a common problem.  In this episode, Phil demonstrates the Command and Memento patterns. 

Episodes in this series:

• Command/Memento patterns (this episode)
• Strategy pattern
• Template Method pattern (to be published 7/20)
• Observer/Publish-Subscribe patterns (to be published 7/25)
• Singleton pattern (to be published 8/8)
• Factory patterns (to be published 8/10)
• Adapter/Facade patterns (to be published 8/15)
• Decorator pattern (to be published 8/17) 

public class TravelAgent
{
    public TravelAgent()
    {
        this.Bookings = new HashSet<Booking>();
    }

    public int AgentId { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Booking> Bookings { get; set; }
}

public class Booking
{
    public int BookingId { get; set; }
    public int AgentId { get; set; }
    public string Customer { get; set; }
    public DateTime BookingDate { get; set; }
    public bool Paid { get; set; }
    public virtual TravelAgent TravelAgent { get; set; }
}

<connectionStrings>
  <add name="Recipe3ConnectionString"
    connectionString="Data Source=.;
    Initial Catalog=EFRecipes;
    Integrated Security=True;
    MultipleActiveResultSets=True"
    providerName="System.Data.SqlClient" />
</connectionStrings>

protected void Application_Start()
{
    // Disable Entity Framework Model Compatibilty
    Database.SetInitializer<Recipe1Context>(null);

    // The bidirectional navigation properties between related entities
    // create a self-referencing loop that breaks Web API's effort to
    // serialize the objects as JSON. By default, Json.NET is configured
    // to error when a reference loop is detected. To resolve problem,
    // simply configure JSON serializer to ignore self-referencing loops.
    GlobalConfiguration.Configuration.Formatters.JsonFormatter
        .SerializerSettings.ReferenceLoopHandling =
        Newtonsoft.Json.ReferenceLoopHandling.Ignore;
    ...
}

public static void Register(HttpConfiguration config)
{
    config.Routes.MapHttpRoute(
      name: "ActionMethodSave",
      routeTemplate: "api/{controller}/{action}/{id}",
      defaults: new { id = RouteParameter.Optional });
}

internal class Program
{
    private HttpClient _client;
    private TravelAgent _agent1, _agent2;
    private Booking _booking1, _booking2, _booking3;
    private HttpResponseMessage _response;

    private static void Main()
    {
        Task t = Run();
        t.Wait();
        Console.WriteLine("\nPress <enter> to continue...");
        Console.ReadLine();
    }

    private static async Task Run()
    {
        var program = new Program();
        program.ServiceSetup();
        // do not proceed until clean-up is completed
        await program.CleanupAsync();
        program.CreateFirstAgent();
        // do not proceed until agent is created
        await program.AddAgentAsync();
        program.CreateSecondAgent();
        // do not proceed until agent is created
        await program.AddSecondAgentAsync();
        program.ModifyAgent();
        // do not proceed until agent is updated
        await program.UpdateAgentAsync();
        // do not proceed until agents are fetched
        await program.FetchAgentsAsync();
    }

    private void ServiceSetup()
    {
        // set up infrastructure for Web API call
        _client = new HttpClient {BaseAddress = new Uri("http://localhost:6687/")};
        // add Accept Header to request Web API content negotiation to return resource in JSON format
        _client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
    }

    private async Task CleanupAsync()
    {
        // call cleanup method in service
        _response = await _client.DeleteAsync("api/travelagent/cleanup/");
    }

    private void CreateFirstAgent()
    {
        // create new Travel Agent and booking
        _agent1 = new TravelAgent {Name = "John Tate"};
        _booking1 = new Booking
        {
            Customer = "Karen Stevens",
            Paid = false,
            BookingDate = DateTime.Parse("2/2/2010")
        };

        _booking2 = new Booking
        {
            Customer = "Dolly Parton",
            Paid = true,
            BookingDate = DateTime.Parse("3/10/2010")
        };
  
        _agent1.Bookings.Add(_booking1);
        _agent1.Bookings.Add(_booking2);
    }

    private async Task AddAgentAsync()
    {
        // call generic update method in Web API service to add agent and bookings
        _response = await _client.PostAsync("api/travelagent/update/",
            _agent1, new JsonMediaTypeFormatter());

        if (_response.IsSuccessStatusCode)
        {
            // capture newly created travel agent from service, which will include
            // database-generated Ids for each entity
            _agent1 = await _response.Content.ReadAsAsync<TravelAgent>();
            _booking1 = _agent1.Bookings.FirstOrDefault(x => x.Customer == "Karen Stevens");
            _booking2 = _agent1.Bookings.FirstOrDefault(x => x.Customer == "Dolly Parton");

            Console.WriteLine("Successfully created Travel Agent {0} and {1} Booking(s)",
            _agent1.Name, _agent1.Bookings.Count);
        }
        else
            Console.WriteLine("{0} ({1})", (int) _response.StatusCode, _response.ReasonPhrase);
    }

    private void CreateSecondAgent()
    {
        // add new agent and booking
        _agent2 = new TravelAgent {Name = "Perry Como"};
        _booking3 = new Booking {
            Customer = "Loretta Lynn",
            Paid = true,
            BookingDate = DateTime.Parse("3/15/2010")};
        _agent2.Bookings.Add(_booking3);
    }

    private async Task AddSecondAgentAsync()
    {
        // call generic update method in Web API service to add agent and booking
        _response = await _client.PostAsync("api/travelagent/update/", _agent2, new JsonMediaTypeFormatter());

        if (_response.IsSuccessStatusCode)
        {
            // capture newly created travel agent from service
            _agent2 = await _response.Content.ReadAsAsync<TravelAgent>();
            _booking3 = _agent2.Bookings.FirstOrDefault(x => x.Customer == "Loretta Lynn");
            Console.WriteLine("Successfully created Travel Agent {0} and {1} Booking(s)",
                _agent2.Name, _agent2.Bookings.Count);
        }
        else
            Console.WriteLine("{0} ({1})", (int) _response.StatusCode, _response.ReasonPhrase);
    }

    private void ModifyAgent()
    {
        // modify agent 2 by changing agent name and assigning booking 1 to him from agent 1
        _agent2.Name = "Perry Como, Jr.";
        _agent2.Bookings.Add(_booking1);
    }

    private async Task UpdateAgentAsync()
    {
        // call generic update method in Web API service to update agent 2
        _response = await _client.PostAsync("api/travelagent/update/", _agent2, new JsonMediaTypeFormatter());
        if (_response.IsSuccessStatusCode)
        {
            // capture newly created travel agent from service, which will include Ids
            _agent1 = _response.Content.ReadAsAsync<TravelAgent>().Result;
            Console.WriteLine("Successfully updated Travel Agent {0} and {1} Booking(s)", _agent1.Name, _agent1.Bookings.Count);
        }
        else
            Console.WriteLine("{0} ({1})", (int) _response.StatusCode, _response.ReasonPhrase);
    }

    private async Task FetchAgentsAsync()
    {
        // call Get method on service to fetch all Travel Agents and Bookings
        _response = _client.GetAsync("api/travelagent/retrieve").Result;
        if (_response.IsSuccessStatusCode)
        {
            // capture newly created travel agent from service, which will include Ids
            var agents = await _response.Content.ReadAsAsync<IEnumerable<TravelAgent>>();

            foreach (var agent in agents)
            {
                Console.WriteLine("Travel Agent {0} has {1} Booking(s)", agent.Name, agent.Bookings.Count());
            }
        }
        else
            Console.WriteLine("{0} ({1})", (int) _response.StatusCode, _response.ReasonPhrase);
    }
}

Security Advisory Notices

CVE-2019-1077 Visual Studio Extension Auto Update Vulnerability

An elevation of privilege vulnerability exists when the Visual Studio Extension auto-update process improperly performs certain file operations. An attacker who successfully exploited this vulnerability could delete files in arbitrary locations. To exploit this vulnerability, an attacker would require unprivileged access to a vulnerable system. The security update addresses the vulnerability by securing locations the Visual Studio Extension auto-update performs file operations in.

CVE-2019-1075 ASP.NET Core Spoofing Vulnerability

A spoofing vulnerability exists in ASP.NET Core that could lead to an open redirect. An attacker who successfully exploited the vulnerability could redirect a targeted user to a malicious website. To exploit the vulnerability, an attacker could send a link that has a specially crafted URL and convince the user to click the link.

The security update addresses the vulnerability by correcting how ASP.NET Core parses URLs. Details can be found in the .NET Core release notes.

CVE-2019-1113 WorkflowDesigner XOML deserialization allows code execution

A XOML file referencing certain types could cause random code to be executed when the XOML file is opened in Visual Studio. There is now a restriction on what types are allowed to be used in XOML files. If a XOML file containing one of the newly unauthorized types is opened, a message is displayed explaining that the type is unauthorized.

For further information, please refer to https://support.microsoft.com/en-us/help/4512190/remote-code-execution-vulnerability-if-types-are-specified-in-xoml.

• Microsoft.Data.Sqlite
• Microsoft.Data.Sqlite.Core
• Microsoft.EntityFrameworkCore.Sqlite
• Microsoft.EntityFrameworkCore.Sqlite.Core
• Microsoft.Extensions.Caching.Redis
• Microsoft.AspNetCore.DataProtection.AzureStorage
• Microsoft.Extensions.Configuration.AzureKeyVault
• Microsoft.AspNetCore.DataProtection.AzureKeyVault
• Microsoft.AspNetCore.Identity.Service.AzureKeyVault
• Microsoft.AspNetCore.AzureKeyVault.HostingStartup
• Microsoft.AspNetCore.ApplicationInsights.HostingStartup

What’s in this build? Significant performance improvements were made, shared projects are now supported, code inspection severity can be configured, settings for our unit test runner can be edited, various updates to the NuGet tool window UI, and more. Check out the list of fixes in this build if you feel like digging into details. 

We are excited to announce the release of Windows Package Manager 1.0! 

Simple mediator implementation in .NET. In-process messaging with no dependencies.
Supports request/response, commands, queries, notifications and events, synchronous and async with intelligent dispatching via C# generic variance.

You should install MediatR with NuGet:

 Install-Package MediatR 

Or via the .NET Core command line interface:

 dotnet add package MediatR 

- Added `Select *` plugin.
- Added `Duplicate Commands Per Context` plugin.
- Updated ByMethods plugin to show stack traces of commands.
- Added ability of closing/hiding different tabs.
- Added assembly info to methods info view.
- Updated the NuGet Packages
PM> Update-Package DNTProfiler.EntityFramework.Core
Or
PM> Update-Package DNTProfiler.NHibernate.Core 

PM> update-package

PM> update-package -reinstall