As others have commented it depend on what you are calling with HttpClient. I get what you meant though and so here are some exceptions thrown with typical method calls.

**`SendAsync`** can throw:

 - **ArgumentNullException** The request was null.
 - **InvalidOperationException** The request message was already sent by the HttpClient instance.
 - **HttpRequestException** The request failed due to an underlying issue such as network connectivity, DNS failure, server certificate
   validation or timeout.
 - **TaskCanceledException** [The request timed-out or the user canceled the request&#39;s `Task`][1].

Source: [Microsoft Docs -&gt; HttpClient -&gt; SendAsync][2]

Similarly **`GetAsync` `PostAsync` `PutAsync` `GetStringAsync` `GetStreamAsync`** etc can throw **`ArgumentNullException`**, **`HttpRequestException`** and  as above (but not `InvalidOperationException`).

Source: [Microsoft Docs -&gt; HttpClient -&gt; GetAsync][3]

Once you have called `SendAsync` or `GetAsync` etc you will have a `Task&lt;HttpResponseMessage&gt;`. Once awaited I tend to call `EnsureSuccessStatusCode()` to throw a **`HttpRequestException`** if there is a non success HTTP status code returned. https://github.com/dotnet/corefx/blob/master/src/System.Net.Http/src/System/Net/Http/HttpResponseMessage.cs#L161


  [1]: https://stackoverflow.com/questions/10547895/how-can-i-tell-when-httpclient-has-timed-out/12901496#12901496
  [2]: https://docs.microsoft.com/en-us/dotnet/api/system.net.http.httpclient.sendasync#System_Net_Http_HttpClient_SendAsync_System_Net_Http_HttpRequestMessage_
  [3]: https://docs.microsoft.com/en-us/dotnet/api/system.net.http.httpclient.getasync#System_Net_Http_HttpClient_GetAsync_System_String_

I&#39;m looking for the angular 2 way to do [this][1].

I simply have a list of items, and I want to make an input whos job is to filter the list.

    &lt;md-input placeholder=&quot;Item name...&quot; [(ngModel)]=&quot;name&quot;&gt;&lt;/md-input&gt;
    
    &lt;div *ngFor=&quot;let item of items&quot;&gt;
    {{item.name}}
    &lt;/div&gt;

What&#39;s the actual way of doing this in Angular 2? Does that requires a pipe?

  [1]: http://www.w3schools.com/howto/howto_js_filter_lists.asp

Angular 2 filter/search list

I noticed that string literals have very different addresses in memory than other constants and variables (Linux OS): they have many leading zeroes (not printed).

Example:
   
    const char *h = &quot;Hi&quot;;
    int i = 1;
    printf (&quot;%p\n&quot;, (void *) h);
    printf (&quot;%p\n&quot;, (void *) &amp;i);
    
Output:

    0x400634
    0x7fffc1ef1a4c

I know they are stored in the `.rodata` part of the executable. Is there a special way the OS handles it afterwards, so the literals end up in a special area of memory (with leading zeroes)? Are there any advantages of that memory location or is there something special about it?

Why are the memory addresses of string literals so different from others&#39;, on Linux?

I am using [HttpClient](https://msdn.microsoft.com/de-de/library/system.net.http.httpclient(v=vs.118).aspx) in a xamarin forms project

The class is documented, but I can not find any documentation about which exceptions its methods might throw.

For example the [GetAsync](https://msdn.microsoft.com/de-de/library/hh158944(v=vs.118).aspx) Method does not have any documentation about possible exceptions. But I assume it throws, for example when the server is unreachable.

Is there somewhere a list of exceptions this class might throw?

Which exceptions can HttpClient throw?

I am using <a href="https://msdn.microsoft.com/de-de/library/system.net.http.httpclient(v=vs.118).aspx" target="_blank" rel="noopener noreferrer">HttpClient</a> in a xamarin forms project
The class is documented, but I can not find any documentation about which exceptions its methods might throw.
For example the <a href="https://msdn.microsoft.com/de-de/library/hh158944(v=vs.118).aspx" target="_blank" rel="noopener noreferrer">GetAsync</a> Method does not have any documentation about possible exceptions. But I assume it throws, for example when the server is unreachable.
Is there somewhere a list of exceptions this class might throw?

i am using dotnet core 1.1 on linux, and i am having issues when i want to split up the identityContext from my regular dbContext, whenever i run the following line in my startup.cs --&gt; configure:

 
    //... some other services
    using (var serviceScope = app.ApplicationServices.GetRequiredService&lt;IServiceScopeFactory&gt;().CreateScope())
    {
        serviceScope.ServiceProvider.GetService&lt;ApplicationDbContext&gt;().Database.Migrate();
        //running other database.migrations here + seeding data. But it is the line above that causes problems

So this line throws the exception: The entity type &#39;IdentityUserLogin&lt;string&gt;&#39; requires a primary key to be defined


I simply don&#39;t understand this, why is it my job to give the IdentityUserLogin a primary key??, it is a 3rd party class and i haven&#39;t even touched it. I have the following simple setup:

    
    
    namespace EsportshubApi.Models
    {
        public class ApplicationDbContext :  IdentityDbContext&lt;ApplicationUser&gt;
        {
            public ApplicationDbContext(DbContextOptions&lt;ApplicationDbContext&gt; options) : base(options)
            {
            }
    
            public ApplicationDbContext()
            {
    
            }
    
            protected override void OnModelCreating(ModelBuilder modelBuilder)
            {
                base.OnModelCreating(modelBuilder);
    
                
            }
        }
    }

And the applicationUser:


    namespace EsportshubApi.Models.Entities
    {
    
        public class ApplicationUser : IdentityUser
        {
            public ApplicationUser() { }
    
            public static ApplicationUserBuilder Builder()
            {
                return new ApplicationUserBuilder(new ApplicationUser());
            }
    
            public int AccountId { get; set; }
            public Guid AccountGuid { get; set; }
            public string Salt { get; set; }
            public bool Verified { get; set; }
            public string Checksum { get; set; }
            public string Password { get; set; }
            public DateTime Created { get; set; }
            public DateTime Updated { get; set; }
        }
    
    }

In my startup i am configuring the identity framework the following way:

configureServices:

    services.AddEntityFrameworkSqlServer().AddMySQL().AddDbContext&lt;ApplicationDbContext&gt;(options =&gt;
                        options.UseMySQL(config[&quot;ConnectionStrings:DefaultConnection&quot;]));

And 

Configure:

     app.UseIdentity();

My project is opensourced at : [my github repo][1]


  [1]: https://github.com/DenLilleMand/esportshubapi

if that helps. 

I have tried a lot of things. The two most promising was deriving all of the classes used in this generic show, and passing them in explicitly, tried to change all of their keys to ints etc. And that gave the exact same error just with `int` instead of string.  The other way i tried was to do the following inside of `OnModelCreating` to give IdentityUserLogin a primary key by e.g :

      
     modelBuilder.Entity&lt;IdentityUserLogin&lt;int&gt;&gt;()
                .Property(login =&gt; login.UserId)
                .ForMySQLHasColumnType(&quot;PK&quot;)
                .UseSqlServerIdentityColumn()
                .UseMySQLAutoIncrementColumn(&quot;AI&quot;);

As you can see, this was back when i had UserId as a integer, but i am not even sure if the UserId should be its primaryKey. I can get other errors instead of this one, that says

&gt; IdentityUserLogin is part of a hierarchy, and it has no discriminator values

But if I had discriminator values it eventually just goes back to this error. The weirdest part i think is that i have the EXACT same implementation as the UnicornStore github example, that uses a bit of the identity framework as well .... So i really need your help guys. Can reproduce this error by downloading the project, copying the `default.appsettings.json` into `appsettings.json`, put in a valid connectionstring, `dotnet restore`, run with `dotnet run --environment Development`.

I even tried to change out the implementation to use a MSSQL database instead of MySQL, but that gave the exact same error. 

The entity type &#39;IdentityUserLogin&lt;string&gt;&#39; requires a primary key to be defined

I just installed the newly released Visual Studio 2017 Enterprise (RC). I&#39;m having trouble getting it to work with [Code Contracts][1], however. I have no problem using Code Contracts with Visual Studio 2015. Am I missing something?


  [1]: https://docs.microsoft.com/en-us/dotnet/framework/debug-trace-profile/code-contracts

Does Visual Studio 2017 work with Code Contracts?

I am trying to figure out how to run a specific migration from the package manager in nuget.

I have tried to run:


     update-database -TargetMigration test32

But I do get this message:

A parameter cannot be found that matches parameter name &#39;TargetMigration&#39;.

I read about that command from Microsoft&#39;s documentation to a previous ef version.

So I am not sure how it is in ef core.

Entity framework Core Update-database specific migration

[![error][1]][1]

I want to publish a sample .net core web application on my pc&#39;s IIS manager but I failed. I am using Microsoft guidance but it doesn&#39;t work for me, if you have reasonable experience to fix this problem I would be grateful to see your suggestions.


  [1]: https://i.stack.imgur.com/vbZ03.png

HTTP Error 500.19 when publish .net core project into iis with 0x80070005

I&#39;ve installed Visual Studio 2017 Community that was released a week ago, and I started exploring the new features of C# 7.

So I created a simple method that returns two values:

    public class Program
    {
        public static void Main(string[] args)
        {
            (int sum, int count) a = ReturnTwoValues();
        }
    
        static (int sum, int count) ReturnTwoValues() =&gt; (1, 1);
    }

Compiler is generating an error:

&gt; Error	CS8137	Cannot define a class or member that utilizes tuples
&gt; because the compiler required type
&gt; &#39;System.Runtime.CompilerServices.TupleElementNamesAttribute&#39; cannot be
&gt; found. Are you missing a reference?

I tried finding a reference in the framework with this name, but with no luck !

**If we need additional stuff to use C# 7.0 features, then it is very weird that we need to do that for every project ?!**

Unable to return Tuple from a method using Visual Studio 2017 and C# 7.0

I am trying to download file from a URL and I have to choose between WebClient and HttpClient. I have referenced [this][1] article and several other articles on the internet. Everywhere, it is suggested to go for HttpClient due to its great async support and other .Net 4.5 privileges. But I am still not totally convinced and need more inputs. 

I am using below code to download file from internet:

**WebClient:**

    WebClient client = new WebClient();
    client.DownloadFile(downloadUrl, filePath);

**HttpClient:**

    using (HttpClient client = new HttpClient())
    {        
        using (HttpResponseMessage response = await client.GetAsync(url))
        using (Stream streamToReadFrom = await response.Content.ReadAsStreamAsync())
        {
    	}
    }

From my perspective, I can see only one disadvantage in using WebClient, that would be the non async call, blocking the calling thread. But what if I am not worried about the blocking of thread or use `client.DownloadFileAsync()` to leverage the async support? 

On the other hand, if I use HttpClient, ain&#39;t I loading every single byte of a file into memory and then writing it to a local file? If the file size is too large, won&#39;t memory overhead be expensive? Which could be avoided if we use WebClient, since it will directly write to local file and not consume system memory.

So, if performance is my utter priority, which approach should I use for download? I would like to be clarified if my above assumption is wrong, and I am open to alternate approach as well.

  [1]: https://stackoverflow.com/questions/20530152/deciding-between-httpclient-and-webclient

Download file with WebClient or HttpClient?

I am trying to implement HttpCache through interceptor. Following is the caching-interceptor.service.ts

    import { HttpRequest, HttpResponse, HttpInterceptor, HttpHandler, HttpEvent } from &#39;@angular/common/http&#39;
    import { Injectable } from &#39;@angular/core&#39;;
    import { Observable } from &#39;rxjs/Observable&#39;;
    
    import &#39;rxjs/add/operator/do&#39;;
    import &#39;rxjs/add/observable/of&#39;;
    
    export abstract class HttpCache {
      abstract get(req: HttpRequest&lt;any&gt;): HttpResponse&lt;any&gt;|null;
      abstract put(req: HttpRequest&lt;any&gt;, resp: HttpResponse&lt;any&gt;): void;
    }
    
    
    
    @Injectable()
    export class CachingInterceptor implements HttpInterceptor {
        constructor(private cache: HttpCache) {}
    
        intercept(req: HttpRequest&lt;any&gt;, next: HttpHandler) : Observable&lt;HttpEvent&lt;any&gt;&gt; {
            if(req.method !== &#39;GET&#39;){
                return next.handle(req);
            }
    
            const cachedResponse = this.cache.get(req);
    
            if(cachedResponse){
                return Observable.of(cachedResponse);
            }
    
            return next.handle(req).do(event =&gt; {
                if(event instanceof HttpResponse){
                    this.cache.put(req, event);
                }
            })
        }
    }

and I am calling from test.service.ts

    import { Injectable } from &#39;@angular/core&#39;;
    import { Headers, Http, Response} from &#39;@angular/http&#39;;
    import { HttpClient} from &#39;@angular/common/http&#39;;
    import { Observable } from &#39;rxjs/Observable&#39;;
    import { ReplaySubject } from &#39;rxjs/ReplaySubject&#39;;
    
    import &#39;rxjs/add/operator/map&#39;;
    import &#39;rxjs/add/operator/catch&#39;;
    
    import { BehaviorSubject } from &#39;rxjs/BehaviorSubject&#39;;
    
    import { APIService } from &#39;./api.service&#39;;
    import { CachingInterceptor } from &#39;./caching-interceptor.service&#39;;
    import { ConfigurationService } from &#39;./configuration.service&#39;;
    import { AuthenticationStatus, IAuthenticationStatus } from &#39;../models&#39;;
    import { User } from &#39;../models/user.model&#39;;
    
    @Injectable()
    export class PlatformService extends APIService {
    
    
    
      constructor(private http: Http, public httpClient: HttpClient, private configuration: ConfigurationService,
         public cachingInterceptor: CachingInterceptor) {
        super();
    
       
      }
    
      getUserById(id: string) {
        console.log(this.requestOptions);
        return this.httpClient.get(this._getAPIUrl(&#39;user/&#39; + id),this.requestOptions).
          subscribe(res =&gt; res);
      }
      get requestOptions(): RequestOptions {
        const tokenObj = window.localStorage.getItem(&#39;TOKEN&#39;);
        const token = JSON.parse(tokenObj);
        const headers = this.headers;
        headers.append(&#39;Authorization&#39;, &#39;Bearer &#39; + token.token);
        headers.append(&#39;Access-Control-Allow-Origin&#39;, &#39;*&#39;);
        return new RequestOptions({ headers: headers });
      }
    
    
    }

and Module file is following

    import { CommonModule } from &#39;@angular/common&#39;;
    import { HTTP_INTERCEPTORS, HttpClient } from &#39;@angular/common/http&#39;;
    import { FormsModule } from &#39;@angular/forms&#39;;
    
    import { ModuleWithProviders, NgModule } from &#39;@angular/core&#39;;
    
    import { PlatformService } from &#39;../../services/platform.service&#39;;
    import { CachingInterceptor } from &#39;../../services/caching-interceptor.service&#39;;
    
    
    @NgModule({
      imports: [CommonModule, FormsModule],
    
      declarations: [],
    
      exports: [],
    
      entryComponents: [EntryHereComponent]
    })
    export class StructurModule {
      public static forRoot(): ModuleWithProviders {
        return { ngModule: StructurModule, providers: [PlatformService,
           {
            provide: HTTP_INTERCEPTORS,
            useExisting: CachingInterceptor,
            multi: true
        },HttpClient] };
      }
    }



I don&#39;t understand, what are missing so it giving error 

&gt; No provider for HttpHandler.

If I add HttpHandler in provider in module file, It start giving error for  provide: HTTP_INTERCEPTORS, component.

Error: No provider for HttpHandler in angular2

I am trying to use HttpClient in my .net core 2.0 project and for that I have injected HttpClient in my controller. But when I am trying to configure httpclient in my startup.cs I am getting this error: &quot;IServiceCollection does not contain a defintion for AddHttpClient&quot;. I have already referenced `using Microsoft.AspNetCore.Http;` and `using Microsoft.Extensions.DependencyInjection;` and here is what I am trying to do: 

    services.AddHttpClient&lt;TestController&gt;();

It&#39;s working fine in other project with same namespaces but here I am getting the error. Any help?

IServiceCollection does not contain a defintion for AddHttpClient

I am using a third party library ([Splunk c# SDK][1] ) in my ASP.NET core application.  I am trying to connect to my localhost Splunk service via this SDK, but I get an exception saying: 

&gt; System.Net.Http.HttpRequestException: The SSL connection could not be established, see inner exception.

And The inner exception says:

&gt; The remote certificate is invalid according to the validation procedure.

This SDK uses HTTP client under the hood, but I don&#39;t have access to this object to configure HttpClientHandler.  

All my search on google ends up using ServicePointManager to bypass the SSL validation, but this solution doesn&#39;t work in Asp.Net core. 

    ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };

Is there any way to bypass this validation in asp.Net core?

  [1]: http://dev.splunk.com/csharp

Content Type	Original Author	Original Content on Stackoverflow
Question	Nathan	View Question on Stackoverflow
Solution 1 - C#	BritishDeveloper	View Answer on Stackoverflow

Which exceptions can HttpClient throw?

C# Problem Overview

C# Solutions

Solution 1 - C#

Why are the memory addresses of string literals so different from others', on Linux?

Angular 2 filter/search list

Attributions