Strange auto-import namespace in my Razor views

Question

Today I noticed that, for example, "System" and "System.Web.Security" are imported into all my razors, although I did not import them actively. I checked:

• @using directive
• web.config (EDIT: also global web.config)
• AddGlobalImport

EDIT:

This namespace import seems to be tightly linked to Razor source code

https://github.com/ASP-NET-MVC/aspnetwebstack/blob/master/src/System.Web.WebPages.Razor/WebPageRazorHost.cs

    private WebPageRazorHost()
    {
        NamespaceImports.Add("System");
        NamespaceImports.Add("System.Collections.Generic");
        NamespaceImports.Add("System.IO");
        NamespaceImports.Add("System.Linq");
        NamespaceImports.Add("System.Net");
        NamespaceImports.Add("System.Web");
        NamespaceImports.Add("System.Web.Helpers");
        NamespaceImports.Add("System.Web.Security");
        NamespaceImports.Add("System.Web.UI");
        NamespaceImports.Add("System.Web.WebPages");
        NamespaceImports.Add("System.Web.WebPages.Html");

        // ...
    }

It also seems that I cannot disable them by setting "clear" at the beginning of my web.config:

<system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
    <pages pageBaseType="System.Web.Mvc.WebViewPage" >
        <namespaces>
            <clear />
            <add namespace="System.Web.Helpers" />
            <add namespace="System.Web.Mvc" />
            <add namespace="System.Web.Mvc.Ajax" />
            <add namespace="System.Web.Mvc.Html" />
            <add namespace="System.Web.Routing" />
            <add namespace="System.Web.WebPages" />
        </namespaces>
    </pages>
</system.web.webPages.razor>

Thus, this problem can be fixed if the source of Razor is not changed.

Answer 1

, : Razor , . , . :

• System.Collections.Generic
• System.IO
• System.Linq
• System.Net
• System.Web
• System.Web.Helpers
• System.Web.Security
• System.Web.UI
• System.Web.WebPages
• System.Web.WebPages.Html

100%, , , .

Answer 2

, :

systemroot\Microsoft.NET\Framework\versionNumber\CONFIG\Web.config  

:

 <pages>
            <namespaces>
                <add namespace="System" />
                <add namespace="System.Collections" />
                <add namespace="System.Collections.Generic" />
                <add namespace="System.Collections.Specialized" />
                <add namespace="System.ComponentModel.DataAnnotations" />
                <add namespace="System.Configuration" />
                <add namespace="System.Linq" />
                <add namespace="System.Text" />
                <add namespace="System.Text.RegularExpressions" />
                <add namespace="System.Web" />
                <add namespace="System.Web.Caching" />
                <add namespace="System.Web.DynamicData" />
                <add namespace="System.Web.SessionState" />
                <add namespace="System.Web.Security" />
                <add namespace="System.Web.Profile" />                    
                <add namespace="System.Xml.Linq" />
            </namespaces>  
 </pages>

EDIT:

SO :

Preview 1 Razor WebForms. - , WebForms. follwing web.config( ):

<configSections>
  <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
    <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
  </sectionGroup>
</configSections>

<system.web.webPages.razor>
  <pages pageBaseType="System.Web.Mvc.WebViewPage">
    <namespaces>
      <add namespace="MyCustomHelpers" />
    </namespaces>
  </pages>
</system.web.webPages.razor>

Answer 3

, ( System.Web.UI Razor). . .

, , , . , .

MvcWebRazorHostFactory. factory , , .

:

namespace TestCode
{
    using System.Web.WebPages.Razor;
    using System.Web.Mvc;
    using System.Web.Mvc.Razor;

    public class CustomWebRazorHostFactory : MvcWebRazorHostFactory
    {
        public override WebPageRazorHost CreateHost(string virtualPath, string physicalPath)
        {
            WebPageRazorHost host = base.CreateHost(virtualPath, physicalPath);
            host.NamespaceImports.Remove("System.Web.UI");
            return host;
        }
    }
}

Then I replaced web.config with using my factory instead of the standard one:

<system.web.webPages.razor>
    <!--<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />-->
    <host factoryType="TestCode.CustomWebRazorHostFactory" />

Bingo!