Using Server in Mvc.Controller

Question

I have my own inherited App.Controller from Mvc.Controller which then all of my controllers inherit from. I wrote a provider utilizing an interface and implemented it as MyService and the constructor takes the Server property of Mvc.Controller which is of HttpServerUtilityBase.

However, I instantiate MyService in App.Controller's constructor. The problem is that the Server property of the Controller is null when constructing MyService. I have used public Controller () : base() { } to get the base to be constructed. However, Server remains null.

I would like to avoid Web.HttpContext.Current.Server if possible.

Has any one have a work around for this problem?

Edit: Well, I have implemented tvanfosson's suggestion, and when my app constructs MyService in the property get method, Server is still null.

Edit 2: Nevermind, I was a goof. I had another Controller using Server aswell and did not change that. Case closed.

tvanfosson · Accepted Answer · 2009-03-11 02:22:27Z

8

Use delayed initialization to construct your service.

private MyService service;
public MyService Service
{
    get
    {
         if (this.service == null)
         {
             this.service = new MyService(this.Server);
         }
         return this.service;
    }
}

Then, your service isn't actually instantiated until it is used in the controller action and by that time the Server property has been set.

answered Mar 11, 2009 at 2:22

tvanfosson

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2 Comments

Craig Stuntz Over a year ago

Or override Controller.Initialize, which fires at the right time.

tvanfosson Over a year ago

The best part of delayed initialization is that it doesn't ever happen if the property is never accessed.

yfeldblum · Accepted Answer · 2009-03-11 02:10:09Z

0

I instantiate MyService in App.Controller's constructor.

There's your problem. You need to pass an instance of MyService which has already been constructed into your App.Controller's constructor. Take a look at the Inversion of Control / Dependency Injection patterns, and take a look at some of the libraries which make these patterns easy (see this list).

answered Mar 11, 2009 at 2:10

yfeldblum

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2 Comments

yfeldblum Over a year ago

ASP.NET MVC is very pluggable, and you can either write your own ControllerFactory or use one from a library. I like Autofac, so I tell ASP.NET MVC to use Autofac's ControllerFactory. Autofac autowires the arguments to my controllers' constructors, and the constructors are free of all "dirtiness."

MrLore Over a year ago

If constructing MyService requires Controller.Server then it can't be constructed before the controller you pass it to

Chris Hynes · Accepted Answer · 2009-03-11 02:30:01Z

0

Why do you need the Server reference? Are you doing stuff like url/html encoding? If so, you could use HttpUtility instead and get rid of the context reference entirely.

answered Mar 11, 2009 at 2:30

Chris Hynes

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peter_the_oak · Accepted Answer · 2017-04-24 09:27:17Z

0

This is a very old question, but the subject is still relevant. So, one hint in 2017 that was possibly not available in 2009:

It is true that in the Controller constructor Server is null. But you can use the OnActionExecuting event:

protected override void OnActionExecuting(ActionExecutingContext filterContext) 
{
    base.OnActionExecuting(filterContext);

    CurrentServer = Server; // CurrentServer is some instance variable I need later.
}

This works fine for me.

answered Apr 24, 2017 at 9:27

peter_the_oak

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vapcguy · Accepted Answer · 2018-11-20 23:15:18Z

0

According to this site, if you have this Controller:

public class MyController : Controller
{
  private string folderPath;

  public MyController()
  {       
    // Throws an error because Server is null
    folderPath = Server.MapPath("~/uploads"); 

    // Throws an error because this.ControllerContext is null
    folderPath = this.ControllerContext.HttpContext.Server.MapPath("~/uploads"); 
  }
}

Then you want to initialize it this way:

protected override void Initialize(System.Web.Routing.RequestContext requestContext)
{
  base.Initialize(requestContext);

  // now Server has been initialized
  folderPath = Server.MapPath("~/uploads"); 
}

answered Nov 20, 2018 at 23:15

vapcguy

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