How to use a custom HttpHandler in MVC?

Does anyone have an example of how to use a custom HttpHandler in MVC?

I wrote a simple image handler that displays thumbnails on a view, but I can't get it to fire.

I have it set in my web.config under the httpHandlers section, and in my html like this:

<img src="/image.ashx?PhotoID=1&Size=M" />

The handler never fires. What am I missing? Do I need to create a route for it also?

Thanks.

Re: How to use a custom HttpHandler in MVC?

You can use the handler normal like other applications, no need to routes for using it.

may be you have error on the code or wronge path or something else.

Re: How to use a custom HttpHandler in MVC?

If you run your application in IIS7 Integrated mode, the http handler must be defined in handlers element of system.webServer section (httpHandlers section works for IIS6 and IIS7 Classic mode).

Re: How to use a custom HttpHandler in MVC?

Also check http://blog.maartenballiauw.be/post/2008/05/ASPNET-MVC-custom-ActionResult.aspx, it features an image action result which just uses the standerd ASP.NET MVC lifecycle.

Re: How to use a custom HttpHandler in MVC?

Ahmed Abu Dagga

You can use the handler normal like other applications, no need to routes for using it.

may be you have error on the code or wronge path or something else.

It doesn't seem like I have an error in my code because none is thrown. When I step through the code, it never gets to the handler.

Re: How to use a custom HttpHandler in MVC?

CW2

If you run your application in IIS7 Integrated mode, the http handler must be defined in handlers element of system.webServer section (httpHandlers section works for IIS6 and IIS7 Classic mode).

It will be running on IIS 6 and I have all the necessary web.config settings made.

When I debug and place a breakpoint in the handler, the pages loads without ever stepping into the handler. Any thoughts?

Re: How to use a custom HttpHandler in MVC?

maartenba

Also check http://blog.maartenballiauw.be/post/2008/05/ASPNET-MVC-custom-ActionResult.aspx, it features an image action result which just uses the standerd ASP.NET MVC lifecycle.

Maarten, this does give me ideas. I'll give it a try. But I would still like to know why my handler never gets fired. [:S]

Re: How to use a custom HttpHandler in MVC?

<div mce_keep="true">Is your path in the image OK? (i.e. if you type http://localhost:whatever//image.ashx?PhotoID=1&Size=M in your browser, is it fired?)</div>

<div mce_keep="true">Try adding the following to global.asax.cs:

routes.IgnoreRoute("{handler}.ashx?{*path}", new { handler = @"image" });

</div>

<div mce_keep="true">Just to be sure... Can you post your web.config (httpHandlers section) and global.asax.cs class?</div>

Re: How to use a custom HttpHandler in MVC?

maartenba
<div>Is your path in the image OK? (i.e. if you type http://localhost:whatever//image.ashx?PhotoID=1&Size=M in your browser, is it fired?)</div>
<div>Try adding the following to global.asax.cs:
routes.IgnoreRoute("{handler}.ashx?{*path}", new { handler = @"image" });
</div>
<div>Just to be sure... Can you post your web.config (httpHandlers section) and global.asax.cs class?</div>

Item 1: Image path - no I don't think the path is ok. If I enter the complete path to the handler I get a controller error. (I'm using Dependency Injection, see below) Here's the html for the image tag:

<img src="ImageHandler.ashx?PhotoID=1&Size=M" alt="Photo Number 1" />

Here's my web.config httpHandlers section:

<httpHandlers>
	<remove verb="*" path="*.asmx"/>
	<add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
	<add verb="*" path="*_AppService.axd" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
	<add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false"/>
	<add verb="*" path="*.mvc" validate="false" type="System.Web.Mvc.MvcHttpHandler, System.Web.Mvc, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
	<add verb="*" path="ImageHandler.ashx" validate="false" type="PersonalKit.Mvc.Web.Views.Shared.ImageHandler, PersonalKit.Mvc.Core"/>
</httpHandlers>

Just so you know, and this could be an issue, the location of the physical ashx file is: /Views/Shared/Imagehandler.ashx.

I did try adding the path to the img tag, but that didn't work either. No matter what I do, the handler does not get fired.

What does the routes.IgnoreRoute(...) do? It seems like it should ignore anything with this filename or extension. Is that not the case?

Here's something else that might help you, I'm using a Dependency Injector to handle the mapping to classes. Do you think I need to map this some how? I'm using the Microsoft.Practices.Unity container for the IoC. I'm not sure if this is part of the problem, but it might be.

Thanks for your help.

Here's my Global.asax class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Routing;
using System.Configuration;

using Microsoft.Practices.Unity;
using Microsoft.Practices.Unity.Configuration;

using PersonalKit.Mvc.Services;
using PersonalKit.Mvc.Data;
//using PersonalKit.Mvc.Core.HttpHandlers;
using PersonalKit.Mvc.Web.Views.Shared;

namespace PersonalKit.Mvc.Web
{
    public class MvcApplication : System.Web.HttpApplication
    {
        public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                "Default",                                              // Route name
                "{controller}/{action}/{id}",                           // URL with parameters
                new { controller = "Home", action = "Index", id = "" }  // Parameter defaults
            );

        }

        protected void Application_Start()
        {
            IUnityContainer container = new UnityContainer();

            UnityConfigurationSection section = (UnityConfigurationSection)ConfigurationManager.GetSection("unity");
            section.Containers.Default.Configure(container);

            UnityController.UnityControllerFactory factory = new PersonalKit.Mvc.UnityController.UnityControllerFactory(container);
            ControllerBuilder.Current.SetControllerFactory(factory);

            container.Resolve();

            RegisterRoutes(RouteTable.Routes);
        }
    }
}

Re: How to use a custom HttpHandler in MVC?

Can you try putting the handler in the root of the website?

Re: How to use a custom HttpHandler in MVC?

maartenba
Can you try putting the handler in the root of the website?

That didn't work either. I think it might have something to do with the Dependency Injection I'm using.

I'll keep looking. I'm determined to figure this out! [:)]

Thanks.

Re: How to use a custom HttpHandler in MVC?

FYI:

I had this same problem and just solved it by adding an IgnoreRoute:

public static void RegisterRoutes(RouteCollection routes)


{


         routes.IgnoreRoute("{resource}.axd/{*pathInfo}");


         routes.IgnoreRoute("Custom.sfx");


}

Provided classic/integration httpHandlers/handlers is setup properly and no authentication is blocking you it should be good to go.

Re: How to use a custom HttpHandler in MVC?

I was up against this problem last night, and here is how I solved it

I added this to my Global.asax file, before I defined my routes :

routes.IgnoreRoute("{filename}.ashx");

I added this to my <httpHandlers> node in my web config:

<add verb="*" path="*ImgHandler.ashx" type="AMSignsUI.Views.Shared.ImgHandler, AMSignsUI"/>

where : AMSignsUI.Views.Shared = the namespace in which I created the handler

and AMSignsUI = my application/project name

I added this to my <handlers> node in <system.webServer>

<add name="ImgHandler" path="*ImgHandler.ashx" verb="*" type="AMSignsUI.Views.Shared.ImgHandler, AMSignsUI"/>

Everything worked fine after I completed these steps. Note, the last step applies only if you are using IIS7