In Web Api it contains some special flags: http://www.strathweb.com/2013/08/asp-net-web-api-2-and-httprequestcontext/

For example, IncludeErrorDetail, IsLocal, ClientCertificate are stored in the dictionary, but have properties for easy access.

I found this statement from [THOMAS LEVESQUE&#39;S .NET BLOG][1] which is how I was hoping to use it. MS or other places don&#39;t really describe it correctly... that we can use it however we want to carry per request information.  In my case, store information about the destination so that I can validate the certificate per destination.


&gt; Let&#39;s see how we can associate a timeout value to a request. The
&gt; HttpRequestMessage class has a Properties property, which is a
&gt; dictionary in which we can put whatever we need. We&#39;re going to use
&gt; this to store the timeout for a request, and to make things easier,
&gt; we&#39;ll create extension methods to access the value in a strongly-typed
&gt; fashion:

  [1]: https://thomaslevesque.com/2018/02/25/better-timeout-handling-with-httpclient/

How to change text color of menu item title. I tried to change it as below

    &lt;style name=&quot;Theme.Kanku.ActionBar.TitleTextStyle&quot; parent=&quot;@android:style/TextAppearance.Holo.Widget.ActionBar.Title&quot;&gt;
	    &lt;item name=&quot;android:textColor&quot;&gt;@color/white&lt;/item&gt;
    &lt;/style&gt;
But it change color only of Action Bar title text, but not menu item text.

Action Bar menu item text color

Apparently in my last question I demonstrated confusion between `data.frame` and `data.table`.  Admittedly, I didn&#39;t realize there was a distinction.  

So I read the help for each but in practical, everyday terms, what is the difference, what are the implications and what are each used for that would help guide me to their appropriate usage?

What is the practical difference between data.frame and data.table in R

What is the purpose of [**HttpRequestMessage.Properties**][1]?

I&#39;m wondering if it provides something useful for my application.


  [1]: http://msdn.microsoft.com/en-us/library/system.net.http.httprequestmessage.properties.aspx

What is HttpRequestMessage.Properties?

What is the purpose of <a href="http://msdn.microsoft.com/en-us/library/system.net.http.httprequestmessage.properties.aspx" target="_blank" rel="noopener noreferrer">HttpRequestMessage.Properties</a>?
I'm wondering if it provides something useful for my application.

I would like to ask you on your opinion about the correct architecture when to use `Task.Run`. I am experiencing laggy UI in our WPF .NET 4.5
application (with Caliburn Micro framework).

Basically I am doing (very simplified code snippets):

    public class PageViewModel : IHandle&lt;SomeMessage&gt;
    {
       ...

       public async void Handle(SomeMessage message)
       {
          ShowLoadingAnimation();

          // Makes UI very laggy, but still not dead
          await this.contentLoader.LoadContentAsync();

          HideLoadingAnimation();
       }
    }

    public class ContentLoader
    {
        public async Task LoadContentAsync()
        {
            await DoCpuBoundWorkAsync();
            await DoIoBoundWorkAsync();
            await DoCpuBoundWorkAsync();

            // I am not really sure what all I can consider as CPU bound as slowing down the UI
            await DoSomeOtherWorkAsync();
        }
    }

From the articles/videos I read/saw, I know that `await` `async` is not necessarily running on a background thread and to start work in the background you need to wrap it with await `Task.Run(async () =&gt; ... )`. Using `async` `await` does not block the UI, but still it is running on the UI thread, so it is making it laggy.

Where is the best place to put Task.Run?

Should I just

1. Wrap the outer call because this is less threading work for .NET

2. , or should I wrap only CPU-bound methods internally running with `Task.Run` as this makes it reusable for other places? I am not sure here if starting work on background threads deep in core is a good idea.

Ad (1), the first solution would be like this:

    public async void Handle(SomeMessage message)
    {
        ShowLoadingAnimation();
        await Task.Run(async () =&gt; await this.contentLoader.LoadContentAsync());
        HideLoadingAnimation();
    }

    // Other methods do not use Task.Run as everything regardless
    // if I/O or CPU bound would now run in the background.

Ad (2), the second solution would be like this:

    public async Task DoCpuBoundWorkAsync()
    {
        await Task.Run(() =&gt; {
            // Do lot of work here
        });
    }

    public async Task DoSomeOtherWorkAsync(
    {
        // I am not sure how to handle this methods -
        // probably need to test one by one, if it is slowing down UI
    }


When correctly use Task.Run and when just async-await


    Type t = typeof(int?); //will get this dynamically
    object val = 5; //will get this dynamically
    object nVal = Convert.ChangeType(val, t);//getting exception here


I am getting InvalidCastException in above code. For above I could simply write `int? nVal = val`, but above code is executing dynamically. 

I am getting a value(of non nullable type like int, float, etc) wrapped up in an object (here val), and I have to save it to another object by casting it to another type(which can or cannot be nullable version of it). When 

&gt; Invalid cast from &#39;System.Int32&#39; to &#39;System.Nullable`1[[System.Int32,
&gt; mscorlib, Version=4.0.0.0, Culture=neutral,
&gt; PublicKeyToken=b77a5c561934e089]]&#39;.

An `int`, should be convertible/type-castable to `nullable int`, what is the issue here ?

Invalid cast from &#39;System.Int32&#39; to &#39;System.Nullable`1[[System.Int32, mscorlib]]

This is something I discovered just a few days ago, I got confirmation that it isn&#39;t just limited to my machine from [this question][1].

The easiest way to repro it is by starting a Windows Forms application, add a button and write this code:

        private void button1_Click(object sender, EventArgs e) {
            MessageBox.Show(&quot;yada&quot;);
            Environment.Exit(1);         // Kaboom!
        }

The program fails *after* the Exit() statement executes. On Windows Forms  you get &quot;Error creating window handle&quot;.

Enabling unmanaged debugging makes it somewhat clear what&#39;s going on. The [COM][2] modal loop is executing and allows a WM_PAINT message to be delivered. That&#39;s fatal on a disposed form.

The only facts I&#39;ve gathered so far are:

 - It isn&#39;t just limited to running with the debugger.  This also fails without one.  Rather poorly as well, the WER crash dialog shows up *twice*.
 - It doesn&#39;t have anything to do with the bitness of the process. The wow64 layer is pretty notorious, but an AnyCPU build crashes the same way.
 - It doesn&#39;t have anything to do with the .NET version, 4.5 and 3.5 crash the same way.
 - The exit code doesn&#39;t matter.
 - Calling Thread.Sleep() before calling Exit() doesn&#39;t fix it.
 - This happens on the 64-bit version of Windows 8, and Windows 7 does not seem to be affected the same way.
 - This should be relatively new behavior, I haven&#39;t seen this before.  I see no relevant updates delivered through [Windows Update][3], albeit that the update history isn&#39;t accurate on my machine any more.
 - This is grossly breaking behavior. You would write code like this in an event handler for AppDomain.UnhandledException, and it crashes the same way.

I&#39;m particularly interested in what you could possibly do to avoid this crash.  Particularly the AppDomain.UnhandledException scenario stumps me; there are not a lot of ways to terminate a .NET program.  Please do note that calling Application.Exit() or Form.Close() are not valid in an event handler for UnhandledException, so they are not workarounds.


----------
UPDATE: Mehrdad pointed out that the finalizer thread could be part of the problem.  I think I&#39;m seeing this and am also seeing some evidence for the 2 second timeout that the CLR gives the finalizer thread to finish executing.

The finalizer is inside NativeWindow.ForceExitMessageLoop().  There&#39;s an IsWindow() Win32 function there that roughly corresponds with the code location, offset 0x3c when looking at the machine code in 32-bit mode.  It seems that IsWindow() is deadlocking.  I cannot get a good stack trace for the internals however, the debugger thinks the [P/Invoke][4] call just returned.  This is hard to explain.  If you can get a better stack trace then I&#39;d love to see it.  Mine:

    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.ForceExitMessageLoop() + 0x3c bytes
    System.Windows.Forms.dll!System.Windows.Forms.NativeWindow.Finalize() + 0x16 bytes
    [Native to Managed Transition]
    kernel32.dll!@BaseThreadInitThunk@12()  + 0xe bytes
    ntdll.dll!___RtlUserThreadStart@8()  + 0x27 bytes
    ntdll.dll!__RtlUserThreadStart@8()  + 0x1b bytes

Nothing above the ForceExitMessageLoop call, unmanaged debugger enabled.

  [1]: https://stackoverflow.com/questions/18036216/win32exception-was-unhandled-visual-basic-when-click-on-exit-button?noredirect=1#comment26385195_18036216
  [2]: http://en.wikipedia.org/wiki/Component_Object_Model
  [3]: http://en.wikipedia.org/wiki/Windows_Update
  [4]: http://en.wikipedia.org/wiki/Platform_Invocation_Services


Why does Environment.Exit() not terminate the program any more?

I have had endless issues with stored procedures and EDMX. I created a procedure, updated the model from the database, and all worked. I then removed a column and added a new one in the stored procedure. I updated the model, but the EDMX didn&#39;t seem to refresh the proc definition.

I dropped the proc, and did an update, but manually had to delete all references to the proc. I ended up just renaming the proc and importing via model update from database.

I just had the same issue. Added a new column, and renamed an existing column. I refreshed the EDMX via update model from database, but there were no changes to the EDMX, and obviously at run time, it fails. How should a stored procedure update be done with Entity Framework?

![enter image description here][1]


  [1]: http://i.stack.imgur.com/UelyM.png

I removed the proc, regenerated the model, deleted the &#39;cs&#39; files for the proc, compiled, then added the procedure to the database again, regenerated the model, and bang! It adds the same model 3 times, with only the last one being right. Why does it keep bringing back the old versions?

Stored Procedures and updating EDMX

I lost the solution of class-library, can I open `.dll` file which is created by `class-library`.  

How to open .dll files to see what is written inside?

I have the following code:

    public static async Task&lt;string&gt; Start(IProgress&lt;ProcessTaskAsyncExProgress&gt; progress)
    {
        const int total = 10;
        for (var i = 0; i &lt;= total; i++)
        {
            await Task.Run(() =&gt; RunLongTask(i.ToString(CultureInfo.InvariantCulture)));
            if (progress != null)
            {
                var args = new ProcessTaskAsyncExProgress
                {
                    ProgressPercentage = (int)(i / (double)total * 100.0),
                    Text = &quot;processing &quot; + i
                };
                progress.Report(args);
            }
        }
        return &quot;Done&quot;;
    }

    private static string RunLongTask(string taskName)
    {
        Task.Delay(300);
        return taskName + &quot;Completed!&quot;;
    }


How do I get back the string value of `RunLongTask` from this line: `await Task.Run(() =&gt; RunLongTask(i.ToString(CultureInfo.InvariantCulture)));`?

I&#39;ve tried:

    var val = await Task.Run(() =&gt; RunLongTask(i.ToString(CultureInfo.InvariantCulture))).Result;

But I get an error saying &quot;string is not awaitable&quot;.

Getting return value from Task.Run

In the book Programming C#, it has some sample code about `SynchronizationContext`:

    SynchronizationContext originalContext = SynchronizationContext.Current;
    ThreadPool.QueueUserWorkItem(delegate {
        string text = File.ReadAllText(@&quot;c:\temp\log.txt&quot;);
        originalContext.Post(delegate {
            myTextBox.Text = text;
        }, null);
    });

I&#39;m a beginner in threads, so please answer in detail.
First, I don&#39;t know what does context mean, what does the program save in the `originalContext`?  And when the `Post` method is fired, what will the UI thread do?  
If I ask some silly things, please correct me, thanks!

EDIT: For example, what if I just write `myTextBox.Text = text;` in the method, what&#39;s the difference?

What does SynchronizationContext do?

    public static async Task&lt;string&gt; GetData(string url, string data)
    {
        UriBuilder fullUri = new UriBuilder(url);

        if (!string.IsNullOrEmpty(data))
            fullUri.Query = data;

        HttpClient client = new HttpClient();

        HttpResponseMessage response = await client.PostAsync(new Uri(url), /*expects HttpContent*/);

        response.Content.Headers.ContentType = new MediaTypeHeaderValue(&quot;application/json&quot;);
        response.EnsureSuccessStatusCode();
        string responseBody = await response.Content.ReadAsStringAsync();

        return responseBody;
    }

The `PostAsync` takes another parameter that needs to be `HttpContent`.

How do I set up an `HttpContent`? There Is no documentation anywhere that works for Windows Phone 8.

If I do `GetAsync`, it works great! but it needs to be POST with the content of key=&quot;bla&quot;, something=&quot;yay&quot;

**//EDIT**

Thanks so much for the answer... This works well, but still a few unsures here:


        public static async Task&lt;string&gt; GetData(string url, string data)
        {
            data = &quot;test=something&quot;;

            HttpClient client = new HttpClient();
            StringContent queryString = new StringContent(data);

            HttpResponseMessage response = await client.PostAsync(new Uri(url), queryString );

            //response.Content.Headers.ContentType = new MediaTypeHeaderValue(&quot;application/json&quot;);
            response.EnsureSuccessStatusCode();
            string responseBody = await response.Content.ReadAsStringAsync();

            return responseBody;
        }

The data &quot;test=something&quot; I assumed would pick up on the api side as post data &quot;test&quot;, evidently it does not. On another matter, I may need to post entire objects/arrays through post data, so I assume json will be best to do so. Any thoughts on how I get post data through?

Perhaps something like:

    class SomeSubData
    {
        public string line1 { get; set; }
        public string line2 { get; set; }
    }
    
    class PostData
    {
        public string test { get; set; }
        public SomeSubData lines { get; set; }
    }
    
    PostData data = new PostData { 
        test = &quot;something&quot;,
        lines = new SomeSubData {
            line1 = &quot;a line&quot;,
            line2 = &quot;a second line&quot;
        }
    }
    StringContent queryString = new StringContent(data); // But obviously that won&#39;t work

How do I set up HttpContent for my HttpClient PostAsync second parameter?

I am curious what is the purpose of the [`HttpClientFactory` class](http://msdn.microsoft.com/en-us/library/system.net.http.httpclientfactory(v=vs.108).aspx). There is no description of why it exists on MSDN (see link).

There are [`Create` methods](http://msdn.microsoft.com/en-us/library/system.net.http.httpclientfactory.create(v=vs.108).aspx) with more specialized arguments, but mostly I wonder what is the difference between the call with no parameters and the normal constructor.

---
&lt;!-- language: lang-cs --&gt;

    var httpClient = HttpClientFactory.Create();

VS

&lt;!-- language: lang-cs --&gt;

    var httpClient = new HttpClient();

---

In most examples I see the use of `new HttpClient()`, without any `using` statements, even though the [`HttpClient` class](http://msdn.microsoft.com/en-us/library/system.net.http.httpclient(v=vs.110).aspx) derives from `IDisposable`.

Since the `HttpClient` class derives from `IDisposable`, is there some pooling or caching done by the factory? Are there performance benefits, or does it not matter? 

## Update –&#160;`IHttpClientFactory` in .NET Core 2.1

Please note that since this question was asked, newer versions of .NET have been released, and .NET Core 2.1 introduced a new and much improved approach for getting a HTTP client.

Refer to Ali Bayat&#39;s answer below for using `IHttpClientFactory` instead with .NET Core.

However, I&#39;m keeping Darrel Miller&#39;s answer as the accepted answer since this is the correct answer for usage in .NET Framework up to v4.8, for which this question was asked.

With .NET 5 the discrepancy between .NET Framework and .NET Core will be aligned, and you should use `IHttpClientFactory` instead.

HttpClientFactory.Create vs new HttpClient

I am trying to call a web API from my web application. I am using .Net 4.5 and while writing the code I am getting the error `HttpClient` does not contain a definition `PostAsJsonAsync` method.

Below is the code:

    HttpClient client = new HttpClient();
    client.BaseAddress = new Uri(&quot;http://localhost:51093/&quot;);
    client.DefaultRequestHeaders.Accept.Add(
       new MediaTypeWithQualityHeaderValue(&quot;application/json&quot;));
    var user = new Users();
    user.AgentCode = 100;
    user.Remarks = &quot;Test&quot;;
    user.CollectionDate = System.DateTime.Today;
    user.RemittanceDate = System.DateTime.Today;
    user.TotalAmount = 1000;
    user.OrgBranchID = 101;
            
    var response = client.PostAsJsonAsync(&quot;api/AgentCollection&quot;, user).Result;

and I am getting the error message: 

&gt; Error:  &#39;System.Net.Http.HttpClient&#39; does not contain a definition for
&gt; &#39;PostAsJsonAsync&#39; and No extension method &#39;PostAsJsonAsync&#39; accepting a first argument of
&gt; type     &#39;System.Net.Http.HttpClient&#39; could be found (are you missing
&gt; a using directive or an assembly reference?)

Please have a look  and advice me.



HttpClient not supporting PostAsJsonAsync method C#

I am building a function that given an HttpContent Object, will issues request and retry on failure.  However I get exceptions saying that HttpContent Object is disposed after issuing the request.  Is there anyway to copy or duplicate the HttpContent Object so that I can issue multiple requests.

     public HttpResponseMessage ExecuteWithRetry(string url, HttpContent content)
     {
      HttpResponseMessage result = null;
      bool success = false;
      do
      {
          using (var client = new HttpClient())
          {
              result = client.PostAsync(url, content).Result;
              success = result.IsSuccessStatusCode;
          }
      }
      while (!success);
  
     return result;
    } 

    // Works with no exception if first request is successful
    ExecuteWithRetry(&quot;http://www.requestb.in/xfxcva&quot; /*valid url*/, new StringContent(&quot;Hello World&quot;));
    // Throws if request has to be retried ...
    ExecuteWithRetry(&quot;http://www.requestb.in/badurl&quot; /*invalid url*/, new StringContent(&quot;Hello World&quot;));


(Obviously I don&#39;t try indefinitely but the code above is essentially what i want).

It yields this exception

    System.AggregateException: One or more errors occurred. ---&gt; System.ObjectDisposedException: Cannot access a disposed object.
    Object name: &#39;System.Net.Http.StringContent&#39;.
       at System.Net.Http.HttpContent.CheckDisposed()
       at System.Net.Http.HttpContent.CopyToAsync(Stream stream, TransportContext context)
       at System.Net.Http.HttpClientHandler.GetRequestStreamCallback(IAsyncResult ar)
       --- End of inner exception stack trace ---
       at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
       at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
       at System.Threading.Tasks.Task`1.get_Result()
       at Submission#8.ExecuteWithRetry(String url, HttpContent content)

Is there anyway to duplicate an HttpContent Object or reuse it?


Retrying HttpClient Unsuccessful Requests

I have got [this][1] HttpClient from Nuget.

When I want to get data I do it this way:

    var response = await httpClient.GetAsync(url);
    var data = await response.Content.ReadAsStringAsync();

But the problem is that I don&#39;t know how to post data?
I have to send a post request and send these values inside it: `comment=&quot;hello world&quot;` and `questionId = 1`. these can be a class&#39;s properties, I don&#39;t know.

**Update** I don&#39;t know how to add those values to `HttpContent` as post method needs it. `httClient.Post(string, HttpContent);` 

  [1]: http://www.nuget.org/packages/Microsoft.Net.Http

Content Type	Original Author	Original Content on Stackoverflow
Question	Drahcir	View Question on Stackoverflow
Solution 1 - C#	Der_Meister	View Answer on Stackoverflow
Solution 2 - C#	T Brown	View Answer on Stackoverflow

What is HttpRequestMessage.Properties?

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

What is the practical difference between data.frame and data.table in R

Action Bar menu item text color

Attributions