DEV Community: 1001binary

How to get ScrollViewer from ListView in UWP?

1001binary — Fri, 12 Nov 2021 14:12:31 +0000

Basically, the ScrollViewer is built-in to ListView. Suppose you developed a desktop application based on UWP. In this application, there's one page containing StudentListView. One day you want to scroll it to its top. A first question will be asked that: how to get ScrollViewer from ListView? The following code will answer this question:

XAML

<ListView x:Name="StudentListView"></ListView>

Code Behind

Border border = VisualTreeHelper.GetChild(StudentListView, 0)
as Border;
ScrollViewer scrollViewer = VisualTreeHelper.GetChild(border, 0)
as ScrollViewer;

Next, you can use the following code to scroll StudentListView to its top:

if (scrollViewer != null) {
   scrollViewer.ChangeView(0, 0, 1);
}

Hope this post would be useful for you.

Happy coding :)

Integrate your website into Cloudflare

1001binary — Fri, 16 Apr 2021 10:09:55 +0000

Suppose you have hosted your website. One day you want it more secured, DDos mitigation and faster. Don't worry! Cloudflare can help you. Cloudflare provides services such as CDN, DDos mitigation, internet security and so on. Cloudflare sits between users and your hosting server. This means that Cloudflare will handle requests from clients before going to web server. Cloudflare offers free and paid packages. This depends on your needs.

The following is steps by steps to integrate your website into Cloudflare:

Register a new account at Cloudflare.
https://dash.cloudflare.com/sign-up
Sign in Cloudflare.
https://dash.cloudflare.com/login
Replace your DNS provider's nameservers into Cloudflare-Nameservers.

Name	Server
NS	[YOUR_CLOUDFLARE_NAMESERVER1]
NS	[YOUR_CLOUDFLARE_NAMESERVER2]

Click "Add Website" link on Cloudflare website.
Enter your domain.
Go to DNS area to add following DNS records:

DNS Type	Name	Value
A	www	[IP_ADDRESS_OF_YOUR_SERVER]

Make a cup of tea.
Your website is live.

Cloudflare's Benefits:

Users can't see actual IP Address of your server over Browser Development Tools.
Assets of your website will be automatically cached such as JavaScript files, Stylesheets and so on.
Always redirect http to https.
...

Hope you enjoy this post.

Happy coding :)

Insert center image in README.md on Github

1001binary — Fri, 16 Apr 2021 08:58:49 +0000

Github is popular. As far as I see, most of developers know it quite well. They create projects, contribute code, write instructions in README.md and so on.

In README.md, one day you want to insert center image into it. You don't know somehow to do it using Markdown. Fortunatelly, Markdown on Github supports some HTML tags. Two of them are p and img.

The following is the way to insert center image into README.md:

<p align="center">
   <img src="[YOUR_RAW_IMAGE_URL]" alt="[YOUR_ALT]"/>
</p>

It's cool, right?

Hope you enjoy this post.

Happy coding :)

Download file using HttpClient wrapper asynchronously.

1001binary — Fri, 16 Apr 2021 08:46:10 +0000

HttpClient is a simple and robust wrapper to send and receive HTTP requests. It's an awesome alternative to the legacy HTTP client .NET api. I like HttpClient the best. It's free, efficient and especially easy to use. You can send HTTP requests and then receive data back only with a couple of code lines.

For instance:
A function to download file with a provided uri and output path.

public static class HttpHelper
{
   private static readonly HttpClient _httpClient = new HttpClient();

   public static async void DownloadFileAsync(string uri
        , string outputPath)
   {
      Uri uriResult;

      if (!Uri.TryCreate(uri, UriKind.Absolute, out uriResult))
         throw new InvalidOperationException("URI is invalid.");

      if (!File.Exists(outputPath))
         throw new FileNotFoundException("File not found."
            , nameof(outputPath));

      byte[] fileBytes = await _httpClient.GetByteArrayAsync(uri);
      File.WriteAllBytes(outputPath, fileBytes);
   }
}

Hope you enjoy this post.

Happy coding :)

Implement Repository Base and Unit of Work in C#

1001binary — Thu, 15 Apr 2021 14:10:52 +0000

Introduction and Implementation

The repository pattern belongs to the family of design patterns. It's used for handling common data access. It's easily maintainable and highly testable. Besides that, Unit Of Work can be seen as transaction to ensure that all operations in an unit are successfully executed. If one of them is failed, nothing happens.

In C#, there is an interface called IQueryable. It is like lazy interface. When called, it will be executed. This interface fits to Repository pattern well.

First, we define a new class EntityBase with Id and Version.

public class EntityBase
{
   public int Id { get; set; }
   public byte[] Version { get; set; }
}

The Version property can help to check concurrency in database. Nowadays, most of ORMs support concurrency check automatically.

Second, we define a new interface IRepository where its constraint of T is EntityBase. There, we will write 5 methods: List, Create, Read, Update and Delete. This can call LCRUD.

public interface IRepository<T> where T: EntityBase
{
   IQueryable<T> List();
   void Create(T entity);
   T Read(object keys);
   void Update(T entity);
   void Delete(T entity);
}

Third, we implement a new class GenericRepository using DbContext in Entity Framework.

public abstract class GenericRepository<T> : IRepository<T>
    where T: EntityBase
{
   private readonly DbContext _dbContext;

   public GenericRepository(DbContext dbContext)
   {
      this._dbContext = dbContext;
   }

   public virtual IQueryable<T> List()
   {
      return _dbContext.Set<T>();
   }

   public virtual void Create(T entity)
   {
      _dbContext.Set<T>().Add(entity);
   }

   public virtual T Read(object keys)
   {
      return _dbContext.Set<T>().Find(keys);
   }

   public virtual void Update(T entity)
   {
      _dbContext.Entry(entity).State = EntityState.Modified;
   }

   public virtual void Delete(T entity)
   {
      _dbContext.Set<T>().Remove(entity);
   }
}

Lastly, we create a new class UnitOfWork.

public sealed class UnitOfWork : IDisposable
{
   private readonly DbContext _dbContext;

   public UnitOfWork(DbContext dbContext)
   {
      this._dbContext = dbContext;
      // TODO: Initialize repositories here...
      // e.g. this.StudentRepository
                  // = new StudentRepository(dbContext);
   }

   public bool Save()
   {
      bool isSuccess = _dbContext.SaveChanges() > 0;
      return isSuccess;
   }

   public void Dispose()
   {
      if (_dbContext == null) return;
      _dbContext.Dispose();
   }

   // e.g. public readonly IStudentRepository StudentRepository;
}

Usage

Each entity must inherit EntityBase.
For each entity, you must create a new interface I[xxx]Repository and a new class [xxx]Repository inheriting GenericRepository and implementing I[xxx]Repository.
New Repository classes have to be initialized in UnitOfWork class.

Best Practices:

We can take advantage of IoC frameworks to register DbContext and UnitOfWork into services container and then use UnitOfWork as constructor parameter.

Samples

Suppose StudentDbContext is provided and Ninject is used for registering two services UnitOfWork and StudentDbContext. UnitOfWork will be automatically injected in Studentcontroller.

public class StudentController : ControllerBase
{
   private readonly UnitOfWork _unitOfWork;

   public StudentController(UnitOfWork unitOfWork)
   {
      this._unitOfWork = unitOfWork;
   }
}

A Console application is to add two new Students to database.

public class Program
{
   static void Main(params string [] args)
   {
      DbContext studentDbContext = new StudentDbContext();
      using(UnitOfWork unitOfWork = new UnitOfWork(studentDbContext))
      {
         unitOfWork.StudentRepository
             .Create(new Student("Larry", "Page"))
         unitOfWork.StudentRepository
             .Create(new Student("Mark", "Zuckerberg"))
         unitOfWork.Save();
      }

   }
}

Hopefully, this post can help you to implement your own repository and unit of work.

Happy coding :)

Protect class from disallowing changes to values outside in C#

1001binary — Thu, 15 Apr 2021 13:02:30 +0000

The nature of OOP is to make program which are organized better into classes rather than functional programming. One of them is the class protection from disallowing any changes to values outside, once they are set. When writing code in OOP, it's significant to preserve its integrity.

The following is a small sample in C#:

Demo

public class Student
{
   public string FirstName { get; set; }
   public string LastName { get; set; }
}

Fair enough :)

Production

The above code should be:

public class Student
{
   public Student(string firstName, string lastName)
   {
      this.FirstName = firstName;
      this.LastName = lastName;
   }
   public readonly string FirstName;
   public readonly string LastName;
}

This disallows any changes to FirstName and LastName outside.

Hope you enjoy this post.

Happy coding :)

Insert Github Stats into Your Profile's README.

1001binary — Fri, 09 Apr 2021 16:35:33 +0000

This is C# code to demonstrate how to insert Github Stats into your profile's README.

// First of all, sign in Github on the default browser.

const string yourGithubUsername = "YOUR_GITHUB_USERNAME";

// Go to README of your Github profile.
Process.Start($"https://github.com/{yourGithubUsername}
                /{yourGithubUsername}/edit/master/README.md");

// Insert this into README file and then replace YOUR_NAME
// and YOUR_GITHUB_USERNAME.
/*
[[YOUR_NAME]'s Stats](https://github-readme-stats.vercel.app
/api?username=[YOUR_GITHUB_USERNAME]&show_icons=true)
*/

// Sleep 15 seconds.
Thread.Sleep(TimeSpan.FromSeconds(15))
Console.WriteLine("Done")

It sounds interesting, right?

Happy coding :)

How to fix Static Files not working in ASP.NET Core

1001binary — Fri, 09 Apr 2021 12:11:25 +0000

One day I have been working on a project using ASP.NET Core. I have experienced a problem serving static files such as index.html in ASP.NET Core. Basically, I thought that ASP.NET core package included handling and configuring static files.

Finally, I ended up installing a separate package Microsoft.AspNetCore.StaticFiles to get it worked.

Hope you enjoy this post.

Happy coding :)

Update UI state from an another Thread in Windows Forms

1001binary — Fri, 09 Apr 2021 12:03:30 +0000

An exception is thrown when trying to update control state from an another Thread.

Thread newThread = new Thread(new ThreadDelegate(() => {
   txtStatus.Text = "Started";
}));

newThread.Start();

Solution

We use BeginInvoke to update UI state asynchronously.

Thread newThread = new Thread(new ThreadDelegate(() => {
   txtStatus.BeginInvoke(() =>
   {
       txtStatus.Text = "Started";
   });
}));

newThread.Start();

Happy coding!

Introduction to Kecomaac

1001binary — Fri, 09 Apr 2021 11:31:39 +0000

In this post, I would like to introduce you a Windows desktop application keeping your computer always active. It's called Kecomaac. Its name is abbreviation of KEep COMputer Always ACtive.

Why using Kecomaac?

To know further why we should use Kecomaac, now let's analyze two possible scenarios:

Scenario 1

Suppose you have been working on Microsoft Teams. One day you want to keep it always online without away status after minutes.

Scenario 2

Assume you will go away about some minutes to do something, but you still wanna keep your Skype online without away status.

Basically, Microsoft Teams or Skype or others will mark your status as away if there is no any interaction after minutes.

To keep your computer always active, you will have to cheat OS by simulating constant mouse movement automatically.

That's why Kecomaac was born to solve this problem.

Supported Platforms

Kecomaac is an open source application written in Windows Forms + .NET Framework 2.0. Therefore, it can run on Windows XP and higher.

Kecomaac supports Portable version and Installer version.

You can find entire source code of Kecomaac and download it at the following link:

https://github.com/1001binary/Kecomaac

Any your idea about Kecomaac will be appreciated.

I always welcome any idea.

Hope you enjoy Kecomaac!

Integrate Ninject into ASP.NET MVC 5 and Web API.

1001binary — Mon, 22 Feb 2021 15:10:28 +0000

In this post, I show you how to integrate Ninject into ASP.NET MVC and Web API.

Prior to the implementation, I explain to you what Ninject is. Ninject is a IoC framework for .NET platform to help you to integrate DI into .NET applications easily.

Install Nuget Packages

Ninject.Web.WebApi
Ninject.MVC5

Implement the integration

Integrating Ninject is simple:

Global.asax must inherit NinjectHttpApplication
Override the CreateKernel method.
Inject required services.

Public Class Global_asax
    Inherits NinjectHttpApplication

    Protected Overrides Function CreateKernel() As IKernel
        Dim kernel = New StandardKernel()
        RegisterServices(kernel)
        Return kernel
    End Function

    Private Sub RegisterServices(ByVal kernel As IKernel)
        ' TODO: inject your services here...
        ' e.g. kernel.Bind(Of IUserAccountRepository)().To(Of UserAccountRepository).InRequestScope()
    End Sub

    Protected Overrides Sub OnApplicationStarted()
        MyBase.OnApplicationStarted()
        AreaRegistration.RegisterAllAreas()
        GlobalConfiguration.Configure(AddressOf WebApiConfig.Register)
        RouteConfig.RegisterRoutes(RouteTable.Routes)
    End Sub

End Class

ASP.NET MVC

Public Class HomeController
    Inherits Controller

    Private ReadOnly UserRepository As IUserAccountRepository

    Public Sub New(UserRepository As IUserAccountRepository)
        Me.UserRepository = UserRepository
    End Sub

End Class

ASP.NET Web API

Public Class UserApiController
    Inherits ApiController

    Private ReadOnly UserRepository As IUserAccountRepository

    Public Sub New(UserRepository As IUserAccountRepository)
        Me.UserRepository = UserRepository
    End Sub

End Class

Hope you enjoy this post

Happy coding :)

Hashing Password combining with Salt in C# and VB.NET

1001binary — Mon, 22 Feb 2021 14:47:08 +0000

In this post, I show you how to protect password using hash-salt mechanism.

Hashing password using salt is one of the best practices in protecting user accounts from hackers and who you don't want anyone to see plain-text passwords in databases or text files. This is really great. In case hackers have stolen databases, they also need more time to decryte them. It won't be easy at all. At the same time, you have time to reset all passwords or suggest users to change passwords right away.

My background is .NET developer. That's why I have written two simple functions in C# and VB.NET as below.

public class SecurityHelper
{
    public static string GenerateSalt(int nSalt)
    {
        var saltBytes = new byte[nSalt];

        using (var provider = new RNGCryptoServiceProvider())
        {
            provider.GetNonZeroBytes(saltBytes);
        }

        return Convert.ToBase64String(saltBytes);
    }

    public static string HashPassword(string password, string salt, int nIterations, int nHash)
    {
        var saltBytes = Convert.FromBase64String(salt);

        using (var rfc2898DeriveBytes = new Rfc2898DeriveBytes(password, saltBytes, nIterations))
        {
            return Convert.ToBase64String(rfc2898DeriveBytes.GetBytes(nHash));
        }
    }
}

VB.NET

Public Class SecurityHelper
    Public Shared Function GenerateSalt(ByVal nSalt As Integer) As String
        Dim saltBytes = New Byte(nSalt) {}

        Using provider = New RNGCryptoServiceProvider()
            provider.GetNonZeroBytes(saltBytes)
        End Using

        Return Convert.ToBase64String(saltBytes)
    End Function

    Public Shared Function HashPassword(ByVal password As String, ByVal salt As String, ByVal nIterations As Integer, ByVal nHash As Integer) As String
        Dim saltBytes = Convert.FromBase64String(salt)

        Using rfc2898DeriveBytes = New Rfc2898DeriveBytes(password, saltBytes, nIterations)
            Return Convert.ToBase64String(rfc2898DeriveBytes.GetBytes(nHash))
        End Using
    End Function
End Class

For example:

string pwd = "123Abc#@";
string salt = SecurityHelper.GenerateSalt(70);
string pwdHashed = SecurityHelper.HashPassword(pwd, salt, 10101, 70);
Console.WriteLine(pwdHashed);
Console.WriteLine(salt);

Hope you enjoy this post.

Happy coding :)