C# 7 introduced pattern matching with the extension of the switch statement and the is operator offering the const pattern, the type pattern, and the var pattern. With C# 8 an extension of pattern matching is planned, including the property pattern, the recursive pattern, and a new switch – the switch expression.
These are the customer-reported issues addressed in this release:
- The debugger cannot continue running the process. Operation not supported. Unknown error: 0x9233000b.
- Recent Projects and Solutions not populated once executed.
- Full build every time with 15.5.
- Wrong IntelliSense errors are still shown on VS 15.5.2 for Visual Basic projects.
- VS2017 15.5.2 Unresolved references when "Allow parallel project initialization" is enabled.
- Upgrading to 15.5.2: cannot launch nor repair VS.
- VS2017 Installation issue.
- Unable to install because of BSoD.
روال کار به این صورت بوده که قبل از رندر شدن صفحه در سمت سرور خروجی نهایی بررسی شده و با استفاده از عبارات با قاعده الگوهای مورد نظر لیست شده و سپس حذف میشوند و در نهایت خروجی مورد نظر حاصل خواهد شد. برای راحتی کار و عدم نوشتن این روال در تمامی صفحات میتواند در مستر پیج این عمل را انجام داد. مثلا:
private static readonly Regex RegexBetweenTags = new Regex(@">\s+<", RegexOptions.Compiled); private static readonly Regex RegexLineBreaks = new Regex(@"\r\s+", RegexOptions.Compiled); protected override void Render(HtmlTextWriter writer) { using (var htmlwriter = new HtmlTextWriter(new System.IO.StringWriter())) { base.Render(htmlwriter); var html = htmlwriter.InnerWriter.ToString(); html = RegexBetweenTags.Replace(html, "> <"); html = RegexLineBreaks.Replace(html, string.Empty); html = html.Replace("//<![CDATA[", "").Replace("//]]>", ""); html = html.Replace("// <![CDATA[", "").Replace("// ]]>", ""); writer.Write(html.Trim()); } }
این عمل در ASP.NET Webform به آسانی انجام شده و باعث حذف فضاهای خالی در خروجی صفحه میشود.
برای انجام این عمل در ASP.NET MVC روال کار به این صورت نیست و نمیتوان مانند ASP.NET Webform عمل کرد.
چون در MVC از ViewPage استفاده میشود و ما مستقیما به خروجی آن دسترسی نداریم یک روش این است که میتوانیم یک کلاس برای ViewPage تعریف کرده و رویداد Write آن را تحریف کرده و مانند مثال بالا فضای خالی را در خروجی حذف کرد. البته برای استفاده باید کلاس ایجاد شده را به عنوان فایل پایه جهت ایجاد صفحات در MVC فایل web.config معرفی کنیم. این روش در اینجا به وضوح شرح داده شده است.
اما هدف ما پیاده سازی با استفاده از اکشن فیلتر هاست. برای پیاده سازی ایتدا یک اکشن فیلتر به نام CompressAttribute تعریف میکنیم مانند زیر:
using System; using System.IO; using System.IO.Compression; using System.Text; using System.Text.RegularExpressions; using System.Web; using System.Web.Mvc; namespace PWS.Common.ActionFilters { public class CompressAttribute : ActionFilterAttribute { #region Methods (2) // Public Methods (1) /// <summary> /// Called by the ASP.NET MVC framework before the action method executes. /// </summary> /// <param name="filterContext">The filter context.</param> public override void OnActionExecuting(ActionExecutingContext filterContext) { var response = filterContext.HttpContext.Response; if (IsGZipSupported(filterContext.HttpContext.Request)) { String acceptEncoding = filterContext.HttpContext.Request.Headers["Accept-Encoding"]; if (acceptEncoding.Contains("gzip")) { response.Filter = new GZipStream(response.Filter, CompressionMode.Compress); response.AppendHeader("Content-Encoding", "gzip"); } else { response.Filter = new DeflateStream(response.Filter, CompressionMode.Compress); response.AppendHeader("Content-Encoding", "deflate"); } } // Allow proxy servers to cache encoded and unencoded versions separately response.AppendHeader("Vary", "Content-Encoding"); //حذف فضاهای خالی
response.Filter = new WhitespaceFilter(response.Filter); } // Private Methods (1) /// <summary> /// Determines whether [is G zip supported] [the specified request]. /// </summary> /// <param name="request">The request.</param> /// <returns></returns> private Boolean IsGZipSupported(HttpRequestBase request) { String acceptEncoding = request.Headers["Accept-Encoding"]; if (acceptEncoding == null) return false; return !String.IsNullOrEmpty(acceptEncoding) && acceptEncoding.Contains("gzip") || acceptEncoding.Contains("deflate"); } #endregion Methods } /// <summary> /// Whitespace Filter /// </summary> public class WhitespaceFilter : Stream { #region Fields (3) private readonly Stream _filter; /// <summary> /// /// </summary> private static readonly Regex RegexAll = new Regex(@"\s+|\t\s+|\n\s+|\r\s+", RegexOptions.Compiled); /// <summary> /// /// </summary> private static readonly Regex RegexTags = new Regex(@">\s+<", RegexOptions.Compiled); #endregion Fields #region Constructors (1) /// <summary> /// Initializes a new instance of the <see cref="WhitespaceFilter" /> class. /// </summary> /// <param name="filter">The filter.</param> public WhitespaceFilter(Stream filter) { _filter = filter; } #endregion Constructors #region Properties (5) //methods that need to be overridden from stream /// <summary> /// When overridden in a derived class, gets a value indicating whether the current stream supports reading. /// </summary> /// <returns>true if the stream supports reading; otherwise, false.</returns> public override bool CanRead { get { return true; } } /// <summary> /// When overridden in a derived class, gets a value indicating whether the current stream supports seeking. /// </summary> /// <returns>true if the stream supports seeking; otherwise, false.</returns> public override bool CanSeek { get { return true; } } /// <summary> /// When overridden in a derived class, gets a value indicating whether the current stream supports writing. /// </summary> /// <returns>true if the stream supports writing; otherwise, false.</returns> public override bool CanWrite { get { return true; } } /// <summary> /// When overridden in a derived class, gets the length in bytes of the stream. /// </summary> /// <returns>A long value representing the length of the stream in bytes.</returns> public override long Length { get { return 0; } } /// <summary> /// When overridden in a derived class, gets or sets the position within the current stream. /// </summary> /// <returns>The current position within the stream.</returns> public override long Position { get; set; } #endregion Properties #region Methods (6) // Public Methods (6) /// <summary> /// Closes the current stream and releases any resources (such as sockets and file handles) associated with the current stream. Instead of calling this method, ensure that the stream is properly disposed. /// </summary> public override void Close() { _filter.Close(); } /// <summary> /// When overridden in a derived class, clears all buffers for this stream and causes any buffered data to be written to the underlying device. /// </summary> public override void Flush() { _filter.Flush(); } /// <summary> /// When overridden in a derived class, reads a sequence of bytes from the current stream and advances the position within the stream by the number of bytes read. /// </summary> /// <param name="buffer">An array of bytes. When this method returns, the buffer contains the specified byte array with the values between <paramref name="offset" /> and (<paramref name="offset" /> + <paramref name="count" /> - 1) replaced by the bytes read from the current source.</param> /// <param name="offset">The zero-based byte offset in <paramref name="buffer" /> at which to begin storing the data read from the current stream.</param> /// <param name="count">The maximum number of bytes to be read from the current stream.</param> /// <returns> /// The total number of bytes read into the buffer. This can be less than the number of bytes requested if that many bytes are not currently available, or zero (0) if the end of the stream has been reached. /// </returns> public override int Read(byte[] buffer, int offset, int count) { return _filter.Read(buffer, offset, count); } /// <summary> /// When overridden in a derived class, sets the position within the current stream. /// </summary> /// <param name="offset">A byte offset relative to the <paramref name="origin" /> parameter.</param> /// <param name="origin">A value of type <see cref="T:System.IO.SeekOrigin" /> indicating the reference point used to obtain the new position.</param> /// <returns> /// The new position within the current stream. /// </returns> public override long Seek(long offset, SeekOrigin origin) { return _filter.Seek(offset, origin); } /// <summary> /// When overridden in a derived class, sets the length of the current stream. /// </summary> /// <param name="value">The desired length of the current stream in bytes.</param> public override void SetLength(long value) { _filter.SetLength(value); } /// <summary> /// When overridden in a derived class, writes a sequence of bytes to the current stream and advances the current position within this stream by the number of bytes written. /// </summary> /// <param name="buffer">An array of bytes. This method copies <paramref name="count" /> bytes from <paramref name="buffer" /> to the current stream.</param> /// <param name="offset">The zero-based byte offset in <paramref name="buffer" /> at which to begin copying bytes to the current stream.</param> /// <param name="count">The number of bytes to be written to the current stream.</param> public override void Write(byte[] buffer, int offset, int count) { string html = Encoding.Default.GetString(buffer); //remove whitespace html = RegexTags.Replace(html, "> <"); html = RegexAll.Replace(html, " "); byte[] outdata = Encoding.Default.GetBytes(html); //write bytes to stream _filter.Write(outdata, 0, outdata.GetLength(0)); } #endregion Methods } }
در کلاس WhitespaceFilter با تحریف متد Write الگوهای فضای خالی موجود در درخواست یافت شده و آنها را حذف میکنیم. در نهایت خروجی این کلاس که از نوع استریم است به ویژگی فیلتر صفحه اعمال میشود.
برای معرفی فیلتر تعریف شده میتوان در فایل Global.asax در رویداد Application_Start به صورت زیر فیلتر مورد نظر را به فیلترهای MVC اعمال کرد.
GlobalFilters.Filters.Add(new CompressAttribute());
پ.ن: جهت سهولت، در این کلاس ها، صفحات فشرده سازی و همزمان فضاهای خالی آنها حذف شده است.
The Problem
What they neglect to say is all that testability and persistence ignorance flies right out the window when you create a new ASP.NET Web Application using the MVC template and "Individual User Accounts" authentication. What you get is a single-layered application, tightly coupled to Entity Framework, that:
-
Ignores the patterns that facilitate testing, including: the repository pattern, unit of work pattern, and dependency injection;
-
Forces you to implement their
IUser
interface in your application’s User entity, thereby coupling it to ASP.NET Identity; -
Eliminates any clear separation between your entities, persistence concerns, and business logic. Persistence ignorance? Forget about it.
Thankfully, due to the extensibility designed into ASP.NET Identity, it is possible to ditch the reference to the Microsoft.AspNet.Identity.EntityFramework
assembly and write a custom implementation that can address these and other architectural issues. Just be forewarned: it is not a trivial undertaking, and you’ll have to put up with some code smell that is baked into the Microsoft.AspNet.Identity.Core
assembly.
WebStorm 2019.1.1 منتشر شد
معرفی NET Community Toolkit.
Response Caching در ASP.NET Core 1.1
With the ASP.NET Core 1.1 release, many new features were introduced. One of them was enabling gZip compression and today we will take a look at another new feature which is Response Caching Middleware.
Here are some of the reasons why nullable reference types are less than ideal:
- Invoking a member on a null value will issue a System.NullReferenceException exception, and every invocation that results in a System.NullReferenceException in production code is a bug. Unfortunately, however, with nullable reference types we “fall in” to doing the wrong thing rather than the right thing. The “fall in” action is to invoke a reference type without checking for null.
- There’s an inconsistency between reference types and value types (following the introduction of Nullable<T>) in that value types are nullable when decorated with “?” (for example, int? number); otherwise, they default to non-nullable. In contrast, reference types are nullable by default. This is “normal” to those of us who have been programming in C# for a long time, but if we could do it all over, we’d want the default for reference types to be non-nullable and the addition of a “?” to be an explicit way to allow nulls.
- It’s not possible to run static flow analysis to check all paths regarding whether a value will be null before dereferencing it, or not. Consider, for example, if there were unmanaged code invocations, multi-threading, or null assignment/replacement based on runtime conditions. (Not to mention whether analysis would include checking of all library APIs that are invoked.)
- There’s no reasonable syntax to indicate that a reference type value of null is invalid for a particular declaration.
- There’s no way to decorate parameters to not allow null.