There is a myth about white text over black backgrounds being the best color contrast combination for accessibility, but in reality, white text on black backgrounds creates a visual fuzzing effect for people with astigmatism called “halation”. This effect is known to reduce text readability and is particularly bad for people with astigmatism because it can cause terrible headaches. 

These are the customer-reported issues addressed in 15.8.2:

• Publish single file context menu item missing.
• Git network operations not working: Cannot spawn git-askpass.exe.
• "Visual C++ Resource Editor Package" load failed.
• Preview Transform gives error.
• Cannot type close brace.
• Object reference not set to an instance of an object when deploying Service Fabric project after update 15.8.0.
• "The given path's format is not supported" installation error.
• Task ExpandPriContent failed. Illegal characters in path.
• "Could not create instance of type System.Collections.Genertic.Iset'1[Signer]" installer error.
• Service fabric deployment fails in 15.8.0.
• Cannot create app package for Windows store.
• Incorrect code generation for strongly-typed resources.
• Keyboard binding for Italian layout.
• IntelliSense broken #9999.
• When working on a Unity project and Unity rewrites multiple project files, the Visual Studio Tools for Unity will now automatically reload the solution.
• The customer will now get a dialog to close Office applications if they are blocking the Visual Studio install and causing a failure of 1303. 

{
    "type": "https://example.com/probs/out-of-credit",
    "title": "You do not have enough credit.",
    "detail": "Your current balance is 30, but that costs 50.",
    "instance": "/account/12345/msgs/abc",
    "status": 403,
}

var mediaType = response.Content.Headers.ContentType?.MediaType;
if (mediaType != null && mediaType.Equals("application/problem+json", StringComparison.InvariantCultureIgnoreCase))
{
   var problemDetails = await response.Content.ReadFromJsonAsync<ProblemDetails>(null, ct) ?? new ProblemDetails();
   // ...
}

[HttpPost("/sales/products/{sku}/availableForSale")]
public async Task<IActionResult> AvailableForSale([FromRoute] string sku)
{
   return Problem(
            "Product is already Available For Sale.",
            "/sales/products/1/availableForSale",
            400,
            "Cannot set product as available.",
            "http://example.com/problems/already-available");
}

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json
Content-Language: en
{
    "type": "https://tools.ietf.org/html/rfc7231#section-6.5.1",
    "title": "One or more validation errors occurred.",
    "status": 400,
    "errors": {
        "User": [
            "The user name is not verified."
        ]
    }
}

namespace WebApplication.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class DemoController : ControllerBase
    {
        [HttpPost]
        public ActionResult Post()
        {
            var problemDetails = new ProblemDetails
            {
                Detail = "The request parameters failed to validate.",
                Instance = null,
                Status = 400,
                Title = "Validation Error",
                Type = "https://example.net/validation-error",
            };

            problemDetails.Extensions.Add("invalidParams", new List<ValidationProblemDetailsParam>()
            {
                new("name", "Cannot be blank."),
                new("age", "Must be great or equals to 18.")
            });

            return new ObjectResult(problemDetails)
            {
                StatusCode = 400
            };
        }
    }

    public class ValidationProblemDetailsParam
    {
        public ValidationProblemDetailsParam(string name, string reason)
        {
            Name = name;
            Reason = reason;
        }

        public string Name { get; set; }
        public string Reason { get; set; }
    }
}

services.AddProblemDetails();

app.UseExceptionHandler();

app.UseStatusCodePages();

app.UseDeveloperExceptionPage();

builder.Services.AddProblemDetails(options =>
    options.CustomizeProblemDetails = ctx =>
            ctx.ProblemDetails.Extensions.Add("MachineName", Environment.MachineName));

public class MyErrorFeature
{
    public ErrorType Error  { get; set; }
}
​
public enum ErrorType
{
    ArgumentException
}

    [HttpGet("{value}")]
    public IActionResult MyErrorTest(int value)
    {
        if (value <= 0)
        {
            var errorType = new MyErrorFeature
            {
                Error = ErrorType.ArgumentException
            };
            HttpContext.Features.Set(errorType);
            return BadRequest();
        }
​
        return Ok(value);
    }

services.AddProblemDetails(options =>
    options.CustomizeProblemDetails = ctx =>
    {
        var MyErrorFeature = ctx.HttpContext.Features.Get<MyErrorFeature>();
​
        if (MyErrorFeature is not null)
        {
            (string Title, string Detail, string Type) details = MyErrorFeature.Error switch
            {
                ErrorType.ArgumentException =>
                (
                    nameof(ArgumentException),
                    "This is an argument-exception.",
                    "https://www.rfc-editor.org/rfc/rfc7231#section-6.5.1"
                ),
                _ =>
                (
                    nameof(Exception),
                    "default-exception",
                    "https://www.rfc-editor.org/rfc/rfc7231#section-6.6.1"
                )
            };
​
            ctx.ProblemDetails.Title = details.Title;
            ctx.ProblemDetails.Detail = details.Detail;
            ctx.ProblemDetails.Type = details.Type;
        }
    }
);

public class MyCustomException : Exception
{
    public MyCustomException(
        string message,
        HttpStatusCode statusCode = HttpStatusCode.BadRequest
    ) : base(message)
    {
        StatusCode = statusCode;
    }
​
    public HttpStatusCode StatusCode { get; }
}

    [HttpGet("{value}")]
    public IActionResult MyErrorTest(int value)
    {
        if (value <= 0)
        {
            throw new MyCustomException("The value should be positive!");
        }
​
        return Ok(value);
    }

app.UseExceptionHandler(exceptionHandlerApp =>
{
    exceptionHandlerApp.Run(async context =>
    {
        context.Response.ContentType = "application/problem+json";
​
        if (context.RequestServices.GetService<IProblemDetailsService>() is { } problemDetailsService)
        {
            var exceptionHandlerFeature = context.Features.Get<IExceptionHandlerFeature>();
            var exceptionType = exceptionHandlerFeature?.Error;
​
            if (exceptionType is not null)
            {
                (string Title, string Detail, string Type, int StatusCode) details = exceptionType switch
                {
                    MyCustomException MyCustomException =>
                    (
                        exceptionType.GetType().Name,
                        exceptionType.Message,
                        "https://www.rfc-editor.org/rfc/rfc7231#section-6.5.1",
                        context.Response.StatusCode = (int)MyCustomException.StatusCode
                    ),
                    _ =>
                    (
                        exceptionType.GetType().Name,
                        exceptionType.Message,
                        "https://www.rfc-editor.org/rfc/rfc7231#section-6.6.1",
                        context.Response.StatusCode = StatusCodes.Status500InternalServerError
                    )
                };
​
                await problemDetailsService.WriteAsync(new ProblemDetailsContext
                {
                    HttpContext = context,
                    ProblemDetails =
                    {
                        Title = details.Title,
                        Detail = details.Detail,
                        Type = details.Type,
                        Status = details.StatusCode
                    }
                });
            }
        }
    });
});
​

  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
  <Import Project="..\packages\PostSharp.2.1.7.30\tools\PostSharp.targets" 
    Condition="Exists('..\packages\PostSharp.2.1.7.30\tools\PostSharp.targets')" />

در کروم:

برای رفع این مشکل فقط کافی است دو دستور زیر را با دسترسی مدیریتی اجرا کنید:

dotnet dev-certs https --clean
dotnet dev-certs https --trust

Based on the above observations, we can conclude that React will be the best framework to learn in 2021, followed by Vue. But there is a high chance of Angular defending second place since it has been there for a longer period of time than Vue, and surely 2021 is not the end of that. So if you are an Angular developer, I suggest you learn React in the upcoming days.

In this post, we are going to write about what we consider to be the best practices while developing the .NET Core Web API project. How we can make it better and how to make it more maintainable.

We are going to go through the following sections:

• Startup Class and the Service Configuration
• Project Organization
• Environment Based Settings
• Data Access Layer
• Controllers
• Actions
• Microsoft.AspNetCore.All Meta-Package
• Routing
• Logging
• CryptoHelper
• Content Negotiation
• Using JWT
• Conclusion  

    public class User
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public virtual ICollection<BlogPost> BlogPosts { get; set; }
    }

    public class BlogPost
    {
        public int Id { get; set; }
        public string Title { get; set; }
        public string Content { get; set; }

        [ForeignKey("UserId")]
        public virtual User User { get; set; }
        public int UserId { get; set; }
    }

 var data = context.BlogPosts.ToList();

 var data = context.BlogPosts.ToList();

 var list = context.BlogPosts.Select(x => x.Content).Skip(15).Take(15).ToList();

 foreach (var post in context.BlogPosts)
{
     Console.WriteLine(post.User.Name);
}

 foreach (var post in context.BlogPosts.Include(x=>x.User))

 var data = context.BlogPosts.ToList();

 var data = context.BlogPosts.AsNoTracking().Skip(15).Take(15).ToList();

        private void problem5MoreThan1ConnectionPerRequest() 
        {
            using (var context = new MyContext())
            {
                var count = context.BlogPosts.ToList();
            }
        }

DataContext = from user in context.Users
                      where user.Id>10
                      select user;

 var list = context.BlogPosts.Where(x => x.Content.Contains("test"))