public void ConfigureServices(IServiceCollection services) 
{ 
    // Add service and create Policy with options 
    services.AddCors(options => 
    { 
        options.AddPolicy("CorsPolicy", 
            builder => builder.AllowAnyOrigin() 
            .AllowAnyMethod() 
            .AllowAnyHeader() 
            .AllowCredentials() ); 
    }); 
     
    // Make sure MVC is added AFTER CORS 
    services.AddMvc(); 
}

services.AddCors(options =>
{
    options.AddPolicy("AllowOrigin",
            builder => builder.WithOrigins("http://localhost:55294")
                              .WithMethods("GET", "POST", "HEAD"));
});

public void Configure(IApplicationBuilder app) 
{ 
    // ... 
 
    app.UseCors("CorsPolicy"); 
     
    // ... 
     
    app.UseMvc(routes => 
    { 
        routes.MapRoute( 
            name: "default", 
            template: "{controller=Home}/{action=Index}/{id?}"); 
    }); 
}

[EnableCors("CorsPolicy")]
public class MyApiController : Controller

public void ConfigureServices(IServiceCollection services)
{
      services.AddCors();
      services.AddMvc();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
 
    app.UseCors(policyBuilder =>
    {
        string[] origins = new string[] { "http://localhost:2000", "http://localhost:2001" };
 
        policyBuilder
            .AllowAnyHeader()
            .AllowAnyMethod()
            .WithOrigins(origins);
    });
 
    app.UseMvc();
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddCors(options =>
    {
        options.AddDefaultPolicy(
            builder =>
            {
            builder
                .AllowAnyOrigin()
                .AllowAnyMethod()
                .AllowAnyHeader();
            });
          options.AddPolicy("MyCORSPolicy",
            builder =>
            {
                builder.WithOrigins("http://localhost:49373")
                                    .AllowAnyHeader()
                                    .AllowAnyMethod();
            });
     });
    services.AddMvc().AddNewtonsoftJson();
}

Access to XMLHttpRequest at 'http://localhost:22135/chat/negotiate?jwt=<removed the jwt key>' 
from origin 'http://localhost:53150' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: 
The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. 
The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.

services.AddCors(options =>
{
     options.AddPolicy("AllowAllOrigins",
         builder =>
          {
              builder
                 .AllowAnyOrigin()
                 .AllowAnyHeader()
                 .AllowAnyMethod()
                 .AllowCredentials();
          });
    });

var xhr = new XMLHttpRequest();
xhr.open('get', 'http://www.example.com/api/test');
xhr.withCredentials = true;

//In jQuery:
$.ajax({
  type: 'get',
  url: 'http://www.example.com/home',
  xhrFields: {
    withCredentials: true
}

//ES6 fetch API:
fetch(
   'http://remote-url.com/users',
   {
     'PUT',
     headers: {
          'Accept': 'application/json',
          'Content-Type': 'application/json'
     },
     mode: 'cors',
     credentials: 'include',
     body: JSON.stringify(body)
   }
)
.then((response) => response.json())
.then((response) => console.log(response))
.catch((error) => console.error(error));

[EnableCors(origins: "http://MyWebsite.com", headers: "*", methods: "*")]
//is not the same as this:
[EnableCors(origins:"http://mywebsite.com", headers: "*", methods: "*")]

        public static string GetClaimValue(this IPrincipal currentPrincipal, string key)
        {
            var identity = currentPrincipal.Identity as ClaimsIdentity;
            if (identity == null)
                return null;

            var claim = identity.Claims.FirstOrDefault(c => c.Type == key);
            return claim?.Value;
        }

        public override Task<ClaimsIdentity> CreateUserIdentityAsync(User user)
        {
            return _userManager.GenerateUserIdentityAsync(user);
        }

                case SignInStatus.Success:
                    var user = await _userManager.FindByNameAsync(model.UserName);
                    await _signInManager.CreateUserIdentityAsync(user);
                    return RedirectToLocal(returnUrl);

app.Use(async (context, next) =>
{
   context.Items["isVerified"] = true;
   await next.Invoke();
});

app.Run(async (context) =>
{
   await context.Response.WriteAsync("Verified request? " + context.Items["isVerified"]);
});

{
    "dependencies": {
      //same as before
      "Microsoft.AspNetCore.Session": "1.0.0"
    }
}

public void ConfigureServices(IServiceCollection services)
{
    services.AddSession();

public void Configure(IApplicationBuilder app)
{
    app.UseSession();

app.UseSession(options: new SessionOptions
{
    IdleTimeout = TimeSpan.FromMinutes(30),
    CookieName = ".MyApplication"
});

public ActionResult TestSession()
{
 
   this.HttpContext.Session.Set("key-1", BitConverter.GetBytes(DateTime.Now.Ticks));
   this.HttpContext.Session.SetInt32("key-2", 1);
   this.HttpContext.Session.SetString("key-3", "DNT");
 
   return Content("OK!");
}

 public IActionResult Index()
{
   byte[] key1 = this.HttpContext.Session.Get("key-1");
   long key1Value = BitConverter.ToInt64(key1, 0);
 
   int? key2Value = this.HttpContext.Session.GetInt32("key-2");
   string key3Value = this.HttpContext.Session.GetString("key-3");
 
   return Content("OK!");
}

using System;
using Microsoft.AspNetCore.Http;
using Newtonsoft.Json;
 
namespace Core1RtmEmptyTest.StartupCustomizations
{
    public static class SessionExts
    {
        public static void SetDateTime(this ISession collection, string key, DateTime value)
        {
            collection.Set(key, BitConverter.GetBytes(value.Ticks));
        }
 
        public static DateTime? GetDateTime(this ISession collection, string key)
        {
            var data = collection.Get(key);
            if (data == null)
            {
                return null;
            }
            var dateInt = BitConverter.ToInt64(data, 0);
            return new DateTime(dateInt);
        }
 
        public static void SetObject(this ISession session, string key, object value)
        {
            var stringValue = JsonConvert.SerializeObject(value);
            session.SetString(key, stringValue);
        }
 
        public static T GetObject<T>(this ISession session, string key)
        {
            var stringValue = session.GetString(key);
            return JsonConvert.DeserializeObject<T>(stringValue);
        }
    }
}

{
    "dependencies": {
     //same as before
     "Microsoft.Extensions.Configuration.Json": "1.0.0"
   }
}

public class JobSubCategoryService : IJobSubCategoryService
{ 
       private readonly Lazy<IUnitOfWork> _uow;
        private readonly Lazy<IDbSet<JobSubCategory>> _jobSubCategories;
        public JobSubCategoryService(Lazy<IUnitOfWork> uow)
        {
            _uow = uow;
            _jobSubCategories = uow.Value.Set<JobSubCategory>();  // i have problem here
        }
    
    // some methods here ...
}

public override int GetHashCode()
{
    unchecked
    {
        int hashCode = 17; 
        hashCode = (hashCode * 23) + (name == null ? 0 : this.name.GetHashCode()); 
        hashCode = (hashCode * 23) + this.age; 
        foreach (string power in this.powers)
        {
            hashCode = (hashCode * 23) + (power == null ? 0 : power.GetHashCode());
        } 
        return hashCode;
    }
}

public override int GetHashCode()
{
    var hash = new HashCode();
    hash.Add(this.object1);
    hash.Add(this.object2);
    return hash.ToHashCode();
}

    public partial class SidebarMenuController : Controller
    {
        const int Min15 = 900;

        [ChildActionOnly]
        [OutputCache(Duration = Min15)]
        public virtual ActionResult Index()
        {
            return PartialView(viewName: MVC.Shared.Views._SidebarMenu);
        }
    }

@{Html.RenderAction(result: MVC.SidebarMenu.Index());}

  <MathJax sanitizeOptions={ {USE_PROFILES: {html: true,mathMl: true}}} style={{'display':'inline-block'}} math={this.props.question.title} />