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European ASP.NET Core Hosting :: How to Use AutoMapper in Asp.Net Core Application

clock December 10, 2019 11:46 by author Scott

This is only brief tutorial about how to use AutoMapper in Asp Net Core 3.0 application. Automapper is a very popular Object-to-Object mapping library that can be used to map objects.

How to use automapper in Asp.Net Core 3.0 application

Let’s see how to use automapper in Asp Net Core 3.0 application using a very simple example.

1. First step you need to do is please make sure you install Asp.net Core 3.0 application à Create a new project button à then choose “ASP.NET Core Web Application” template à click “Next” button and then enter your Project name. Please see the image below for further information

 

2. Install AutoMapper in Asp.Net Core 3.0 Application 

Now, in this step, we will install AutoMapper in our project. So, go to visual studio and then go to “Tools” from the menu and then select “NuGet Package Manager” and then choose “Manager NuGet Packages for Solution”. Now, go to “Browse” tab and then install this below package as you do see below in the screenshot.

Install-Package AutoMapper.Extensions.Microsoft.DependencyInjection

3. Configure AutoMapper in Asp.net Core 3.0 Application

Go to project folder structure, and then go to Startup class and then add some changes as you do see below in the code file’s Line # 11 and Line # 26.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.HttpsPolicy;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using AutoMapper;
namespace AspNetCore3AutoMapper
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }
        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews();
            services.AddAutoMapper(typeof(Startup));
        }
        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }
            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseRouting();
            app.UseAuthorization();
            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllerRoute(
                    name: "default",
                    pattern: "{controller=Home}/{action=Index}/{id?}");
            });

        }
    }
}

4. Create a Model Class and Data Transfer Object Class

Now, in this step , we will create two classes. One is Model class and the other one is Dto(Data Transfer Object) class. So, go to Models’ folder and then right click on the folder name and then add a new class with the name of “Employee” and then write some properties as you do see below in the code.

public class Employee
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Department { get; set; }
    }

Now, again add a new class with the name of “EmployeeDto” as you do see below in the file.

public class EmployeeDto
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Department { get; set; }
    }

5. Add relation of Employee class with EmployeeDto class

Now, in this step, we will see how to add relation between a domain class and a Dto class. So, again add a new class (E.g. AutoMapping.cs) and then write some code as you do see below in the code.

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

namespace AspNetCoreAutoMapper.Models
{
    public class AutoMapping : Profile
    {
        public AutoMapping()
        {
            CreateMap<Employee, EmployeeDto>();
        }
    }
}

Let’s understand the above code.

Line # 9: In this line, we are inheriting AutoMapping class from Profile.

Line # 13: In this line, we are mapping our Employee and EmployeeDto Classes.

6. Map Employee class with EmployeeDto Controller

We will see how to map Employee class with EmployeeDto class within the Home Controller. So, go to HomeController and then go to Index method and then write some code as you do see below in the file.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using AspNetCore3AutoMapper.Models;
using AutoMapper;

namespace AspNetCore3AutoMapper.Controllers
{
    public class HomeController : Controller
    {
        private readonly IMapper _mapper;
        public HomeController(IMapper mapper)
        {
            _mapper = mapper;
        }
        public IActionResult Index()
        {
            var empObj = new Employee();
            empObj.Id = 1;
            empObj.Name = "Scott";
            empObj.Department = "MM";
            var employeeDto = _mapper.Map<EmployeeDto>(empObj);
            return View(employeeDto);
        }
    }
}

Let’s understand the above code.

Line # 15 to 19: In this block of code, we are injecting IMapper interface. This will help us to use our configured mappings.

Line # 22 to 25: In this block of code, we are initializing Employee object.

Line # 26: In this line, we are using IMapper interface that we have injected into our constructor to call the Map method. And we are giving the type that we want to map and the object that we want to map from.

Line # 27: In this line, we are returning the EmployeeDto object to the view.

Now, go to Index view and access the returning values from the Index method as you do see below in the file.

@model EmployeeDto
@{
    ViewData["Title"] = "Home Page";
}
<div>
    <h1>ID: @Model.Id</h1>
    <h1>Name: @Model.Name</h1>
    <h1>Department: @Model.Department</h1>
</div>

Now, run your project by pressing f5 and then you will see the output

Or you can install this package by using this below command in Package Manager Console as you do see below in the screenshot.



European ASP.NET Core Hosting :: How to use AutoWrapper.Server?

clock December 4, 2019 11:16 by author Peter

If you are using AutoWrapper for generating a consistent Http response for your ASP.NET Core API's and you have some server-side applications (.NET Clients) that consume the Response, chances are you are forced to create a schema to properly deserialize the ApiResponse to your Model. The idea behind this project was based on community feedback by dazinator. It occurs to me as well that this might be a common scenario. Big thanks to dazinator!

AutoWrapper.Server is simple library that enables you unwrap the Result property of the AutoWrapper's ApiResponse object in your C# .NET Client code. The goal is to deserialize the Result object directly to your matching Model without having you to create the ApiResponse schema.

Installation
1) Download and Install the latest AutoWrapper.Server from NuGet or via CLI:
PM> Install-Package AutoWrapper.Server -Version 2.0.0 

2) Declare the following namespace in the class where you want to use it.
using AutoWrapper.Server; 

Sample Usage
[HttpGet] 
public async Task<IEnumerable<PersonDTO>> Get()   

    var client = HttpClientFactory.Create(); 
    var httpResponse = await client.GetAsync("https://localhost:5001/api/v1/persons"); 
 
    IEnumerable<PersonDTO> persons = null; 
    if (httpResponse.IsSuccessStatusCode) 
    { 
        var jsonString = await httpResponse.Content.ReadAsStringAsync(); 
        persons = Unwrapper.Unwrap<IEnumerable<PersonDTO>>(jsonString); 
    } 
 
    return persons; 


If you are using the [AutoWrapperPropertyMap] to replace the default Result property to something else like Payload, then you can use the following overload method below and pass the matching property:
Unwrapper.Unwrap<IEnumerable<PersonDTO>>(jsonString, "payload"); 


Using the UnwrappingResponseHandler

Alternatively you can use the UnwrappingResponseHandler like below:
[HttpGet] 
public async Task<IEnumerable<PersonDTO>> Get()   

    var client = HttpClientFactory.Create(new UnwrappingResponseHandler()); 
    var httpResponse = await client.GetAsync("https://localhost:5001/api/v1/persons"); 
 
    IEnumerable<PersonDTO> persons = null; 
    if (httpResponse.IsSuccessStatusCode) 
    { 
        var jsonString = await httpResponse.Content.ReadAsStringAsync(); 
        persons = JsonSerializer.Deserialize<IEnumerable<PersonDTO>>(jsonString); 
    } 
 
    return persons; 


You can also pass the matching property to the handler like in the following:

var client = HttpClientFactory.Create( new UnwrappingResponseHandler("payload")); 

That's it. If you used AutoWrapper or if you find this useful, please give it a star to show your support and share it to others.



European ASP.NET Core Hosting :: PopupBox For Debug Only

clock November 28, 2019 11:38 by author Peter

When debugging I feel a need to popup values from variables. I know that Visual Studio is cool but I feel the need to use it just typing. So I design an extension method to make it easy. You can add your custom objects, or Windows objects, and make a clause to show it or not. The message is shown only in DEBUG time.

See this sample,
using System; 
using System.Net.Mail; 
using System.Windows.Forms; 
 
namespace DebugPopup 

    public partial class FrmSample : Form 
    { 
        public FrmSample() => InitializeComponent(); 
 
        private void Form1_Load(object sender, EventArgs e) 
        { 
            var eml = new MailAddress("test@google.com", "test"); 
 
            eml.PopupBox(); 
 
            var n = 0; 
 
            n.PopupBox(); 
 
            Handle.PopupBox(); 
 
            decimal.Zero.PopupBox(n==0, "n is equals zero!"); 
         
        } 
 
        private void button1_Click(object sender, EventArgs e) 
        { 
            ((Button)sender).PopupBox(); 
        } 
    } 


It 's an extension method that you only need to add.PopupBox() from the Visual Studio property menu.
You can add custom types and the message will be shown only in DEBUG mode, I mean that in production there will be no message.

This is the main code,
using System.Windows.Forms; 
using System.Net.Mail; 
using System.Diagnostics; 
 
/// <summary> 
/// Author: Jefferson Saul G. Motta 
/// 10-24-2019 20:50 
/// Uses the System 
/// </summary> 
namespace System 

 
    /// <summary>   
    /// This is my real code that I make to debug easly 
    /// You can copy to .NET Core as Well 
    /// If you are debugging in a local IIS (ASP.NET WebForms) 
    /// The popup will raises too 
    /// C# 7.3 and C# 8.0 
    /// About extensions: http://www.c-sharpcorner.com/blogs/extension-method-in-c-sharp3 
    /// </summary> 
    public static class ExtensionMethodStrings 
    { 
 
         
        /// <summary> 
        /// Popup for int value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this int value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
         
        /// <summary> 
        /// Popup for decimal value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this decimal value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
         
        /// <summary> 
        /// Popup for IntPtr value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this IntPtr value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message);         
         
        /// <summary> 
        /// Popup for double value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this double value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
         
        /// <summary> 
        /// Popup for long value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this long value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
         
        /// <summary> 
        /// Popup for string value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this string value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
         
         
        /// <summary> 
        /// Popup for string value if contem a string 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="contem"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this string value, in string contem, in string message = "") => PopupIt($"Value: {value}", value.ContemUpper(contem), message);         
         
        /// <summary> 
        /// Popup for bool value 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="showIf"></param> 
        /// <param name="message"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this bool value, in bool showIf = true, in string message = "") => PopupIt($"Value: {value}", showIf, message); 
 
        /// <summary> 
        /// Check if exist comparing uppper text 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="text"></param> 
        /// <returns></returns> 
        private static bool ContemUpper(this string value, string text) => string.IsNullOrEmpty(value) || string.IsNullOrEmpty(text) ? false : value.ToUpper().IndexOf(text.ToUpper()) != -1; 
 
 
        /// <summary> 
        /// Sample 
        /// You can add another controls or objects 
        /// </summary> 
        /// <param name="button"></param> 
        /// <param name="showIf"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this Button button, in bool showIf = true) => PopupIt(button.Text, showIf); 
 
        /// <summary> 
        /// Sample 
        /// You can add another controls or objects 
        /// Test with MailAddress 
        /// </summary> 
        /// <param name="eml"></param> 
        /// <param name="showIf"></param> 
        /// <returns></returns> 
        public static bool PopupBox(this MailAddress eml, in bool showIf = true) => PopupIt(eml.Address, showIf); 
 
        /// <summary> 
        /// Add the label if value not is empty 
        /// </summary> 
        /// <param name="value"></param> 
        /// <param name="label"></param> 
        /// <returns></returns> 
        private static string LabelIfNotEmpty(this string value, string label) => string.IsNullOrEmpty(value) ? "" : $"{label}:{value}"; 
 
        /// <summary> 
        /// Show popup only for DEBUG 
        /// </summary> 
        /// <param name="message"></param> 
        /// <param name="showIf"></param> 
        /// <param name="messageExtra"></param> 
        /// <returns></returns> 
        private static bool PopupIt(string message, in bool showIf = true, in string messageExtra = "") 
 
#if (DEBUG) 
        { 
            // Show popup if true 
            if (showIf) 
            { 
                Debug.WriteLine($"{messageExtra.LabelIfNotEmpty("Extra message:")}{message}"); 
             
                // Optional: 
                MessageBox.Show($"{messageExtra.LabelIfNotEmpty("Extra message:")}{message}"); 
             
            } 
            // showIf  
            return showIf; 
        } 
#else 
            // on Releases returns false 
            => false; 
 
#endif 
 
    } 
 
}



European ASP.NET Core Hosting :: AutoWrapper Version 2.1.0 Released

clock November 12, 2019 10:42 by author Peter

AutoWrapper 2.1.0 has been released with newly features added based on community feedback. Here are the newly features added:

  • Added [AutoWrapIgnore] action filter attribute.
  • Added support to override non-success message when using IActionResult return types.
  • Added EnableResponseLogging and EnableExceptionLogging options to turn off auto logging.
  • Added UnAuthorize and BadRequest message for HandleNotSucessAsync() method response.

Using IActionResult Return Types
AutoWrapper now supports IActionResult return types that allows you to return non successful requests such as BadRequest, NotFound, UnAuthorize and etc.
For example:
[Route("{id:long}")] 
[HttpGet] 
public async Task<IActionResult> Get(long id)   

    var person = await _personManager.GetByIdAsync(id); 
    if (person != null) 
    { 
        return Ok(person); 
    } 
    else 
        return NotFound($"Record with id: { id } does not exist."); 


Another example such as:
return Unauthorized("Access token is invalid.");   
return BadRequest("SomeField is null.");   


AutoWrapIgnore Attribute
You can now use the [AutoWrapIgnore] filter attribute for enpoints that you don't want to be wrapped.
For example:
[HttpGet] 
[AutoWrapIgnore] 
public async Task<IActionResult> Get()   

    var data = await _personManager.GetAllAsync(); 
    return Ok(data); 


or
[HttpGet] 
[AutoWrapIgnore] 
public async Task<IEnumerable<Person>> Get()   

    return await _personManager.GetAllAsync(); 


Turn-off Default Logging
You can now turn off Logging by setting EnableResponseLogging and EnableExceptionLogging options to false in AutoWrapper options.
For example:
app.UseApiResponseAndExceptionWrapper(new AutoWrapperOptions {   
              EnableResponseLogging = false,  
              EnableExceptionLogging = false  
}); 


That's it. Feel free to request an issue on github if you find bugs or request a new feature. Your valuable feedback is much appreciated to better improve this project. If you find this useful, please give it a star to show your support for this project.



European ASP.NET Core Hosting :: All About Sessions In ASP.NET Core

clock November 5, 2019 10:53 by author Peter

HTTP is a stateless protocol, so we need some mechanism to maintain our App State. Server Side Session has been a way to maintain our state on the server side. In this article we'll see what differences ASP.NET Core has introduced regarding SESSION.

We'll quickly discuss how we used to use Sessions before ASP.NET Core and then we'll see how to access Sessions in ASP.NET Core.

Session In Pre-ASP.NET Core era
You get Session functionality by default (without adding any package)
Previously, you would have accessed Session by -

    Session variable in your Controllers/Forms
    System.Web.HttpContext.Current.Session in places where you don't have direct access to the Session variable.

Anything you store in session is stored as Object. You store values in Key/Value format.

    Session["mydata"] = 10;  

Or to access on those places where Session is not available (e.g. Non-Controller classes)

    System.Web.HttpContext.Current.Session["mydata"] = 10;  

Quite difficult to mock Session Object for Unit Testing

Session in ASP.NET Core 2.2
Now, Session is not available by default.
You need to add the following package. Meta package by default provides you this.

    <PackageReference Include="Microsoft.AspNetCore.Session" Version="2.2.0" /> 
In Startup.ConfigureServices, you need to add the following to register services with DI Container.
    services.AddDistributedMemoryCache();//To Store session in Memory, This is default implementation of IDistributedCache   
    services.AddSession(); 

In Startup.Configure, you need to add the following (before UseMVC) to add Session Middleware.

    app.UseCookiePolicy();     
    app.UseSession();     
    app.UseMvc(routes =>   

Make sure the following is also there (It is added by default when you use ASP.NET Core MVC Template).

    app.UseCookiePolicy();  

ASP.NET Core 2.2 onwards adds Cookie Consent (true) in the Startup file. When an application runs, the user needs to accept Cookie Consent on screen. When the user accepts the policy on the page, it creates a consent cookie. It is to follow GDPR and to give control to the user if the user wants to store cookies from a site or not. If the user doesn't accept that, Session does not work because Session requires a cookie to send/receive session Id. You may face this issue while working with ASP.NET Core MVC default template.

How to access Session in Controller?

You will notice that you don't have "Session" variable available now. Controller now has a property "HttpContext" which has "Session" variable. So, you can access session in controller by using the following code.

var a = this.HttpContext.Session.GetString("login");   
HttpContext.Session.SetString("login", dto.Login); 


How to access Session in Non-Controller class?

Now, you don't have System.Web.HttpContext.Current.Session in ASP.NET Core. To access session in non-controller class -

First, register the following service in Startup.ConfigureServices;

    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>(); 

Now, register a class (example - TestManager) where you want to access the Session in Startup.ConfigureServices;
    services.AddScoped<TestManager>(); 
Note
You may use AddTransient or AddSingleton according to your logic.

Now, in TestManager class, add the following code.
    private readonly IHttpContextAccessor _httpContextAccessor;   
    private readonly ISession _session;   
    public TestManager(IHttpContextAccessor httpContextAccessor)   
       {   
            _httpContextAccessor = httpContextAccessor;   
            _session = _httpContextAccessor.HttpContext.Session;   
        } 


The above code is receiving IHttpContextAccessor object through dependency injection and then, it is storing Sessions in a local variable.

How to access Session in View file?

Add the following at the top of your View file.
@using Microsoft.AspNetCore.Http   
@inject IHttpContextAccessor httpContextAccessor  


Then, you may access the Session variable in your View like following.
@httpContextAccessor.HttpContext.Session.GetString("login")  

What else is changed regarding Session?

Session is non-locking now.
A session is not created until you have at least one value in it
You need to use functions to get & set data. Array syntax is not supported now.
Now, ISession only provides Get & Set method which takes & returns data in Byte Array format.
If you want to store data in the String format, you may add the following in your file and use extension methods.
    using Microsoft.AspNetCore.Http;  
It exposes the new extension methods.
    SetInt32   
    GetInt32   
    SetString   
    GetString   
Under the hood, these covert the data into bytes.

You may also write your own extension methods. For example, the following Extension Methods help you store & retrieve any complex type.
    public static class SessionExtensions       
        {       
            public static void Set<T>(this ISession session, string key, T value)       
            {       
                session.Set<(key, JsonConvert.SerializeObject(value));       
            }       
           
            public static T GetObject<T>(this ISession session, string key)       
            {       
                var value = session.GetString(key);       
                return value == null ? default(T) : JsonConvert.DeserializeObject<T>(value);       
            }       
        }  


In the next article, we'll learn about SESSION Wrapper Design Pattern.

Summary

Session concepts are similar to what we've seen in earlier .NET Frameworks. The real difference is that now, it is cleaner & more flexible to use.

 



European ASP.NET Core Hosting :: Error When Published ASP.NET Core? See Below Tips!

clock November 5, 2019 05:38 by author Scott

At the past few years, we have discussed about common error that you can find when published .NET Core, the most common error is 502.5 – process failure error.

Startup errors with ASP.NET Core don’t provide much information either, at least not in a production environment. Here are 7 tips for understanding and fixing those errors.

1. There are two types of startup errors.

There are unhandled exceptions originating outside of the Startup class, and exceptions from inside of Startup. These two error types can produce different behavior and may require different troubleshooting techniques.

2. ASP.NET Core will handle exceptions from inside the Startup class.

If code in the ConfigureServices or Configure methods throw an exception, the framework will catch the exception and continue execution.

Although the process continues to run after the exception, every incoming request will generate a 500 response with the message “An error occurred while starting the application”.

Two additional pieces of information about this behavior:

- If you want the process to fail in this scenario, call CaptureStartupErrors on the web host builder and pass the value false.

- In a production environment, the “error occurred” message is all the information you’ll see in a web browser. The framework follows the practice of not giving away error details in a response because error details might give an attacker too much information. You can change the environment setting using the environment variable ASPNETCORE_ENVIRONMENT, but see the next two tips first. You don’t have to change the entire environment to see more error details.

3. Set detailedErrors in code to see a stack trace.

The following bit of code allows for detailed error message, even in production, so use with caution.

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
           .CaptureStartupErrors(true) // the default
           .UseSetting("detailedErrors", "true")
           .UseStartup<Startup>();

4. Alternatively, set the ASPNETCORE_DETAILEDERRORS environment variable.

Set the value to true and you’ll also see a stack trace, even in production, so use with caution.

5. Unhandled exceptions outside of the Startup class will kill the process.

Perhaps you have code inside of Program.cs to run schema migrations or perform other initialization tasks which fail, or perhaps the application cannot bind to the desired ports. If you are running behind IIS, this is the scenario where you’ll see a generic 502.5 Process Failure error message.

These types of errors can be a bit more difficult to track down, but the following two tips should help.

6. For IIS, turn on standard output logging in web.config.

If you are carefully logging using other tools, you might be able to capture output there, too, but if all else fails, ASP.NET will write exception information to stdout by default. By turning the log flag to true, and creating the output directory, you’ll have a file with exception information and a stack trace inside to help track down the problem.

The following shows the web.config file created by dotnet publish and is typically the config file in use when hosting .NET Core in IIS. The attribute to change is the stdoutLogEnabled flag.

<system.webServer>
  <handlers>
    <add name="aspNetCore" path="*" verb="*" modules="AspNetCoreModule" resourceType="Unspecified" />

  </handlers>
  <aspNetCore processPath="dotnet" arguments=".\codes.dll"
              stdoutLogEnabled="true" stdoutLogFile=".\logs\stdout" />
</system.webServer>

Important: Make sure to create the logging output directory.

Important: Make sure to turn logging off after troubleshooting is complete.

7. Use the dotnet CLI to run the application on your server.

If you have access to the server, it is sometimes easier to go directly to the server and use dotnet to witness the exception in real time. There’s no need to turn on logging or set and unset environment variables.

Summary

Debugging startup errors in ASP.NET Core is a simple case of finding the exception. In many cases, #7 is the simplest approach that doesn’t require code or environment changes. FYI, we also have support latest ASP.NET Core on our hosting environment. Feel free to visit our site at https://www.hostforlife.eu.



European ASP.NET Core 3 Hosting :: Simple Steps to Migrate Your ASP.NET Core 2 to ASP.NET Core 3

clock October 25, 2019 07:18 by author Scott

.NET Core always interesting. In the past few months, we have just launched ASP.NET Core 2.2 on our hosting environment, and now Microsoft has support latest ASP.NET Core 3. This post will be taking the Contacts project used in the ASP.NET Basics series and migrating it from .NET Core 2.2 to .NET Core 3.0.

Installation

If you are a Visual Studio user you can get .NET Core 3.0 by installing at least Visual Studio 16.3. For those not using Visual Studio, you can download and install .NET Core 3.0 SDK from here. As with previous versions, the SDK is available for Windows, Linux, and Mac.

After installation is complete you can runt the following command from a command prompt to see all the versions of the .NET Core SDK you have installed.

dotnet --list-sdks

You should see 3.0.100 listed. If you are like me you might also see a few preview versions of the SDK that can be uninstalled at this point.

Project File Changes

Right-click on the project and select Edit projectName.csproj.

Change the TargetFramework to netcoreapp3.0.

Before:
<TargetFramework>netcoreapp2.2</TargetFramework>

After:
<TargetFramework>netcoreapp3.0</TargetFramework>

The packages section has a lot of changes. Microsoft.AspNetCore.App is now gone and part of .NET Core without needing a specific reference. The other thing to note is that Entity Framework Core is no longer “in the box” so you will see a lot of references add to make Entity Framework Core usable.

Before:
<PackageReference Include="Microsoft.AspNetCore.App" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="2.2.0" PrivateAssets="All" />
<PackageReference Include="Swashbuckle.AspNetCore" Version="4.0.1" />

After:
<PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.0.0" />
<PackageReference Include="Microsoft.AspNetCore.Identity.UI" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.0.0" />
<PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0" />
<PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.0.0" PrivateAssets="All" />
<PackageReference Include="Swashbuckle.AspNetCore" Version="5.0.0-rc4" />

The last thing to note is that Swashbuckle doesn’t have a final version ready for .NET Core 3 so you will have to make sure you are using version 5 rc2 at a minimum.

The following is my full project file for reference.

<Project Sdk="Microsoft.NET.Sdk.Web">
  <PropertyGroup>
    <TargetFramework>netcoreapp3.0</TargetFramework>
    <AspNetCoreHostingModel>InProcess</AspNetCoreHostingModel>
    <UserSecretsId>aspnet-Contacts-cd2c7b27-e79c-43c7-b3ef-1ecb04374b70</UserSecretsId>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="3.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore" Version="3.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.EntityFrameworkCore" Version="3.0.0" />
    <PackageReference Include="Microsoft.AspNetCore.Identity.UI" Version="3.0.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.SqlServer" Version="3.0.0" />
    <PackageReference Include="Microsoft.EntityFrameworkCore.Tools" Version="3.0.0" />
    <PackageReference Include="Microsoft.VisualStudio.Web.CodeGeneration.Design" Version="3.0.0" PrivateAssets="All" />
    <PackageReference Include="Swashbuckle.AspNetCore" Version="5.0.0-rc4" />
  </ItemGroup>
</Project>

Program Changes

In Program.cs some changes to the way the host is constructed. The over version may or may not have worked, but I created a new app and pulled this out of it just to make sure I’m using the current set up.

using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Hosting;
namespace Contacts
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateHostBuilder(args).Build().Run();
        }
        public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureWebHostDefaults(webBuilder =>
                                          {
                                              webBuilder.UseStartup<Startup>();
                                          });
    }
}

Startup Changes

In Startup.cs we have quite a few changes to make. As long as you haven’t do any customization in the constructor you can replace it with the following.

public Startup(IConfiguration configuration)
{
        Configuration = configuration;
}

Next, they type on the configuration property changed from IConfigurationRoot to IConfiguration.

Before:
public IConfigurationRoot Configuration { get; }

After:
public IConfiguration Configuration { get; }

Moving on to the ConfigureServices function has a couple of changes to make. The first is a result of updating to the newer version of the Swagger package where the Info class has been replaced with OpenApiInfo.

Before:
services.AddSwaggerGen(c =>
{
        c.SwaggerDoc("v1", new Info { Title = "Contacts API", Version = "v1"});
});

After:
services.AddSwaggerGen(c =>
{
        c.SwaggerDoc("v1", new OpenApiInfo { Title = "Contacts API", Version = "v1" })
});

Next, we are going to move from using UserMvc to the new AddControllersWithViews which is one of the new more targeted ways to add just the bits of the framework you need.

Before:
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

After:
services.AddControllersWithViews();

Now in the Configure function, the function signature needs to be updated and the logging factory bits removed. If you do need to configure logging that should be handled as part of the HostBuilder.

Before:
public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
loggerFactory.AddConsole(Configuration.GetSection("Logging"));
      loggerFactory.AddDebug();

After:
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{

For the next set of changes, I’m just going to show the result and not the before. The UseCors may or may not apply but the addition of UserRouting and the replacement of UseMvc with UserEndpoint will if you want to use the new endpoint routing features.

app.UseStaticFiles();
app.UseRouting();
app.UseCors(builder =>
            {
                builder.AllowAnyHeader();
                builder.AllowAnyMethod();
                builder.AllowAnyOrigin();
            }
           );
app.UseAuthentication();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
                 {
                     endpoints.MapControllerRoute(
                                                  name: "default",
                                                  pattern: "{controller=Home}/{action=Index}/{id?}");
                     endpoints.MapRazorPages();
                 });

Other Miscellaneous Changes

The only other change I had was the removal of @using Microsoft.AspNetCore.Http.Authentication in a few cshtml files related to login.

 



ASP.NET Core Hosting :: How to Upload File using C# | SFTP Server

clock March 4, 2019 07:56 by author Scott

Although there are many Graphical Tools available for sending files to a server using SFTP. But as a developer, we may have a scenario where we need to upload a file to SFTP Serverfrom our Code.

A few days ago a job assigned to me was to develop a Task Scheduler for generating XML files daily on a specific time of the day & send these files on a Remote Server using File Transfer Protocol in a secure way.

In .Net Framework there are many Libraries available for uploading files to another machine using File Transfer Protocol but most of the libraries don’t work with .Net Core. In this Tutorial, we will develop a very simple SFTP client using C# for .Net Core.

Before start let’s have a quick look at SFTP.

What is SFTP?

SFTP stands for SSH File Transfer Protocol or Secure File Transfer Protocol. It is a protocol used to transfer files between remote machines over a secure shell.

 

In almost all cases, SFTP is preferable over FTP because of security features. FTP is not a secure protocol & it should only be used on a trusted network.

Choosing Library for C#

A lot of search & after testing many libraries I finally met with SSH.NET which was working perfectly with .Net Core 2.2 project & the good thing was that It does its job in a very few lines of Code.

So we’ll use SSH.NET

What is SSH.NET?

SSH.NET is an open-source library available at Nuget for .NET to work over SFTP. It is also optimized for parallelism to achieve the best possible performance. It was inspired by Sharp.SSH library which was ported from Java. This library is a complete rewrite using .Net, without any third party dependencies.

Here are the features of SSH.NET: 

Creating Project

I’m in love with VS Code right after its first release so I’m going to use VS Code for creating project to upload/transfer a file to a remote server using SFTP.

Create a console application using this command

dotnet new console

Installing SSH.NET

I won’t recommend you to install the latest version of SSH.NET. It has a bug, it can be stuck on transferring the file to the remote location.

version 2016.0.0 is perfect. 

run this command to install the library from NuGet

using package manager

Install-Package SSH.NET -Version 2016.0.0

or using .Net CLI

dotnet add package SSH.NET --version 2016.0.0

Code

Finally, It’s time to create a class for SFTP Client Code.

Create a file with the name as “SendFileToServer” & add the below code

using Renci.SshNet

public static class SendFileToServer
{
// Enter your host name or IP here
private static string host = "127.0.0.1";

// Enter your sftp username here
private static string username = "sftp";

// Enter your sftp password here
private static string password = "12345";
public static int Send(string fileName)
{
var connectionInfo = new ConnectionInfo(host, "sftp", new PasswordAuthenticationMethod(username, password));

// Upload File
using (var sftp = new SftpClient(connectionInfo)){

sftp.Connect();
//sftp.ChangeDirectory("/MyFolder");
using (var uplfileStream = System.IO.File.OpenRead(fileName)){
sftp.UploadFile(uplfileStream, fileName, true);
}
sftp.Disconnect();
}
return 0;
}
}

Now you can call this Method to transfer a file to SFTP Server like this

SendFileToServer.Send("myFile.txt");

“myFile.txt” is the name of the file which should be located in your project root directory. 



European ASP.NET Core Hosting :: How to Use HTTP-REPL tool to test WEB API in ASP.NET Core 2.2

clock February 26, 2019 07:37 by author Scott

Today there are no tools built into Visual Studio to test WEB API. Using browsers, one can only test http GET requests. You need to use third-party tools like PostmanSoapUIFiddler or Swagger to perform a complete testing of the WEB API. In ASP.NET Core 2.2, a CLI based new dotnet core global tool named “http-repl” is introduced to interact with API endpoints. It’s a CLI based tool which can list down all the routes and execute all HTTP verbs. In this post, let’s find out how to use HTTP-REPL tool to test WEB API in ASP.NET Core 2.2.

HTTP-REPL Tool to test WEB API in ASP.NET Core 2.2

The “http-repl” is a dotnet core global tool and to install this tool, run the following command. At the time of writing this post, the http-repl tool is in preview stage
and available for download at 
dotnet.myget.org

dotnet tool install -g dotnet-httprepl --version 2.2.0-* --add-source https://dotnet.myget.org/F/dotnet-core/api/v3/index.json

Once installed, you can verify the installation using the following command.

dotnet tool list -g



Now the tool is installed, let’s see how we can test the WEB API. For this tool to work properly, the prerequisite here is that your services will have Swagger/OpenAPI available that describes the service.

We need to add this tool to web browser list so that we can browse the API with this tool. To do that, follow the steps given in the below image.



The location of HTTP-REPL tool executable is "C:\Users\<username>\.dotnet\tools". Once added, you can verify it in the browser list.

Run the app (make sure HTTP REPL is selected in browser list) and you should see a command prompt window. As mentioned earlier, it’s a CLI based experience so you can use commands like dir, ls, cdand cls. Below is an example run where I start-up a Web API.

You can use all the HTTP Verbs, and when using the POST verb, you should set a default text editor to supply the JSON. You can set Visual Studio Code as default text editor using the following command.

pref set editor.command.default "C:\Program Files (x86)\Microsoft VS Code\Code.exe"

Once the default editor is set, and you fire POST verb, it will launch the editor with the JSON written for you. See below GIF.

You can also navigate to the Swagger UI from the command prompt via executing ui command. Like,

Similarly, you can also execute the DELETE and PUT. In case of PUT command, you should use following syntax and in the default code editor, supply the updated data.

> delete 2 //This would delete the record with id 2.
>
> put 2010 -h "Content-Type: application/json"

When you fire PUT command, the behavior is same as the POST verb. The text editor will open with the JSON written for you, just supply the updated value to execute PUT command.

Pros and Cons

Pros

  • Helps in debugging WEB API
  • Fast and quickly switch between API endpoints
  • Descriptive error response shown

Cons:

  • Dependency on Swagger/Open API specification
  • Not as informative as UI tools

After playing with this for a while, I strongly feel it’s command line version of the Swagger UI and it would be very handy when there are many API endpoints. You can easily navigate or switch between the APIs and execute it. 



European ASP.NET Core Hosting :: How to Measure and Report the Response Time of ASP.NET Core

clock November 8, 2018 09:57 by author Scott

Performance is a buzzword for APIs. One of the most important and measurable parameters of the API performance is the response time. In this article, we will understand how to add code to measure the response time of an API and then return the response time data to the end client.

What is the need for this?

So, let's take a moment to think why we would ever need such a feature to measure the Response time of an API. Following are some of the points that have been the inspiration for writing code to Capture response time.

  • You need to define the SLA (Service Level Agreements) for your API with your clients. The clients need to understand how much time  the API takes to respond back. The response time data over time can help us decide on an SLA for our API.
  • Management is interested in reports as to how fast or slow the application is. You need to have data to corroborate your claims. It is worth it to have reports on the performance of the application and to share it with Stakeholders.
  • The client needs to have the information of the Response time of the API so that they can track how much time is spent on the client and the Server.

You might also have encountered similar requests in your project and it is worthwhile looking at an approach to capture the response time for the API.

Where to add the code?

Let's explore a couple of approaches to capture the response time of our API focusing mostly on capturing the time spent in our API. Our objective is to calculate the time elapsed in milliseconds from the time the request is received by the Asp.net core runtime to the time the response is processed and sent back from the Server.

What factors are we ignoring?

It's important to understand that this discussion doesn't include the time spent in N/W, Time spent in IIS and Application Pool Startup. If the Application Pool wasn't up and running, then the first request can affect the overall response time of the API. There is an Application Initialization Module which we can make use of but that is out of scope for this article.

First Attempt

One very naive approach to capturing the response time of an API would be to add code to every API method at the start and end and then measure the delta to calculate the response time as shown 

// GET api/values/5   
[HttpGet]  
public IActionResult Get() {  
    // Start the watch   
    var watch = new Stopwatch();  
    watch.Start();  
    // Your actual Business logic   
    // End the watch  
    watch.Stop();  
    var responseTimeForCompleteRequest = watch.ElapsedMilliseconds;  
} 

This code should be able to calculate the time spent in an operation. But this doesn't seem to be the right approach for the following reasons.

If an API has a lot of operations, then we need to add this code to multiple places which are not good for maintainability.

This code measures the time spent in the method only, it doesn't measure the time spent on other activities like middleware, filters, Controller selection, action method selection, Model binding etc.

Second Attempt

Let's try to improve the above code by centralizing the code in one place so that it is easier to maintain. We need to execute the response time calculation code before and after a method is getting executed. If you have worked with earlier versions of Asp.net Web API, you would be familiar with concepts of Filter. Filters allow you to run code before or after specific stages in the request processing pipeline.

We will implement a filter for calculating the Response time as shown below. We will create a Filter and use the OnActionExecuting to start the timer and then stop the timer in method OnActionExecuted, thus calculating the response time of the API.

public class ResponseTimeActionFilter: IActionFilter { 
    private const string ResponseTimeKey = "ResponseTimeKey"; 
    public void OnActionExecuting(ActionExecutingContext context) { 
        // Start the timer  
        context.HttpContext.Items[ResponseTimeKey] = Stopwatch.StartNew(); 
    } 
    public void OnActionExecuted(ActionExecutedContext context) { 
        Stopwatch stopwatch = (Stopwatch) context.HttpContext.Items[ResponseTimeKey]; 
        // Calculate the time elapsed  
        var timeElapsed = stopwatch.Elapsed; 
    } 
}  

This code is not a reliable technique for calculating the response time as it doesn't address the issue of calculating the time spent in execution of middleware, controller selection, action method selection, model binding etc. The filter pipeline runs after the MVC selects the action to execute. So, it effectively doesn't instrument the time spent in the Other Asp.net pipeline. 

Third Attempt

We will use the Asp.net Core Middleware to Calculate the Response time of the API.

So, what is Middleware?

Basically, Middleware are software components which handle the Request/Response. Middleware is assembled into an application pipeline and serves in the incoming request. Each component does the following operations.

  • Chooses whether to pass the request to the next component in the pipeline. 
  • Can perform work before and after the next component in the pipeline is invoked.

If you have worked with HTTPModules or HTTPHandlers in ASP.NET, then you can think of Middleware as a replacement in ASP.NET Core. Some of the examples of middleware are -

  • MVC Middleware
  • Authentication
  • Static File Serving
  • Caching
  • CORS

 

 

We want to add code to start the timer once the request enters the ASP.NET Core pipeline and stop the timer once the response is processed by the Pipeline. Custom Middleware at the start of the request pipeline seems to be the best approach for getting the access to the request as early as possible and access until the last step is executed in the pipeline.

We will build a Response Time Middleware which we will add as the first Middleware to the request Pipeline so that we can start the timer as soon the request enters the Asp.net core pipeline.

What to do with the Response time data?

Once we capture the response time data we can process data in the following ways.

  1. Add the Response time data to a Reporting database or an analytics solution.
  2. Write the Response time data to a log file.
  3. Pass the response time data to a message queue which can further be processed by another application for reporting and analytics.
  4. Send the Response time information to the client applications consuming our Rest API using the Response headers.
  5. There may be other useful ways of using the response time data. Please leave a comment and tell me how you process the response time data in your application.

Let's write the code

We will write the code considering the following points.

  • Calculating the response time data for the API
  • Reporting the data back to client applications by passing the data in the Response headers.

Full code snippet for the ResponseTimeMiddleware is shown below.

public class ResponseTimeMiddleware { 
    // Name of the Response Header, Custom Headers starts with "X-"
 
    private const string RESPONSE_HEADER_RESPONSE_TIME = "X-Response-Time-ms";
 
    // Handle to the next Middleware in the pipeline
 
    private readonly RequestDelegate _next;
 
    public ResponseTimeMiddleware(RequestDelegate next) {
 
        _next = next;
 
    }
 
    public Task InvokeAsync(HttpContext context) {
 
        // Start the Timer using Stopwatch
 
        var watch = new Stopwatch();
 
        watch.Start();
 
        context.Response.OnStarting(() => {
 
            // Stop the timer information and calculate the time
  
            watch.Stop();
 
            var responseTimeForCompleteRequest = watch.ElapsedMilliseconds;
 
            // Add the Response time information in the Response headers.
  
            context.Response.Headers[RESPONSE_HEADER_RESPONSE_TIME] = responseTimeForCompleteRequest.ToString();
 
            return Task.CompletedTask;
 
        });
 
        // Call the next delegate/middleware in the pipeline
  
        return this._next(context);
 
    }
 
}

Explanation of the code

The interesting part happens in the InvokeAsync method, We use Stopwatch class to start the stopwatch once the requests enter into the first middleware of the request and then stop the stopwatch once the request has been processed and the response is ready to be sent back to the client. OnStarting method provides an opportunity to write a custom code to add a delegate to be invoked just before response headers will be sent to the client.

Lastly, we add the Response time information in a Custom Header. We use the X-Response-Time-msheader as a Response Header. As a convention, the Custom Header starts with an X.

Conclusion

In this article, we understood how to leverage ASP.NET middleware to manage cross-cutting concerns like measuring the response time of the APIs. There are various other useful use cases of using middleware which can help to reuse code and improve the maintainability of the application.

/p>



About HostForLIFE.eu

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 offered the latest Windows 2016 Hosting, ASP.NET Core 2.2.1 Hosting, ASP.NET MVC 6 Hosting and SQL 2017 Hosting.


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