The following code should work:

    string contentType;
    new FileExtensionContentTypeProvider().TryGetContentType(FileName, out contentType);
    return contentType ?? &quot;application/octet-stream&quot;;

There is a NuGet package [MimeTypes](https://www.nuget.org/packages/MimeTypes/1.0.4) which works with .Net Core projects as an alternative to `FileExtensionContentTypeProvider`. I&#39;m not aware of any other mime-type resolver package, which works with .Net Core (at least so far).

The usage is simple:

    string fileName = &quot;trial.jpg&quot;;
    string mime = MimeKit.MimeTypes.GetMimeType(fileName);

System.Web is not moved to .NetCore because it relies too much on API&#39;s that are platform specific. You could take a look at Microsoft reference source:

https://github.com/Microsoft/referencesource/blob/master/System.Web/MimeMapping.cs

The code is subject to a MIT license.

I have a variable in the parent component that might be changed by child, parent will be using this variable in the view and thus has to propagate changes.

    import {Component, View} from &#39;angular2/core&#39;;
    
    @Component({selector: &#39;parent&#39;})
    @View({
        directives: [Child],
        template: `&lt;childcomp&gt;&lt;/childcomp&gt;`
    })
    class Parent {
        public sharedList = new Array();
        constructor() {
        }
    }


    @Component({selector: &#39;child&#39;})
    @View({template: `...`})
    class Child {
        constructor() {
            //access &#39;sharedList&#39; from parent and set values
            sharedList.push(&quot;1&quot;);
            sharedList.push(&quot;2&quot;);
            sharedList.push(&quot;3&quot;);
            sharedList.push(&quot;4&quot;);
        }
    }
    


Angular2: child component access parent class variable/function

I have *Angular components* and first component uses the second one as a *directive*.
They should share the same model **object**, which is initialized in the first component.
How can I pass that model to the second component? 

How to pass object from one component to another in Angular 2?

I&#39;m trying to move my old mvc5 project to asp net core.
Old code was:

    public string ContentType
	{
		get
		{
			if (!string.IsNullOrEmpty(FileName))
				return MimeMapping.GetMimeMapping(FileName);
			return null;
		}
	}

Error is

&gt; The name &#39;MimeMapping&#39; does not exist in the current context

[![enter image description here][1]][1]


  [1]: http://i.stack.imgur.com/7jA4r.png

Using MimeMapping in ASP.NET Core

I'm trying to move my old mvc5 project to asp net core.
Old code was:
<pre><code class="hljs language-csharp">public string ContentType
{
	get
	{
		if (!string.IsNullOrEmpty(FileName))
			return MimeMapping.GetMimeMapping(FileName);
		return null;
	}
}
</code></pre>
Error is
> The name 'MimeMapping' does not exist in the current context
<a href="http://i.stack.imgur.com/7jA4r.png" target="_blank" rel="noopener noreferrer"><img src="http://i.stack.imgur.com/7jA4r.png" alt="enter image description here"></a>

I&#39;ve deployed my c#, asp.net 5, mvc 6 app to a windows 2008 server.  I&#39;ve fired up `dnx web` and it is listening to port 5000 and works fine when accessing from local computer. 

How do I get it to listen to non-localhost requests?

P.S.  This [question][1] is not a duplicate of this...it refers to asp.net pre RC1 when hosting.ini actually had an .ini format.  Now, it&#39;s JSON and I can&#39;t find any documentation on what should actually be in it.

P.P.S.  The real solution is in the non-accepted [answer][2] to the linked question, with a massive caveat.  Steps:

 1. Change your project.json per the linked answer.
 2. Publish your project to your server.
 3. On the server, go to ...\approot\src\YourProject folder and open a command window there.
 4. Run `dnx web` - it will fail
 5. Run `dnu restore`
 6. Run &#39;dnu build`
 7. Run &#39;dnx web` - the web server should now start fine

# P.S.  For people upvoting this question.  It&#39;s outdated.  Very badly outdated!
It applied to the early versions of the .NET Core.  The question and the answers certainly aren&#39;t applicable for the current versions of the framework (e.g. 2.x, 3.x)

  [1]: https://stackoverflow.com/questions/33975949/asp-net-5-kestrel-connect-within-lan
  [2]: https://stackoverflow.com/a/34092934/9382

How do I get the kestrel web server to listen to non-localhost requests?

In MonoDevelop, when I type &quot;///&quot;, it auto-generates an xml-style comment like this:

    /// &lt;summary&gt;
	/// Describes the variable x
	/// &lt;/summary&gt;
    int x = 0;

Is there a way to get this behavior in Visual Studio Code?

XML Auto Commenting C# in Visual Studio Code

The answers to questions like this: https://stackoverflow.com/questions/400135/c-sharp-listt-or-ilistt always seem to agree that returning an interface is better than returning a concrete implementation of a collection. But I&#39;m struggling with this. Instantiating an interface is impossible, so if your method is returning an interface, it&#39;s actually still returning a specific implementation. I was experimenting a bit with this by writing 2 small methods:

    public static IList&lt;int&gt; ExposeArrayIList()
    {
        return new[] { 1, 2, 3 };
    }

    public static IList&lt;int&gt; ExposeListIList()
    {
        return new List&lt;int&gt; { 1, 2, 3 };
    }

And use them in my test program:

    static void Main(string[] args)
    {
        IList&lt;int&gt; arrayIList = ExposeArrayIList();
        IList&lt;int&gt; listIList = ExposeListIList();
        
        //Will give a runtime error
        arrayIList.Add(10);
        //Runs perfectly
        listIList.Add(10);
    }

In both cases when I try to add a new value, my compiler gives me no errors, but obviously the method which exposes my array as an `IList&lt;T&gt;` gives a runtime error when I try to add something to it. 
So people who don&#39;t know what&#39;s happening in my method, and have to add values to it, are forced to first copy my `IList` to a `List` to be able to add values without risking errors. Of course they can do a typecheck to see if they&#39;re dealing with a `List` or an `Array`, but if they don&#39;t do that, and they want to add items to the collection **they have no other choice to copy the `IList` to a `List`, even if it already is a `List`**. Should an array never be exposed as `IList`?

Another concern of mine is based upon the accepted answer of the [linked question][1] (emphasis mine):

&gt; If you are exposing your class through a library that others will use, **you generally want to expose it via interfaces rather than concrete implementations.** This will help if you decide to change the implementation of your class later to use a different concrete class. In that case the users of your library won&#39;t need to update their code since the interface doesn&#39;t change.

&gt;If you are just using it internally, you may not care so much, and using List&lt;T&gt; may be ok.

Imagine someone actually used my `IList&lt;T&gt;` they got from my `ExposeListIlist()` method just like that to add/remove values. Everything works fine. But now like the answer suggests, because returning an interface is more flexible I return an array instead of a List (no problem on my side!), then they&#39;re in for a treat...

TLDR: 

1) Exposing an interface causes unnecessary casts? Does that not matter?

2) Sometimes if users of the library don&#39;t use a cast, their code can break when you change your method, even though the method remains perfectly fine.

I am probably overthinking this, but I don&#39;t get the general consensus that returning an interface is to be preferred over returning an implementation.


  [1]: https://stackoverflow.com/a/400144/3410196

Is returning IList&lt;T&gt; worse than returning T[] or List&lt;T&gt;?

I have the following view model

    public class ProjectVM
    {
        ....
        [Display(Name = &quot;Category&quot;)]
        [Required(ErrorMessage = &quot;Please select a category&quot;)]
        public int CategoryID { get; set; }
        public IEnumerable&lt;SelectListItem&gt; CategoryList { get; set; }
        ....
    }

and the following controller method to create a new Project and assign a `Category`

    public ActionResult Create()
    {
        ProjectVM model = new ProjectVM
        {
            CategoryList = new SelectList(db.Categories, &quot;ID&quot;, &quot;Name&quot;)
        }
        return View(model);
    }

    public ActionResult Create(ProjectVM model)
    {
        if (!ModelState.IsValid)
        {
            return View(model);
        }
        // Save and redirect
    }

and in the view

    @model ProjectVM
    ....
    @using (Html.BeginForm())
    {
        ....
        @Html.LabelFor(m =&gt; m.CategoryID)
        @Html.DropDownListFor(m =&gt; m.CategoryID, Model.CategoryList, &quot;-Please select-&quot;)
        @Html.ValidationMessageFor(m =&gt; m.CategoryID)
        ....
        &lt;input type=&quot;submit&quot; value=&quot;Create&quot; /&gt;
    }

The view displays correctly but when submitting the form, I get the following error message

&gt;InvalidOperationException: The ViewData item that has the key &#39;CategoryID&#39; is of type &#39;System.Int32&#39; but must be of type &#39;IEnumerable&amp;lt;SelectListItem&amp;gt;&#39;.

The same error occurs using the `@Html.DropDownList()` method, and if I pass the SelectList using a `ViewBag` or `ViewData`.

The ViewData item that has the key &#39;XXX&#39; is of type &#39;System.Int32&#39; but must be of type &#39;IEnumerable&lt;SelectListItem&gt;&#39;

Ok, so basically I have a bunch of tasks (10) and I want to start them all at the same time and wait for them to complete. When completed I want to execute other tasks. I read a bunch of resources about this but I can&#39;t get it right for my particular case...

Here is what I currently have (code has been simplified):

    public async Task RunTasks()
    {
        var tasks = new List&lt;Task&gt;
        {
            new Task(async () =&gt; await DoWork()),
            //and so on with the other 9 similar tasks
        }
    
    
        Parallel.ForEach(tasks, task =&gt;
        {
            task.Start();
        });
    
        Task.WhenAll(tasks).ContinueWith(done =&gt;
        {
            //Run the other tasks
        });
    }
    
    //This function perform some I/O operations
    public async Task DoWork()
    {
        var results = await GetDataFromDatabaseAsync();
        foreach (var result in results)
        {
            await ReadFromNetwork(result.Url);
        }
    }

So my problem is that when I&#39;m waiting for tasks to complete with the `WhenAll` call, it tells me that all tasks are over even though none of them are completed. I tried adding `Console.WriteLine` in my `foreach` and when I have entered the continuation task, data keeps coming in from my previous `Task`s that aren&#39;t really finished.

What am I doing wrong here?

Executing tasks in parallel

What is the purpose of the `ConcurrencyStamp` column in the `AspNetUsers` table in the new ASP.NET MVC 6 identity?

This is the database schema of the `AspNetUsers` table:

[![enter image description here][1]][1]

It is also there in the `AspNetRoles` table:

[![enter image description here][2]][2]

As I remember it wasn&#39;t there in the ASP.NET MVC 5 identity.

What I&#39;ve noticed so far is that it seems to have GUID values as it is defined with the following code:

    /// &lt;summary&gt;
    /// A random value that must change whenever a user is persisted to the store
    /// &lt;/summary&gt;
    public virtual string ConcurrencyStamp { get; set; } = Guid.NewGuid().ToString();

But this documentation is not sufficient for me to understand in which situations it is used.


  [1]: http://i.stack.imgur.com/Zr319.png
  [2]: http://i.stack.imgur.com/6Lbwx.png

What is the purpose of the ConcurrencyStamp column in the AspNetUsers table in the new ASP.NET MVC 6 identity?

I have created a new clean asp.net 5 project (rc1-final). Using Identity Authentication I just have the ApplicationDbContext.cs with the following code:

    public class ApplicationDbContext : IdentityDbContext&lt;ApplicationUser&gt;
    {
        protected override void OnModelCreating(ModelBuilder builder)
        {
            // On event model creating
            base.OnModelCreating(builder);
        }
    }

Please note ApplicationDbContext use IdentityDbContext&lt;ApplicationUser&gt; and not DbContext.

There is any IdentityConfig.cs. Where i need to put the classic  protected override void Seed to create role and user if it does not exist?

How to Seed Users and Roles with Code First Migration using Identity ASP.NET Core

I need some help with the select tag helper in ASP.NET Core.

I have a list of employees that I&#39;m trying to bind to a select tag helper. My employees are in a `List&lt;Employee&gt; EmployeesList` and selected value will go into `EmployeeId` property. My view model looks like this:

    public class MyViewModel
    {
       public int EmployeeId { get; set; }
       public string Comments { get; set; }
       public List&lt;Employee&gt; EmployeesList {get; set; }
    }

My employee class looks like this:

    public class Employee
    {
       public int Id { get; set; }
       public string FullName { get; set; }
    }

My question is how do I tell my select tag helper to use the `Id` as the value while displaying `FullName` in the drop down list?

    &lt;select asp-for=&quot;EmployeeId&quot; asp-items=&quot;???&quot; /&gt;

I&#39;d appreciate some help with this. Thanks.

Select Tag Helper in ASP.NET Core MVC

I&#39;ve been trying to pass data to an action after a redirect by using TempData like so:

    if (!ModelState.IsValid)
	{
		TempData[&quot;ErrorMessages&quot;] = ModelState;
		return RedirectToAction(&quot;Product&quot;, &quot;ProductDetails&quot;, new { code = model.ProductCode });
	}

but unfortunately it&#39;s failing with the following message:

&gt; &#39;`System.InvalidOperationException` The 
&gt; `Microsoft.AspNet.Mvc.SessionStateTempDataProvider&#39;` cannot serialize an
&gt; object of type `&#39;ModelStateDictionary&#39;` to session state.&#39;

I&#39;ve found an issue in [the MVC project in Github][1], but while it explains why I&#39;m getting this error, I can&#39;t see what would be a viable alternative.

One option would be to serialize the object to a json string and then deserialize it back and reconstruct the `ModelState`. Is this the best approach? Are there any potential performance issues I need to take into account? 

And finally, are there any alternatives for either serializing complex object or using some other pattern that doesn&#39;t involve using `TempData`?


  [1]: https://github.com/aspnet/Mvc/issues/2276

Store complex object in TempData

I&#39;m using vNext implementation of DI.
How to pass parameters to constructor?
For example, i have class: 

    public class RedisCacheProvider : ICacheProvider
    {
        private readonly string _connectionString;

        public RedisCacheProvider(string connectionString)
        {
            _connectionString = connectionString;
        }
        //interface methods implementation...
    }


And service register: 

    services.AddSingleton&lt;ICacheProvider, RedisCacheProvider&gt;();

How to pass parameter to constructor of RedisCacheProvider class?
For example for Autofac:

    builder.RegisterType&lt;RedisCacheProvider&gt;()
           .As&lt;ICacheProvider&gt;()
           .WithParameter(&quot;connectionString&quot;, &quot;myPrettyLocalhost:6379&quot;);

Dependency injection, inject with parameters

At times, I&#39;ve seen ``.pickle``, ``.pck``, ``.pcl``, and ``.db`` for files that contain Python pickles, but I am unsure what is the most common or best practice. I know that the latter three extensions are also used for other things.

The related question is: What MIME type is preferred for sending pickles between systems using a REST API?


Preferred (or most common) file extension for a Python pickle

Where can I find a list of all MIME types that are supported by `Firefox` or `Chrome`? All examples I&#39;ve seen so far using `video/webm` only.

All MIME types supported by MediaRecorder in Firefox and Chrome?

I am developing an Angular 4 app and I want to apply some global styles.  Following the [tutorial at the angular site][1], I&#39;ve created a &quot;styles.css&quot; file in the root directory of my app, and I&#39;m referring to that stylesheet in the index.html of my app:

    &lt;link rel=&quot;stylesheet&quot; type=&quot;text/css&quot; href=&quot;styles.css&quot;&gt;

The angular app is successfully compiled:

    $ ng serve 
    ** NG Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200 **
    [...]
    webpack: Compiled successfully.

But when I visit http://localhost:4200 in a Chromium browser, the console shows an error at

    GET http://localhost:4200/styles.css 

In a Firefox browser, the error is a bit more explicit:

    GET 
    http://localhost:4200/styles.css [HTTP/1.1 404 Not Found 15ms]
    The resource from &quot;http://localhost:4200/styles.css&quot; was blocked due to MIME type mismatch (X-Content-Type-Options: nosniff).

Both files, index.html and styles.css are located in the root directory of my angular app. 
I&#39;ve tried to get [more info about the problem][2] :

    nosniff
        Blocks a request if the requested type is
    
            &quot;style&quot; and the MIME type is not &quot;text/css&quot;, or
            &quot;script&quot; and the MIME type is not a JavaScript MIME type.

But I don&#39;t understand why it&#39;s bloking the request, since I&#39;ve specified `type=&quot;text/css&quot;` when referencing the stylesheet.



  [1]: https://angular.io/tutorial/toh-pt5#global-application-styles
  [2]: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options

CSS file blocked: MIME type mismatch (X-Content-Type-Options: nosniff)

I used to have ElasticSearch 5.2, and just upgraded to 6.0. 

I am trying to create an index template following guide [here](https://www.elastic.co/guide/en/elasticsearch/reference/current/indices-templates.html), but got error

    Content-Type header [application/x-www-form-urlencoded] is not supported

My query is 


    curl -X PUT localhost:9200/_template/template_1 -d &#39;
    {
      &quot;index_patterns&quot;: [&quot;te*&quot;, &quot;bar*&quot;],
      &quot;mappings&quot;: {
        &quot;type1&quot;: {
          &quot;properties&quot;: {
            &quot;host_name&quot;: {
              &quot;type&quot;: &quot;keyword&quot;
            }
          }
        }
      }
    }&#39;

Content-Type header [application/x-www-form-urlencoded] is not supported on Elasticsearch

I&#39;m working on a website that uses `gulp` to compile and browser sync to keep the browser synchronised with my changes.

The gulp task compiles everything properly, but on the website, I&#39;m unable to see any style, and the console shows this error message:

&gt; Refused to apply style from
&gt; &#39;http://localhost:3000/assets/styles/custom-style.css&#39; because its
&gt; MIME type (&#39;text/html&#39;) is not a supported stylesheet MIME type, and
&gt; strict MIME checking is enabled.

Now, I don&#39;t really understand why this happens.

The HTML includes the file like this (which I am pretty sure is correct):

    &lt;link rel=&quot;stylesheet&quot; type=&quot;text/css&quot; href=&quot;assets/styles/custom-style.css&quot;/&gt;

And the stylesheet is a merge between Bootstrap &amp; font-awesome styles for now (nothing custom yet).

The path is correct as well, as this is the folder structure:

    index.html
    assets
    |-styles
      |-custom-style.css

But I keep getting the error.

What could it be? Is this something (maybe a setting?) for gulp/browsersync maybe?


Content Type	Original Author	Original Content on Stackoverflow
Question	Sauron	View Question on Stackoverflow
Solution 1 - C#	Mark G	View Answer on Stackoverflow
Solution 2 - C#	Matyas	View Answer on Stackoverflow
Solution 3 - C#	SynerCoder	View Answer on Stackoverflow

Using MimeMapping in ASP.NET Core

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

How to pass object from one component to another in Angular 2?

Angular2: child component access parent class variable/function

Attributions