Why does .NET generate two web.config files in an

问题:

I am new in MVC 3. What is the reason to use two web.config files?

What is difference between that 2 web.config files, and what is the purpose of each and its function?

回答1:

I'd like to add to this that the Web.Config in the /Views folder is a great (if not thé) way to declare namespaces specifically for your views in. In a web application it is very possible almost every view gets a ViewModel (instead of your actual model) passed to it. Declaring the full namespace after @model or having the same @using App.Web.Viewmodels gets tedious. This way, all viewmodels are automatically available and you have to do extra work to get the real models in scope, which should then set of some alarm bells immediatly.

Also, usually an application can get a lot of extension-methods specifically for use in the view (the HTML-helper jumps into mind). It makes sense to define the namespace to this extension class in the /Views/Web.Config. That way you never wonder "Why cant IntelliSense find my @Html.ImageLink() method??!"

回答2:

This is an example of web.config file inheritance. From MSDN

You can distribute ASP.NET configuration files throughout your application directories to configure ASP.NET applications in an inheritance hierarchy. This structure allows you to achieve the level of configuration detail that your applications require at the appropriate directory levels without affecting configuration settings at higher directory levels.

Specifically, for MVC projects, the web.config in the View subdirectory is used to tailor the .cshtml / .aspx files. You can use web.config files in subfolders to extend, override, and remove settings inherited from the app's own root, and further up the hierarchy, e.g. up to machine.config

Common configurations in the /Views/web.config include:

• Blocking requests attempting to access razor and aspx views directly (these need to be served from Controllers via the appropriate routes). A 404 response is configured for such direct requests, e.g.

<add path="*" verb="*" type="System.Web.HttpNotFoundHandler"/>

• To setup default import namespaces for the view pages, which would otherwise have to be explicitly added via using. You can add namespaces for your common custom assemblies here (e.g. custom html helper extensions) e.g.

  <namespaces>
    <add namespace="System.Web.Mvc" />
    <add namespace="System.Web.Mvc.Ajax" />
    <add namespace="System.Web.Mvc.Html" />
    ...

• To configure the anti-xss RequestValidation filter for MVC. The comment added in the config explains this best:

<!--
    Enabling request validation in view pages would cause validation to occur
    after the input has already been processed by the controller. By default
    MVC performs request validation before a controller processes the input.
    To change this behavior apply the ValidateInputAttribute to a
    controller or action.
 -->

回答3:

The web.config file exists in the Views folders to prevent access to your views by any means other than your controller. In the MVC design pattern, controllers are supposed to route requests and return a rendered view to the calling client.

means localhost9999://Home/Index.cshtml should not be directly accessible.

回答4:

View has its own config. If you are dealing with areas Then you will come to know about more than one config.

Actually The point is that view's Web.Config is for view specifc configutation such as blocking direct access to the views.

EDIT 1: More Explaination as asked in comments.

The web.config file exists in the Views folders to prevent access to your views by any means other than your controller. In the MVC design pattern, controllers are supposed to route requests and return a rendered view to the calling client. That means localhost9999://Home/Index.cshtml should not be directly accessible.

回答5:

ASP.NET configuration is stored in web.config files (XML files).

These files can appear in many directories in an ASP.NET application. They help to configure application behaviour even before after deploying, based on the fact that you can edit them with notepad. Also they keep separated your code and your configuration data.

Every web.config file applies to to the directory that it exists and ALL the child subdirectories. Web.config files in child directory may be used to override the parent's web.config file.

You have the option of overriding individual files or directories by using the location element. See LINK

The settings inheritance rules are as foillows.

First there is the machine.config file which is located usually in systemroot\Microsoft.NET\Framework\versionNumber\CONFIG\

In the same directory exists a 'master' web.config file that defines settings for ALL asp.net application that are running in the machine.

Then come your web.config files that exist in your application.

More Info:

ASP.NET configuration overview

ASP.NET Configuration file hierarchy and inheritance

回答6:

In addition to distributing your settings for your project simple way you can turn it at runtime to make a publication. One hand on the wheel. See:

Web.config Transformations

Transformation Syntax