Ehsan Ghanbari

Experience, DotNet, Solutions

Enabling the CORS in Asp.net Core

As I'm talking with Asp.net core these days, so I'm supposed to be eager about that! In asp.net core, in order to enable the CORS, you should refer to application startup and ConfigureServices and add the following configuration:

 

 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.Configure<CookiePolicyOptions>(options =>

            {

                // This lambda determines whether user consent for non-essential cookies is needed for a given request.

                options.CheckConsentNeeded = context => true;

                options.MinimumSameSitePolicy = SameSiteMode.None;

            });


            services.AddCors(o => o.AddPolicy("MyPolicyName", builder =>

            {

                builder.AllowAnyOrigin()

                       .AllowAnyMethod()

                       .AllowAnyHeader();

            }));

 
            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();


            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

        }

 

 Now for applying the above policy in your controller or action, you just need to use it via attribute:

 

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

using Microsoft.AspNetCore.Cors;

using Microsoft.AspNetCore.Mvc;

 

namespace WebApplication3.Controllers

{

    [EnableCors(policyName: "MyPolicyName")]

    public class DefaultController : Controller

    {

        [EnableCors(policyName: "MyPolicyName")]

        public IActionResult Index()

        {

            return View();

        }

    }

}

 

And, in order to apply for every request, you can config it like below in startup class: 

 


 // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)

        {

            app.UseCors("MyPolicyName");

 

            if (env.IsDevelopment())

            {

                app.UseDeveloperExceptionPage();

            }

            else

            {

                app.UseExceptionHandler("/Error");

                app.UseHsts();

            }

 

            app.UseHttpsRedirection();

            app.UseStaticFiles();

            app.UseCookiePolicy();

 

            app.UseMvc();

        }

 



HttpContext in asp.net core

Accessing to HttpContext in asp.net core application is just like before, for example:

 

 public class MyController : Controller

    {

        [HttpGet]

        public ActionResult Show()

        {

            var user = HttpContext.User;

            return View();

        }

    }

 

 But HttpContext is not available everywhere in your solution! For IHttpContextAccessor. If you are using the default dependency injection of Ap.net Core then you should example to access to HttpContext in layers rather than web, you should inject a new interface of asp.net core named firstly resolve the mentioned interface in it:

 

public void ConfigureServices(IServiceCollection services)

        {

            services.Configure<CookiePolicyOptions>(options =>

            {

                // This lambda determines whether user consent for non-essential cookies is needed for a given request.

                options.CheckConsentNeeded = context => true;

                options.MinimumSameSitePolicy = SameSiteMode.None;

            });

            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

        }

 

Now you can inject the interface wherever you are going to use HttpContext:

 

   public interface ISampleService

    {

    }

 

    public class SampleService : ISampleService

    {

        private readonly IHttpContextAccessor _httpContextAccessor;

 

        public SampleService(IHttpContextAccessor httpContextAccessor)

        {

            _httpContextAccessor = httpContextAccessor;

        }

    }

 

To tell the truth, I don't like this kind of using HttpContext in the outside scope of the controller. It's an antipattern in my point of view because HttpContext and every related thing to the web should live in the web project. By the way! Using HttpContext in Razor view engine is just like before!



Disable directory browsing in asp.net core

In asp.net applications, directory browsing has enabled some versions and you let the users see all of the content and structure of your application like the picture below:

To the best of my knowledge, in order to disable the directory browsing, there are two ways: by web.config and IIS. In web.config file you just need to add the following piece of code:

 

    <system.webServer>
      <directoryBrowse enabled="false" />
    </system.webServer>

 

and In IIS, you have to disable the configuration manually:

 

 

Actually, both of them are the same. But in asp.net core, as the structure has been changed, you can handle the mentioned feature by code. In web asp.net core, static files are located in a folder named wwwroot. In the configure method of Startup class you can call the UseFileServer() and set the enableDirectoryBrowsing as false:

 

      public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Error");
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();
            app.UseMvc();
            app.UseFileServer(enableDirectoryBrowsing: false);
        }



Patterns, Principles, and practices of Domain-Driven Design

I don't know why I'm writing this blog post right now! I was supposed to write it when I was honored to receive this topless book as a gift by Scott Millett about 4 years ago! Now It's my send time that I'm reading this book and it's literally phenomenal one. I've read all the books written by Mr. Millett and I adore all of them. You will learn more than DDD and patterns by reading this book, and, I do believe that every single paragraph of this book deserves to be focused for several times.

 

If you are interested in software architecture and design patterns, firstly, read this book! I think you should have some architectural backgrounds in your mind, despite, everything has been covered in detail and approximately from scratch in this book.  For more information about the book you can see the table of content here and for purchasing the book you can refer to Amazon.



Basic producer and consumer by RabitMQ in .Net

RabitMQ is one of the most popular queue messages in the development world. In the basic form, for producing or so-called sending a message or an object into the queue you can use BasicPublish of the channel you have connected. As you can see in the following picture after sending the message to the queue, you can consume or so-called retrieve the message.

 

After installing erlang and rabitMQ in your machine, create a console application and copy and paste the following code!

 class Program
    {
        static void Main(string[] args)
        {
            Producer();
            Consumer();
        }

        public static void Producer()
        {
            var factory = new ConnectionFactory() { HostName = "localhost" };
            using (var connection = factory.CreateConnection())
            using (var channel = connection.CreateModel())
            {
                channel.QueueDeclare(queue: "hello", durable: false, exclusive: false, autoDelete: false, arguments: null);

                string message = "Thid first element of the channel!";
                var body = Encoding.UTF8.GetBytes(message);

                channel.BasicPublish(exchange: "", routingKey: "hello", basicProperties: null, body: body);
                Console.WriteLine(" [x] Sent {0}", message);
            }
        }

        public static void Consumer()
        {
            var factory = new ConnectionFactory() { HostName = "localhost" };
            using (var connection = factory.CreateConnection())
            using (var channel = connection.CreateModel())
            {
                channel.QueueDeclare(queue: "hello", durable: false, exclusive: false, autoDelete: false, arguments: null);

                Console.WriteLine(" [*] Waiting for messages.");

                var consumer = new EventingBasicConsumer(channel);

                consumer.Received += (model, ea) =>
                {
                    var body = ea.Body;
                    var message = Encoding.UTF8.GetString(body);
                    Console.WriteLine(" [x] Received {0} successfully", message);
                };

                channel.BasicConsume(queue: "hello", autoAck: true, consumer: consumer);

                Console.WriteLine(" Press enter to exit.");
                Console.ReadLine();
            }
        }
    }

Rather than BasicPublish, there is also a BasicConsume to get the message from queue! This was just a simple usage of RabitMQ. I will post some advanced usages of RabitMQ in the future.

 



About Me

Ehsan Ghanbari

Hi! my name is Ehsan. I'm a developer, passionate technologist, and fan of clean code. I'm interested in enterprise and large-scale applications architecture and design patterns. I'm spending a lot of my time on software architecture. Since 2008, I've been as a developer for companies and organizations and I've been focusing on Microsoft ecosystem all the time. During the Read More

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