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European ASP.NET Core Hosting :: Knowing about WinForms and .NET Core 3.0

clock October 11, 2019 09:29 by author Scott

Desktop support for .NET Core 3.0 has been in preview for some time, it is slated to be released later this year. As per indicators by Microsoft, .NET Core will receive more updates compared to full .NET Framework, keeping this in mind, it makes sense to start thinking about migrating existing applications and creating new ones on .NET Core if the application still has some years to go.

Desktop support in .NET Core has not been completely migrated yet; however, it is possible to create and migrate WinForms applications using the preview bits. In this article, we'll consider the creation and migration of a WinForms application in .NET Core 3.0 that uses ComponentOne controls.

Creating a New .NET Core 3.0 Application

To create a new .NET Core 3.0 application, it's recommended to download VS 2019 and the nightly build of the .NET Core 3.0 SDK. Make sure that you’ve installed the .NET Framework 4.7.2 and .NET Core 2.1 development tools in the Visual Studio Installer. This software will be necessary whether you plan on creating a new project or migrating an existing one to .NET Core 3.0.

The simplest way to work with .NET Core 3.0 (for now) is to use dotnet.exe command line utility. It can be used to create a new project, add/restore dependencies, build, etc.

.NET Core 3 - Using x64 and x86 Versions

Visual Studio uses the appropriate version depending on your .NET Core 3 project’s target platform – x86 or x64. It uses last installed version for both platforms. So, if you intend to build your project for both platforms, you must download and install both platform SDK versions with the same version.

These are the typical paths for .NET Core 3 command line utility:

  • c:\Program Files\dotnet\dotnet.exe - for x64 version of .Net Core 3
  • c:\Program Files (x86)\dotnet\dotnet.exe- for x86 version of .Net Core 3

Let’s use x64 version of dotnet.exe to simplify it for further description.

Create a New Visual Studio Project

First, you’ll need to open the Visual Studio Developer Command Prompt to create a project through the command line. Currently, the tooling for Visual Studio is very limited in its support of .NET Core 3.0, so it’s easiest to create a project through the command line interface.

First, we’ll create the project:

“c:\Program Files\dotnet\dotnet.exe” **new** winforms -o TestAppWinFormsCore

Once this is finished, we’ll navigate into the project directory:

cd TestAppWinFormsCore

Finally, we can run the project to make sure that it works:

“c:\Program Files\dotnet\dotnet.exe” run

Now that the project has been created, we can use Visual Studio 2019 to open it and modify its contents. 

In the Visual Studio 2019, open the TestAppWinFormsCore.csproj file we just created.

You should see something like this in Visual Studio:

.NET Core 3.0 uses a new project type and has no design-time support currently, so the process of adding controls will be a little different than what you may be accustomed to. We need to add C1 libraries manually to the project to make use of them, also, we should add the controls manually to Form1.cs because of missing design-time support.

Because of this, let’s use a trick. We'll add the classic .NET Framework WinForms project in order to use its Form designer:

1. Right-click on Solution node and Add – New Project… - Windows Forms Desktop project (with .Net Framework, say version 4.0). The name of new project is by default WindowsFormsApp1.

2. Remove the existing Form1 from WindowsFormsApp1 project

3. Add Form1.cs from TestAppWinFoirmsCore project as link:

After that, the following view of Solution Explorer appears:

Now, we can edit Form1 form in the usual way:

Now, remove unneeded “Hello .NET Core!” label and add some C1 control, for example C1DockingTab:

Launch WindowsFormsApp1 application and observe C1DockingTab on Form1. But this will be a .Net Framework 4 application.

Adding C1DockingTab caused adding C1.Win.C1Command.4 reference to WindowsFormsApp1 project. Therefore, the same reference should be added to TestAppWinFormsCore project also. For this let’s take a look in the properties of the C1.Win.C1Command.4 reference (right-click – Properties…) and find the path to the assembly. It looks like C:\Program Files (x86)\ComponentOne\WinForms Edition\bin\v4.0\C1.Win.C1Command.4.dll. Add this reference to the TestAppWinFormsCore project (right-click on Dependencies – Add reference… - Browse… - choose C:\Program Files (x86)\ComponentOne\WinForms Edition\bin\v4.0\C1.Win.C1Command.4.dll).

You should be able to run the code at this point, though you’ll notice a ComponentOne nag screen since the TestAppWinFormsCore project doesn’t contain any licensing information.

We can correct this by adding a licenses.licx file to the project. To do so, right-click on TestAppWinFormsCore project and select Add -> Existing Items. And browse the licenses.licx file from WindowsFormsApp1/Properties folder.

Build and rerun the app and you should no longer see a nag screen.

And now this is a genuine .NET Core 3.0 WinForms app. You can see this in the Modules window. All system references are from C:\Program Files\dotnet... folder.

Migrating an Existing Project to .NET Core 3.0

It is possible to migrate an existing project to .NET Core 3.0, though the process may require a few more steps than you would expect. Also, before trying to migrate a project, it’s worth running Microsoft’s portability analyzer tool on the project you want to convert.

The tool can give you an idea (ahead of time) how compatible your project will be with .NET Core 3.0, and it points out potential problems you may run into (included unsupported APIs).

If you’ve made up your mind to try to migrate a project, it’s easiest to begin the process by creating a project through dotnet.exe as described above.Let’s look at the WeatherChart sample migration. This sample demonstrates the C1FlexChart control possibilities.

First, we’ll create a new DotNetCore3FlexChart project from the command line:

“c:\Program Files\dotnet\dotnet.exe” **new** winforms -o DotNetCore3FlexChart

Once this is finished, we’ll navigate into the project directory and open DotNetCore3FlexChart.csproj from Visual Studio 2019.

Next, add the WeatherChart project to the DotNetCore3FlexChart solution. WeatherChart project is placed in Documents\ComponentOne Samples\WinForms\C1FlexChart\CS\WeatherChart\WeatherChart\WeatherChart.csproj by default.

Here, we'll use the WeatherChart project in our .NET Core 3.0 project. Therefore, the WeatherChart project reference should be added to DotNetCore3FlexChart dependencies (right-click on Dependencies – Add Reference… - Projects - WeatherChart)

After that, open Project.cs from DotNetCore3FlexChart project and change the following line:

Application.Run(new Form1()); 

by 

Application.Run(new WeatherChart.Form1()); 

It means that the .NET Core 3.0 app (DotNetCore3FlexChart) will run WeatherChart.Form1 from WeatherChart assembly instead of own Form1\.

That’s all!

If you run the WeatherChart project it will be launched as .NET Framework 4.0 app.

But if you run the DotNetCore3FlexChart project then the WeatherChart assembly will be launched in .NET Core 3.0 environment.

.NET Core 3.0 Preview Caveats

Using the .NET Core 3.0 Preview for any kind of day-to-day work isn’t recommended at this point, as it’s obviously still work in progress. As the steps above illustrate, much of the project creation and migration processes require a lot of manual configuration from the user, and it’s possible to find some bugs and unfinished implementations presently.The lack of designer support also makes working with the preview somewhat difficult, though Microsoft has committed to adding this feature in the coming months.

Overall, .NET Core 3.0 will be an important change for developers, though this preview is merely the first step.



European ASP.NET Core 3 Hosting :: ASP.NET Core 3 Certificate Authentication

clock October 8, 2019 12:04 by author Scott

This article shows how Certificate Authentication can be implemented in ASP.NET Core 3.0. In this example, a shared self signed certificate is used to authenticate one application calling an API on a second ASP.NET Core application.

Setting up the Server

Add the Certificate Authentication using the Microsoft.AspNetCore.Authentication.Certificate NuGet package to the server ASP.NET Core application.

 

This can also be added directly in the csproj file.

<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <AspNetCoreHostingModel>OutOfProcess</AspNetCoreHostingModel>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.Authentication.Certificate"
      Version="3.0.0-preview6.19307.2" />
  </ItemGroup>

  <ItemGroup>
    <None Update="sts_dev_cert.pfx">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>

</Project>

The authentication can be added in the ConfigureServices method in the Startup class. This example was built using the ASP.NET Core documentation. The AddAuthentication extension method is used to define the default scheme as “Certificate” using the CertificateAuthenticationDefaults.AuthenticationScheme string. The AddCertificate method then adds the configuration for the certificate authentication. At present, all certificates are excepted which is not good and the MyCertificateValidationService class is used to do extra validation of the client certificate. If the validation fails, the request is failed and the request for the resource will be rejected.

public void ConfigureServices(IServiceCollection services)
{
    services.AddSingleton<MyCertificateValidationService>(); 

    services.AddAuthentication(CertificateAuthenticationDefaults.AuthenticationScheme)
        .AddCertificate(options => // code from ASP.NET Core sample
        {
            options.AllowedCertificateTypes = CertificateTypes.All;
            options.Events = new CertificateAuthenticationEvents
            {
                OnCertificateValidated = context =>
                {
                    var validationService =
                        context.HttpContext.RequestServices.GetService<MyCertificateValidationService>(); 
                    if (validationService.ValidateCertificate(context.ClientCertificate))
                    {
                        var claims = new[]
                        {
                            new Claim(ClaimTypes.NameIdentifier, context.ClientCertificate.Subject, ClaimValueTypes.String, context.Options.ClaimsIssuer),
                            new Claim(ClaimTypes.Name, context.ClientCertificate.Subject, ClaimValueTypes.String, context.Options.ClaimsIssuer)
                        }; 

                        context.Principal = new ClaimsPrincipal(new ClaimsIdentity(claims, context.Scheme.Name));
                        context.Success();
                    }
                    else
                    {
                        context.Fail("invalid cert");
                    } 

                    return Task.CompletedTask;
                }
            };
        }); 

    services.AddAuthorization(); 

    services.AddControllers();
}

The AddCertificateForwarding method is used so that the client header can be specified and how the certificate is to be loaded using the HeaderConverter option. When sending the certificate with the HttpClient using the default settings, the ClientCertificate was always be null. The X-ARR-ClientCert header is used to pass the client certificate, and the cert is passed as a string to work around this.

services.AddCertificateForwarding(options =>
{
    options.CertificateHeader = "X-ARR-ClientCert";
    options.HeaderConverter = (headerValue) =>
    {
        X509Certificate2 clientCertificate = null;
        if(!string.IsNullOrWhiteSpace(headerValue))
        {
            byte[] bytes = StringToByteArray(headerValue);
            clientCertificate = new X509Certificate2(bytes);
        }

        return clientCertificate;
    };
});

The Configure method then adds the middleware. UseCertificateForwarding is added before the UseAuthentication and the UseAuthorization.

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    ...     
    app.UseRouting(); 

    app.UseCertificateForwarding();
    app.UseAuthentication();
    app.UseAuthorization(); 

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });
}

The MyCertificateValidationService is used to implement validation logic. Because we are using self signed certificates, we need to ensure that only our certificate can be used. We validate that the thumbprints of the client certificate and also the server one match, otherwise any certificate can be used and will be be enough to authenticate.

using System.IO;
using System.Security.Cryptography.X509Certificates; 

namespace AspNetCoreCertificateAuthApi
{
    public class MyCertificateValidationService
    {
        public bool ValidateCertificate(X509Certificate2 clientCertificate)
        {
            var cert = new X509Certificate2(Path.Combine("sts_dev_cert.pfx"), "1234");
            if (clientCertificate.Thumbprint == cert.Thumbprint)
            {
                return true;
            } 

            return false;
        }
    }
}

The API ValuesController is then secured using the Authorize attribute.

[Route("api/[controller]")]
[ApiController]
[Authorize]
public class ValuesController : ControllerBase


...

The ASP.NET Core server project is deployed in this example as an out of process application using kestrel. To use the service, a certificate is required. This is defined using the ClientCertificateMode.RequireCertificate option.

public static IWebHost BuildWebHost(string[] args)
  => WebHost.CreateDefaultBuilder(args)
  .UseStartup<Startup>()
  .ConfigureKestrel(options =>
  {
    var cert = new X509Certificate2(Path.Combine("sts_dev_cert.pfx"), "1234");
    options.ConfigureHttpsDefaults(o =>
    {
        o.ServerCertificate = cert;
        o.ClientCertificateMode = ClientCertificateMode.RequireCertificate;
    });
  })
  .Build();

Implementing the HttpClient

The client of the API uses a HttpClient which was create using an instance of the IHttpClientFactory. This does not provide a way to define a handler for the HttpClient and so we use a HttpRequestMessage to add the Certificate to the “X-ARR-ClientCert” request header. The cert is added as a string using the GetRawCertDataString method.

private async Task<JArray> GetApiDataAsync()
{
    try
    {
        var cert = new X509Certificate2(Path.Combine(_environment.ContentRootPath, "sts_dev_cert.pfx"), "1234"); 

        var client = _clientFactory.CreateClient(); 

        var request = new HttpRequestMessage()
        {
            RequestUri = new Uri("
https://localhost:44379/api/values"),
            Method = HttpMethod.Get,
        }; 

        request.Headers.Add("X-ARR-ClientCert", cert.GetRawCertDataString());
        var response = await client.SendAsync(request); 

        if (response.IsSuccessStatusCode)
        {
            var responseContent = await response.Content.ReadAsStringAsync();
            var data = JArray.Parse(responseContent); 

            return data;
        } 

        throw new ApplicationException($"Status code: {response.StatusCode}, Error: {response.ReasonPhrase}");
    }
    catch (Exception e)
    {
        throw new ApplicationException($"Exception {e}");
    }
}

If the correct certificate is sent to the server, the data will be returned. If no certificate is sent, or the wrong certificate, then a 403 will be returned. It would be nice if the IHttpClientFactory would have a way of defining a handler for the HttpClient. I also believe a non valid certificates should fail per default and not require extra validation for this. The AddCertificateForwarding should also not be required to use for a default HTTPClient client calling the service.

Certificate Authentication is great, and helps add another security layer which can be used together with other solutions. See the code and ASP.NET Core src code for further documentation and examples. Links underneath. 



European ASP.NET Core Hosting :: File Upload in Angular 7

clock September 20, 2019 10:52 by author Scott

In this article, we will see how to upload a file into the database using the Angular 7 app in an ASP.NET project. Let us create a new project in Visual Studio 2017. We are using ASP.NET Core 2 and Angular 7 for this project.

Prerequisites:

  • Node JS must be installed
  • Angular CLI must be installed
  • Basic knowledge of Angular

Let’s get started.

Create a new project and name it as FileUploadInAngular7

Select a new project with Angular in .NET Core and uncheck the configure HTTPS

Your project will be created. Left click on ClientApp and open it in file explorer

Type cmd as shown in the picture.

Type npm install in the cmd

Now it will take time and all the node_modules will be installed in the project.

Create a Web API controller as UploadController.

Add the following code in it.

using System.IO;
using System.Net.Http.Headers;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
namespace FileUploadInAngular7.Controllers
{
    [Produces("application/json")]
    [Route("api/[controller]")]
    public class UploadController : Controller
    {
        private IHostingEnvironment _hostingEnvironment;
        public UploadController(IHostingEnvironment hostingEnvironment)
        {
            _hostingEnvironment = hostingEnvironment;
        }
        [HttpPost, DisableRequestSizeLimit]
        public ActionResult UploadFile()
        {
            try
            {
                var file = Request.Form.Files[0];
                string folderName = "Upload";
                string webRootPath = _hostingEnvironment.WebRootPath;
                string newPath = Path.Combine(webRootPath, folderName);
                if (!Directory.Exists(newPath))
                {
                    Directory.CreateDirectory(newPath);
                }
                if (file.Length > 0)
                {
                    string fileName = ContentDispositionHeaderValue.Parse(file.ContentDisposition).FileName.Trim('"');
                    string fullPath = Path.Combine(newPath, fileName);
                    using (var stream = new FileStream(fullPath, FileMode.Create))
                    {
                        file.CopyTo(stream);
                    }
                }
                return Json("Upload Successful.");
            }
            catch (System.Exception ex)
            {
                return Json("Upload Failed: " + ex.Message);
            }
        }
    }
}

Navigate to the following path and open both the files.

In home.component.html write the following code.

<h1>File Upload Using Angular 7 and ASP.NET Core Web API</h1>
<input #file type="file" multiple (change)="upload(file.files)" />
<br />
<span style="font-weight:bold;color:green;" *ngIf="progress > 0 && progress < 100">
  {{progress}}%
</span>
<span style="font-weight:bold;color:green;" *ngIf="message">
  {{message}}
</span>

In home.component.ts file write the following code in it.

import { Component, OnInit } from '@angular/core';
import { HttpClient, HttpRequest, HttpEventType, HttpResponse } from '@angular/common/http';
@Component({
  selector: 'app-home',
  templateUrl: './home.component.html',
})
export class HomeComponent {
  public progress: number;
  public message: string;
  constructor(private http: HttpClient) { }
  upload(files) {
    if (files.length === 0)
      return;
    const formData = new FormData();
    for (let file of files)
      formData.append(file.name, file);
    const uploadReq = new HttpRequest('POST', `api/upload`, formData, {
      reportProgress: true,
    });
    this.http.request(uploadReq).subscribe(event => {
      if (event.type === HttpEventType.UploadProgress)
        this.progress = Math.round(100 * event.loaded / event.total);
      else if (event.type === HttpEventType.Response)
        this.message = event.body.toString();
    });
  }
}

Run the project and you will see the following output.



ASP.NET 4.8 Hosting - HostForLIFE.eu :: Display SiteMap Links On ASP.NET Page

clock September 17, 2019 12:33 by author Peter

Create a sitemap sml based file and save it with sitemap.config name. Here is an example.
    <?xml version="1.0" encoding="utf-8" ?> 
    <siteMap> 
    <siteMapNode title="Home" controller="Home" action="Overview"> 
    <siteMapNode title="Dashboard" nopResource="Admin.Dashboard" controller="Home" action="Index" ImageUrl="~/Administration/Content/images/ico-dashboard.png" /> 
    <siteMapNode title="Catalog" nopResource="Admin.Catalog" PermissionNames="ManageCatalog" ImageUrl="~/Administration/Content/images/ico-catalog.png" > 
    <siteMapNode title="Categories" nopResource="Admin.Catalog.Categories"> 
    <siteMapNode title="List" nopResource="Admin.Common.List" controller="Category" action="List"/> 
    <siteMapNode title="Tree view" nopResource="Admin.Common.Treeview" controller="Category" action="Tree"/> 
    </siteMapNode> 
    </siteMap> 


If you're new to sitemap, learn here how to create a site map in Visual Studio.
 
To bind above sitemap and display on a page, please follow the below code example.
    @using System.Data; 
    @using System; 
    <div class="page-title"> 
    <h2>"Sitemap"</h2> 
    </div> 
    @{ 
    string fileName = System.Web.HttpContext.Current.Server.MapPath("~/sitemap.config"); 
    DataSet ds = new DataSet(); 
    ds.ReadXml(fileName); 
    <table> 
    <tr> 
    <td width="20%"></td> 
    <td style="border: 2px double #CCCCCC; padding-left: 50px;" width="30%"> 
    @for(int i=1;i<ds.Tables[0].Rows.Count/2;i++) 
    { 
    if(ds.Tables[0].Rows[i]["action"].ToString()=="") 
    { 
    <h4>@ds.Tables[0].Rows[i]["title"].ToString()</h4> 
    } 
    else 
    { 
    string url = "../" + @ds.Tables[0].Rows[i]["controller"].ToString() + "/" + @ds.Tables[0].Rows[i]["action"].ToString(); 
    <ul class="top-menu"><li><a href="@url" temp_href="@url">@ds.Tables[0].Rows[i]["title"].ToString()</a></li></ul> 
    } 
    } 
    </td> 
    <td style="border: 2px double #CCCCCC; padding-left: 50px;" width="30%"> 
    @for (int i = ds.Tables[0].Rows.Count / 2; i < ds.Tables[0].Rows.Count; i++) 
    { 
    if(ds.Tables[0].Rows[i]["action"].ToString()=="") 
    { 
    <h4>@ds.Tables[0].Rows[i]["title"].ToString()</h4> 
    } 
    else 
    { 
    string url = "../" + @ds.Tables[0].Rows[i]["controller"].ToString() + "/" + @ds.Tables[0].Rows[i]["action"].ToString(); 
    <ul class="top-menu"><li><a href="@url" temp_href="@url">@ds.Tables[0].Rows[i]["title"].ToString()</a></li></ul> 
    } 
    } 
    </td> 
    </tr> 
    </table> 
    } 


Run application and you'll see a page with sitemap links.

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European ASP.NET Core Hosting :: InProcess and OutOfProcess Hosting Model In ASP.NET Core

clock September 17, 2019 11:37 by author Scott

Once you finish developing an ASP.NET Core web application, you need to deploy it on a server so that end users can start using it. When it comes to deployment to IIS, ASP.NET Core offers two hosting models namely InProcess and OutOfProcess. In this article you learn about these hosting models and how to configure them.

When you deploy your web application to IIS, various requests to the application are handled by what is known as ASP.NET Core Module. Under default settings the hosting model for your application is InProcess. This means ASP.NET Core Module forwards the requests to IIS HTTP Server (IISHttpServer). The IIS HTTP Server is a server that runs in-process with IIS. This results in great performance as compared to Out Of Process model. In-process models bypasses built-in Kestrel web server of ASP.NET Core.

If you decide to use Out-Of-Process hosting model then IIS HTTP Server won't be used. Instead Kestrel web server is used to process your requests. So, ASP.NET Core Module forwards your requests to Kestrel web server. This communication is out-of-process communication and is therefore slower than the in-process model.

Now that you have some basic idea about the in-process and out-of-process hosting models let's see how to configure them.

In order to understand the hosting models discussed in this article you first need to create an ASP.NET Core web application using Visual Studio. So, go ahead and do so based on any of the web application project templates. Make sure to use ASP.NET Core version 2.2 or later.

Once you create the project, click on the Build > Publish menu and Web Deploy the output (or manually copy to IIS) to IIS. Once you finish deploying the application locate the web.config file generated during the deployment process. In this web.config you will find a section like this:

<system.webServer>
  <handlers>
    <add name="aspNetCore" path="*" verb="*"
modules="AspNetCoreModuleV2" />
  </handlers>
  <aspNetCore processPath="dotnet"
              arguments=".\MyWebApp.dll"  
              stdoutLogEnabled="false"
              stdoutLogFile=".\logs\stdout"
              hostingModel="inprocess" />
</system.webServer>

As you can see the <aspNetCore> tag has hostingModel attribute that is set to inprocess by default.

Now, run the application from the browser with this default setting in place and observe the HTTP headers. The following figure shows one such sample run of the application.

As you can see the Server is Microsoft IIS.

Now, change the hostingModel attribute from inprocess to outofprocess. Run the application again. This time you will get the following output:

As you can see the Server is now Kestrel indicating that Out-Of-Process model is active.

In the preceding example you change the hosting model in the web.config generated during the publish operation. You can also specify the hosting model in project's .csproj file. Consider the following markup from .csproj file that does that.

<PropertyGroup>
    <TargetFramework>netcoreapp2.2</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
</PropertyGroup>

The <AspNetCoreHostingModel> element sets the hosting model to InProcess. To set it to Out-Of-Process you need to set it like this:

<AspNetCoreHostingModel>OutOfProcess</AspNetCoreHostingModel>

Run the application with these settings and confirm whether you get the outcome as before.

That's it for now! Keep coding!!



ASP.NET 4.8 Hosting - HostForLIFE.eu :: Use Distinct And FirstOrDefault Clauses In .NET Using linq.js

clock September 10, 2019 12:37 by author Peter

In this version, I will tell you about using Let us see how to use Distinct() and FirstOrDefault() clauses with the help of linq.js in .NET Web Application. It's useful to write simple LINQ queries from Entityframework to client side with LinqJS.

It’s better for validating data at the client side.
Improves performance of the application.

Let’s see one by one,
Distinct() function is different here.

C#.NET Code
    var FirstNameCollection = myDataArray.Select(x => x.FirstName).Distinct(); 
LinqJS Code
    // Retrieves non-duplicate FirstName values. 
    var FirstNameCollection = Enumerable.From(myDataArray).Distinct(function(x) { 
        return x.FirstName; 
    }).Select(function(FName) { 
        return FName; 
    }).ToArray(); 
The FirstOrDefault() function is nearly similar.

C#.NET Code
    public class cmbMonthOfWeek { 
        public string cmbMonth { 
            get; 
            set; 
        } 
        public int Id { 
            get; 
            set; 
        } 
    } 
    List < cmbMonthOfWeek > weekInfo = new List < cmbMonthOfWeek > (); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "First week", Id = 0 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Second week", Id = 1 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Third week", Id = 2 
    }); 
    weekInfo.Add(new cmbMonthOfWeek { 
        cmbMonth = "Fourth week", Id = 3 
    }); 
    var defaultWeekData = (from p in weekInfo where p.Id == 1 select p).FirstOrDefault();
Note

Here in defaultWeekData, you will get cmbMonth = "Second week".

LinqJS Code
    $scope.cmbMonthOfWeek = [{ 
        "cmbMonth": "First week", 
        "Id": 0 
    }, { 
        "cmbMonth": "Second week", 
        "Id": 1 
    }, { 
        "cmbMonth": "Third week", 
        "Id": 2 
    }, { 
        "cmbMonth": "Fourth week", 
        "Id": 3 
    }, ]; 
    var defaultWeekData = Enumerable.From($scope.cmbMonthOfWeek).Where(function(x) { 
        return x.Id == 1 
    }).FirstOrDefault();  Distinct And FirstOrDefault Clauses In .NET Using linq.js

HostForLIFE.eu ASP.NET 4.8 Hosting

European best, cheap and reliable ASP.NET hosting with instant activation. HostForLIFE.eu is #1 Recommended Windows and ASP.NET hosting in European Continent. With 99.99% Uptime Guaranteed of Relibility, Stability and Performace. HostForLIFE.eu security team is constantly monitoring the entire network for unusual behaviour. We deliver hosting solution including Shared hosting, Cloud hosting, Reseller hosting, Dedicated Servers, and IT as Service for companies of all size.



ASP.NET Hosting HostForLIFE.eu :: Centralized Exception Handling Without Using Try Catch Block In .Net Core 2.2 Web API

clock September 3, 2019 12:00 by author Peter

Rather than writing try catch block for each method, throwing exceptions manually and handling them, here we will use the power of .Net Core middleware to handle the exceptions at one single place, so that when an exception occurs anywhere in the code, the appropriate action can be taken. We will use UseExceptionHandler extension method that will add a middleware to the pipeline, and it will catch exceptions, log them, reset the request path, and re-execute the request if response has not already started.

Developer can customize the response format as well.

To achive this in .NetCore 2.2, this code snippet is very simple and it's just a matter of adding a few lines in your Startup.cs.

Simply go in Configure method and add the below code,
if (env.IsDevelopment()) {  
    app.UseDeveloperExceptionPage();  
} else {  
    app.UseExceptionHandler(errorApp => errorApp.Run(async context => {  
        // use Exception handler path feature to catch the exception details   
        var exceptionHandlerPathFeature = context.Features.Get < IExceptionHandlerPathFeature > ();  
        // log errors using above exceptionHandlerPathFeature object   
        Console.WriteLine(exceptionHandlerPathFeature ? .Error);  
        // Write a custom response message to API Users   
        context.Response.StatusCode = "500";  
        // Set a response format    
        context.Response.ContentType = "application/json";  
        await context.Response.WriteAsync("Some error occured.");  
    }));  
}  


The Console.WriteLine() is for demonstration purposes only. Here a developer can log the exceptions using any tool/package getting used in their project.

When any exceptions are thrown in the application this code will be executed and will produce the desired custom response in non-development environments (as in a development env we are using UseDeveloperExceptionPage() as a middleware).

HostForLIFE.eu ASP.NET 4.8 Hosting
HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes. We have customers from around the globe, spread across every continent. We serve the hosting needs of the business and professional, government and nonprofit, entertainment and personal use market segments.

 



ASP.NET 4.8 Hosting HostForLIFE.eu :: Fix Error on System.Web.UI.ViewStateException

clock August 27, 2019 12:38 by author Peter

In this post, I will tell you about fix System.Web.UI.ViewStateException: Invalid viewstate or System.Web.HttpException: The client disconnected exception Response.IsClientConnected Property ASP.NET 4.8.What is HttpResponse.IsClientConnected Property: HttpResponse.IsClientConnected used to gets a quality demonstrating whether the customer is still joined with the server.

The accompanying illustration utilizes the IsClientConnected property to check whether the customer that is asking for the page remains connected to the server. IfIsClientConnected is genuine, the code calls the  Redirect  technique, and the client will see an alternate page. In the event that IsClientConnected is false, then the code calls the End system and all page handling is ended.

 

And here is code that I used:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>Fix System.Web.UI.ViewStateException
    </title></head>
<body>
    <form id="form1" runat="server">
    <div>Welcome</div>
    </form>
</body>
</html>

C#
public partial class ClientDisconnected : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //Check whether the browser(client) remains connected to the server
        if (Response.IsClientConnected)
        {
            // if  browser connected, redirect to the Main.aspx page
            Response.Redirect("~/Main.aspx");
        }
        else
        {
            //if browser is not connected,terminate all response processing.
            Response.End();
        }
    }
}


VB.NET
Public Partial Class ClientDisconnected
    Inherits System.Web.UI.Page
    Protected Sub Page_Load(sender As Object, e As EventArgs)
        'Check whether the browser(client) remains connected to the server
        If Response.IsClientConnected Then
            ' if  browser connected, redirect to the Main.aspx page
            Response.Redirect("~/Main.aspx")
        Else
            'if browser is not connected,terminate all response processing.
            Response.[End]()
        End If
    End Sub
End Class

HostForLIFE.eu ASP.NET 4.8 Hosting
HostForLIFE.eu is European Windows Hosting Provider which focuses on Windows Platform only. We deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes. We have customers from around the globe, spread across every continent. We serve the hosting needs of the business and professional, government and nonprofit, entertainment and personal use market segments.



European ASP.NET Core Hosting :: Rotate Ads Without Refreshing the Page Using AdRotator in ASP.NET

clock August 20, 2019 12:18 by author Peter

This article explains the concept of the AdRotator control without the user refreshing the page and rotates the ads on a certain time interval. This article also gives a tip to fetch ad information from an XML file. The AdRotator Control presents ad images each time a user enters or refreshes a webpage. When the ads are clicked, it will navigate to a new web location. However the ads are rotated only when the user refreshes the page. In this article, we will explore how you can easily rotate ads at regular intervals, without the user refreshing the page. First of all start Visual Studio .NET And make a new ASP.NET web site using Visual Studio 2010.
 
Now you have to create a web site.
Go to Visual Studio 2010
New-> Select a website application
Click OK

Now add a new page to the website.

    Go to the Solution Explorer
    Right-click on the Project name
    Select add new item
    Add new web page and give it a name
    Click OK

We create an images folder in the application which contains some images to rotate in the AdRotator control. Now add a XML file. To do so, right-click the App_Data folder > Add New Item > 'XML File' > Rename it to adXMLFile.xml and click Add. Put this code in the .XML File.

    <?xml version="1.0" encoding="utf-8" ?> 
    <Advertisements> 
    <Ad> 
    <ImageUrl>~/Images/image1.gif</ImageUrl> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>3</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    <Ad> 
    <ImageUrl>~/images/forest_wood.JPG</ImageUrl> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>2</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    <Ad> 
    <ImageUrl>~/images/image2.gif</ImageUrl> 
    <Width>300</Width> 
    <Height>50</Height> 
    <NavigateUrl>http://www.c-sharpcorner.com/</NavigateUrl> 
    <AlternateText>C-sharpcorner Home Page</AlternateText> 
    <Impressions>3</Impressions> 
    <Keyword>small</Keyword> 
    </Ad> 
    </Advertisements> 


XML file elements

  • Here is a list and a description of the <Ad> tag items.
  • ImageUrl - The URL of the image to display.
  • NavigateUrl - The URL where the page will go after AdRotator image is clicked.
  • AlternateText - Text to display if the image is unavailable.
  • Keyword - Category of the ad, which can be used to filter for specific ads.
  • Impressions - Frequency of ad to be displayed. This number is used when you want some ads to be displayed more frequently than others.
  • Height - Height of the ad in pixels.
  • Width - Width of the ad in pixel.

Now drag and drop an AdRotator control from the toolbox to the .aspx and bind it to the advertisement file. To bind the AdRotator to our XML file, we will make use of the "AdvertisementFile" property of the AdRotator control as shown below:
    <asp:AdRotator 
    id="AdRotator1" 
    AdvertisementFile="~/adXMLFile.xml" 
    KeywordFilter="small" 
    Runat="server" /> 


To rotate the ads without refreshing the page, we will add some AJAX code to the page.
    <Triggers> 
    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" /> 
    </Triggers> 


The .aspx code will be as shown below.
 
Now drag and drop an UpdatePanel and add an AdRotator control into it. The DataList code looks like this:
    <%@ Page Language="C#" AutoEventWireup="true" CodeFile="adrotator.aspx.cs" Inherits="adrotator" %> 
    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
    <html xmlns="http://www.w3.org/1999/xhtml"> 
    <head runat="server"> 
    <title></title> 
    </head> 
    <body> 
    <form id="form1" runat="server"> 
    <div> 
    <asp:ScriptManager ID="ScriptManager1" runat="server" /> 
    <asp:Timer ID="Timer1" Interval="1000" runat="server" /> 
    <asp:UpdatePanel ID="up1" runat="server"> 
    <Triggers> 
    <asp:AsyncPostBackTrigger ControlID="Timer1" EventName="Tick" /> 
    </Triggers> 
    <ContentTemplate> 
    <asp:AdRotator ID="AdRotator1" AdvertisementFile="~/adXMLFile.xml" KeywordFilter="small" 
    runat="server" /> 
    </ContentTemplate> 
    </asp:UpdatePanel> 
    </div> 
    </form> 
    </body> 
    </html> 


Now run the application and test it. The AdRotator control rotates the ads without the user refreshing the page and rotates the ads on a certain time interval



European ASP.NET Core Hosting :: Session Wrapper Design Pattern For ASP.NET Core

clock August 14, 2019 11:11 by author Peter

In this article, we will learn to access the Session data in a Typed manner by getting IntelliSense support. We learned how to use Session in ASP.NET Core. In this article, we'll learn about Session Wrapper design pattern to ease the access of Session. In short, we'll make our access of session "Typed". Also, we may apply any validation or constraint in this wrapper class.

Step 1 - Create a Session Manager class

In this example, we are going to store two items in Session (i.e. ID & LoginName).
We are injecting IHttpContextAccessor so that we can access the Session variable.
We are creating properties which are actually accessing Session variable and returning the data or writing the data to Session.
We have added one helping property "IsLoggedIn" which is using other properties to make a decision. We may have more such helping/wrapper properties.
using Microsoft.AspNetCore.Http;

public class SessionManager 

    private readonly ISession _session; 
    private const String ID_KEY = "_ID"; 
    private const String LOGIN_KEY = "_LoginName"; 
    public SessionManager(IHttpContextAccessor httpContextAccessor) 
    { 
        _session = httpContextAccessor.HttpContext.Session; 
    } 

    public int ID 
    { 
        get 
        { 
            var v = _session.GetInt32(ID_KEY); 
            if (v.HasValue) 
                return v.Value; 
            else 
                return 0; 
        } 
        set 
        { 
            _session.SetInt32(ID_KEY, value); 
        } 
    } 
    public String LoginName 
    { 
        get 
        { 
            return _session.GetString(LOGIN_KEY); 
        } 
        set 
        { 
            _session.SetString(LOGIN_KEY, value); 
        } 
    } 
    public Boolean IsLoggedIn 
    { 
        get 
        { 
            if (ID > 0) 
                return true; 
            else 
                return false; 
        } 
    } 
}
 

Step 2
Registering IHttpContextAccessor and SessionManager in Startup file.
services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); 
services.AddScoped<SessionManager>(); 


Step 3
Injecting SessionManager in your classes. Here is an example of Controller class but in the same way, it can be injected in non-controller classes too.
private readonly SessionManager _sessionManager; 
public HomeController(SessionManager sessionManager) 

  _sessionManager = sessionManager; 


Step 4
Using SessionManager to access Session Data,
_sessionManager.ID = 1; 
_sessionManager.LoginName = dto.Login; 

if(_sessionManager.IsLoggedIn == true) 

ViewBag.Login = _sessionManager.LoginName; 
return View(); 


Conclusion
This wrapper pattern helps using Session without worrying about KeyNames & Makes access easier. It also helps you apply different conditioning and constraints in a wrapper class.

 



About HostForLIFE.eu

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