I am creating an ActionResult in ASP.Net MVC to serve images. With Session state enabled, IIS will only handle one request at a time from the same user. (This is true not just in MVC.)
Therefore, on a page with multiple images calling back to this Action, only one image request can be handled at a time. It's synchronous.
I'd like this image Action to be asynchronous -- I'd like multiple image requests to each execute without needing the previous one to complete. (If the images were just static files, IIS would serve them up this way.)
So, I'd like to disable Session just for calls to that Action, or to specify that certain requests do not have Session state. Anyone know how this is done in MVC? Thanks!
If anyone is in the situation I was in, where your image controller actually needs read only access to the session, you can put the SessionState attribute on your controller
[SessionState(SessionStateBehavior.ReadOnly)]
See http://msdn.microsoft.com/en-us/library/system.web.mvc.sessionstateattribute.aspx for more info.
Thanks to https://stackoverflow.com/a/4235006/372926
Rather than implementing an action filter for this, why don't you implement a RouteHandler?
Here's the deal - IRouteHandler has one method - GetHttpHandler. When you make an ASP.Net MVC request to a controller, by default the routing engine handles the request by creating a new instance of MvcRouteHandler, which returns an MvcHandler. MvcHandler is an implementation of IHttpHandler which is marked with the (surprise!) IRequiresSessionState interface. This is why a normal request uses Session.
If you follow my blog post on how to implement a custom RouteHandler (instead of using MvcRouteHandler) for serving up images - you can skip returning a session-tagged IHttpHandler.
This should free IIS from imposing synchronicity on you. It would also likely be more performant because it's skipping all the layers of the MVC code dealing with filters.
I also came across the same problem and after doing R&D this link worked for me
Reference:
https://techatfingers.wordpress.com/2016/06/14/session-state-on-action/
Create custom Attribute
Override the “GetControllerSessionBehavior” method present in class DefaultControllerFactory.
Register it in global.aspx
1> Create custom Attribute
public sealed class ActionSessionStateAttribute : Attribute
{
public SessionStateBehavior SessionBehavior { get; private set; }
public ActionSessionStateAttribute(SessionStateBehavior sessionBehavior)
{
SessionBehavior = sessioBehavior;
}
}
2. Override
public class SessionControllerFactory : DefaultControllerFactory
{
protected override SessionStateBehavior GetControllerSessionBehavior(RequestContext requestContext, Type controllerType)
{
if (controllerType == null)
return SessionStateBehavior.Default;
var actionName = requestContext.RouteData.Values["action"].ToString();
Type typeOfRequest=requestContext.HttpContext.Request.RequestType.ToLower() =="get"?typeof(HttpGetAttribute):typeof(HttpPostAttribute);
// [Line1]
var cntMethods = controllerType.GetMethods()
.Where(m =>
m.Name == actionName &&
( ( typeOfRequest == typeof(HttpPostAttribute) &&
m.CustomAttributes.Where(a => a.AttributeType == typeOfRequest).Count()>0
)
||
( typeOfRequest == typeof(HttpGetAttribute) &&
m.CustomAttributes.Where(a => a.AttributeType == typeof(HttpPostAttribute)).Count() == 0
)
)
);
MethodInfo actionMethodInfo = actionMethodInfo = cntMethods != null && cntMethods.Count() == 1 ? cntMethods.ElementAt(0):null;
if (actionMethodInfo != null)
{
var sessionStateAttr = actionMethodInfo.GetCustomAttributes(typeof(ActionSessionStateAttribute), false)
.OfType<ActionSessionStateAttribute>()
.FirstOrDefault();
if (sessionStateAttr != null)
{
return sessionStateAttr.Behavior;
}
}
return base.GetControllerSessionBehavior(requestContext, controllerType);
}
3. Register class in Global.asax
public class MvcApplication : System.Web.HttpApplication
{
protected void Application_Start()
{
// --- other code ---
ControllerBuilder.Current.SetControllerFactory(typeof(SessionControllerFactory));
}
}
Try serving the images from another domain. So something like images.mysite.com.
This will provide you two benefits: One, sessions are tracked by a cookie, so images.mysite.com won't have the cookie. Two, it will give you an additional two concurrent requests to retrieve images.
Have you considered setting up a HttpHandler to serve up your images?
SessionState attribute is quite helpful if u use mvc3. How to achieve this with mvc2 needs a little more coding.
Idea is to tell the asp.net that specific request wont use session object.
So, Create a custom route handler for specific requests
public class CustomRouteHandler : IRouteHandler
{
public System.Web.IHttpHandler GetHttpHandler(RequestContext requestContext)
{
requestContext.HttpContext.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.ReadOnly);
return new MvcHandler(requestContext);
}
}
SessionStateBehavior enum has 4 members, you should use "disabled" or "readonly" modes to get async behavior.
After creating this custom route handler, be sure that your specific requests goes through this handler. This can be done via defining new routes at Global.asax
routes.Add("Default", new Route(
"{controller}/{action}",
new RouteValueDictionary(new { controller = "Home", action = "Index"}),
new CustomRouteHandler()
));
Adding this route makes all your requests to be handled by your custom route handler class. You can make it specific by defining different routes.
Change DefaultCOntrollerFactory to custom ControllerFactory class. Default Controller.TempDataProvider use SessionStateTempDataProvider. you can change it.
1.Set web.config/system.web/sessionState:mode="Off".
2.create DictionaryTempDataProvider class.
public class DictionaryTempDataProvider : ITempDataProvider
{
public IDictionary<string, object> LoadTempData(ControllerContext controllerContext)
{
return new Dictionary<string, object>();
}
public void SaveTempData(ControllerContext controllerContext, IDictionary<string, object> values)
{
}
}
3.Create DictionaryTempDataControllerFactory
public class DictionaryTempDataControllerFactory : DefaultControllerFactory
{
public override IController CreateController(System.Web.Routing.RequestContext requestContext, string controllerName)
{
var controller = base.CreateController(requestContext, controllerName) as Controller;
if (controller!=null)
controller.TempDataProvider = new DictionaryTempDataProvider();
return controller;
}
}
4.In global.asax.cs Apprication_Start event set DictionaryTempDataControllerFactory.
protected void Application_Start()
{
RegisterRoutes(RouteTable.Routes);
ControllerBuilder.Current.SetControllerFactory(
new DictionaryTempDataControllerFactory()
);
}
On our server, IIS doesn't even know about sessions - it's the ASP.NET stack that handles one request per session at a time. Static files, like images, are never affected.
Is it possible that your ASP.NET app is serving the files instead of IIS?
Create new Controller
Decorate controler with [SessionState(SessionStateBehavior.Disabled)]
Refactor code you want seesion stated disabled for to that controller
I would to share my solution for disable ASP.NET Session for an specific request (in my case, a WCF Service) using an HttpModule:
public class AspNetSessionFilterModule : IHttpModule
{
public void Init(HttpApplication context)
{
context.PostMapRequestHandler += OnPostMapRequestHandler;
}
private void OnPostMapRequestHandler(object sender, EventArgs e)
{
var context = (sender as HttpApplication).Context;
DisableSessionForSomeRequests(context);
}
private void DisableSessionForSomeRequests(HttpContext context)
{
if ("~/Services/MyService.svc".Equals(context.Request.AppRelativeCurrentExecutionFilePath, StringComparison.InvariantCultureIgnoreCase))
{
context.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.Disabled);
}
}
public void Dispose()
{ }
}
Related
I have a bit of problem
I have an MVC site that is working just fine.
I wanted to have SEO friendly urls so I created custom routing that looks like this
{section}/{group}/{manufacturer}
since it has the same number of fields as the default route
{controller}/{action}/{id}
i created in loop in RouteConfig.cs that goes to database and loops Sections table and creates custom routes like
FOOD/{group}/{manufacturer}
SPORT/{group}/{manufacturer}
CARS/{group}/{manufacturer}
and point it to the Sections controller.
It works just fine. The problem I have is that now i need to rename FOOD to FRESH-FOOD and i want to keep old links to FOOD working.
What would you recommend ? How can I solve this ?
Is there a better way to do route Section instead of custom routes ?
Sounds like this might be a good case for a custom route handler. In the ProcessRequest method below you can check for controller name of "FOOD" and redirect to "FRESH-FOOD" like this:
public class CustomRouteHandler : IRouteHandler
{
public IHttpHandler GetHttpHandler(RequestContext requestContext)
{
return new CustomHttpHandler();
}
}
public class CustomHttpHandler : IHttpHandler
{
public bool IsReusable
{
get
{
return true;
}
}
public void ProcessRequest(HttpContext context)
{
var routeValues = context.Request.RequestContext.RouteData.Values;
var controllerName = context.Request.RequestContext.RouteData.GetRequiredString("controller");
if (controllerName.ToLower() == "food") controllerName = "FRESH-FOOD";
var controller = ControllerBuilder.Current.GetControllerFactory().
CreateController(context.Request.RequestContext, controllerName);
if (controller != null)
{
controller.Execute(context.Request.RequestContext);
}
}
}
When you create your custom routes use the Route constructor overload that takes an IRouteHandler
I'm new to MVC (5). In order to add localization support to my website I added a "Language" field to my ApplicationUser : IdentityUser
What's the best approach to now store this information in the browser and ensure that it gets re-created even if the user manually deletes it?
TL; but I've got time
What I've tried until now:
I started creating a cookie in my method private async Task SignInAsync(ApplicationUser user, bool isPersistent) but I notice that:
This method is not used if the user is already authenticated and automatically logs in using the .Aspnet.Applicationcookie and my language cookie could be meanwhile expired (or been deleted).
A user could manually delete the cookie, just for fun.
I thought about checking its existence in the controller (querying the logged user and getting it from the db) and it works but I'd need to do it in EVERY controller. I'm not sure is the correct way to do this.
Any suggestion about how to approach this problem and guarantee that the application has a valid "language cookie" on every request?
It sounds to me like what you want here is a Custom Action Filter. You can override the OnActionExecuting method which means the logic is run before any action is called
public class EnsureLanguagePreferenceAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
var langCookie = filterContext.HttpContext.Request.Cookies["LanguagePref"];
if (langCookie == null)
{
// cookie doesn't exist, either pull preferred lang from user profile
// or just setup a cookie with the default language
langCookie = new HttpCookie("LanguagePref", "en-gb");
filterContext.HttpContext.Request.Cookies.Add(langCookie);
}
// do something with langCookie
base.OnActionExecuting(filterContext);
}
}
Then register your attribute globally so it just becomes the default behaviour on every controller action
public static void RegisterGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new HandleErrorAttribute());
filters.Add(new EnsureLanguagePreferenceAttribute());
}
To me, the easiest way would be to create your own Authorize attribute (since your language options are tied to an authenticated user account). Inside of your new authorize attribute, simply perform the check if the cookie exists. If it does, then life is good. Else, query the user's database profile and reissue the cookie with the stored value
public class MyAuthorization : AuthorizeAttribute
{
protected override bool AuthorizeCore(HttpContextBase httpContext)
{
//no point in cookie checking if they are not authorized
if(!base.AuthorizeCore(httpContext)) return false;
var cookie = httpContext.Request.Cookies["LanguageCookie"];
if (cookie == null) {
CreateNewCookieMethod();
}
return true;
}
}
To use, replace [Authorize] with [MyAuthorization] in your project.
If you don't want to mess with the [Authorize] attribute, you could create your own attribute that does the cookie checking and decorate your controller with that one as well.
One last alternative is to create your own Controller class that does the checking on the OnActionExecuting.
public class MyBaseController : Controller
{
public string Language {get;set;}
protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
var cookie = filterContext.HttpContext.Request.Cookies["LanguageCookie"];
if(cookie == null){
cookie = CreateNewCookieMethod();
filterContext.HttpContext.Request.Cookies.Add(cookie);
}
Language = cookie.Value;
base.OnActionExecuting(filterContext);
}
How to use (note that we inherit from MybaseController now)
public class HomeController : MyBaseController{
public ActionResult Index(){
//Language comes from the base controller class
ViewBag.Language = Language;
Return View();
}
}
This method is neat because now that Language variable will be available in any controller that inherits from this new class.
Either of these will give you a single, cookie checking point. Additionally, you are only going back to the database only in the instance that the cookie does not exist.
I have an mvc 3 app for which I'm implementing authorization using my own login view which checks if the users name and password are allowed and then sets a variable in the session to say that the user is loggged in. This kind of works but for one particular view it is behaving in a strange undesirable way. The said view contains a form which I use to input some data and upload a file. For some reason which I can't figure out, after this form is posted a new session is started and therefore the variable which remembered that the user was logged in is reset to false and subsequently the login page is displayed again.
I'm lost as to why the application is starting a new session at this point? I have not instructed it to do this. Can anyone recommend solutions to stop this behaviour and get it to keep the old session?
Thanks.
UPDATE - Some Code:
Note the session seems to be terminated immediately after the response to the posted Create form
CMS controller which uses a custom Autorize attribute called "RDAutorize" on all actions:
[RDAuthorize]
public class PhotoCMSController : Controller
{
public ActionResult Create()
{
/* Code omitted: set up a newPhoto object with default state */
/* Display view containing form to upload photo and set title etc. */
return View("../Views/PhotoCMS/Create", newPhoto);
}
[HttpPost]
public ContentResult Upload(int pPhotoId)
{
/* Code ommited: receive and store image file which was posted
via an iframe on the Create view */
string thumbnail = "<img src='/path/to/thumb.jpg' />";
return Content(thumbnail);
}
[HttpPost]
public ActionResult Create(string pPhotoTitle, string pCaption etc...)
{
/*Code omitted: receive the rest of the photo data and save
it along with a reference to the image file which was uploaded
previously via the Upload action above.*/
/* Display view showing list of all photo records created */
return View("../Views/PhotoCMS/Index", qAllPhotos.ToList<Photo>());
/* **Note: after this view is returned the Session_End() method fires in
the Global.asax.cs file i.e. this seems to be where the session is
being lost** */
}
}/*End of CMS Controller*/
Custom Authorize action filter:
public class RDAuthorize : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
Boolean authorized = Convert.ToBoolean(
HttpContext.Current.Session["UserIsAuthorized"]
);
if (!authorized) {
/* Not logged in so send user to the login page */
filterContext.HttpContext.Response.Redirect("/Login/Login");
}
}
public override void OnActionExecuted(ActionExecutedContext filterContext) {}
public override void OnResultExecuting(ResultExecutingContext filterContext) {}
public override void OnResultExecuted(ResultExecutedContext filterContext) {}
}/*End of Authorize Action Filter*/
Login controller:
public class LoginController : Controller
{
private PhotoDBContext _db = new PhotoDBContext();
public ActionResult Login()
{
string viewName = "";
Boolean authorized = Convert.ToBoolean(Session["UserIsAuthorized"]);
if (authorized)
{
viewName = "../Views/Index";
}
else
{
viewName = "../Views/Login/Login";
}
return View(viewName);
}
[HttpPost]
public ActionResult Login(string pUsername, string pPassword)
{
string viewName = "";
List<Photo> model = new List<Photo>();
var qUsers = from u in _db.Users
select u;
foreach (User user in qUsers.ToList<User>())
{
/* If authorized goto CMS pages */
if (pUsername == user.Username && pPassword == user.Password)
{
Session["UserIsAuthorized"] = true;
var qPhotos = from p in _db.Photos
where p.IsNew == false
select p;
model = qPhotos.ToList<Photo>();
viewName = "../Views/PhotoCMS/Index";
break;
}
}
return View(viewName, model);
}
}/* End of Login controller */
Turns out the whole ASP.Net application was restarting because as part of the photo upload I was storing the image file in a temporary folder and then deleting the directory after moving the file to a permanent location. Apparently its default behaviour for ASP.Net to restart if a directory within the web site is deleted. I found this post
which describes the problem and offers a solution whereby the following code is added to the Global.asax.cs file. Implementing this solution has fixed the problem. The fix is applied by calling FixAppDomainRestartWhenTouchingFiles() from the Application_Start() event:
protected void Application_Start()
{
FixAppDomainRestartWhenTouchingFiles();
}
private void FixAppDomainRestartWhenTouchingFiles()
{
if (GetCurrentTrustLevel() == AspNetHostingPermissionLevel.Unrestricted)
{
/*
From: http://www.aaronblake.co.uk/blog/2009/09/28/bug-fix-application-restarts-on-directory-delete-in-asp-net/
FIX disable AppDomain restart when deleting subdirectory
This code will turn off monitoring from the root website directory.
Monitoring of Bin, App_Themes and other folders will still be
operational, so updated DLLs will still auto deploy.
*/
PropertyInfo p = typeof(HttpRuntime).GetProperty(
"FileChangesMonitor", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Static);
object o = p.GetValue(null, null);
FieldInfo f = o.GetType().GetField(
"_dirMonSubdirs", BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.IgnoreCase);
object monitor = f.GetValue(o);
MethodInfo m = monitor.GetType().GetMethod(
"StopMonitoring", BindingFlags.Instance | BindingFlags.NonPublic);
m.Invoke(monitor, new object[] { });
}
}
private AspNetHostingPermissionLevel GetCurrentTrustLevel()
{
foreach (AspNetHostingPermissionLevel trustLevel in
new AspNetHostingPermissionLevel[] {
AspNetHostingPermissionLevel.Unrestricted,
AspNetHostingPermissionLevel.High,
AspNetHostingPermissionLevel.Medium,
AspNetHostingPermissionLevel.Low,
AspNetHostingPermissionLevel.Minimal }
)
{
try
{
new AspNetHostingPermission(trustLevel).Demand();
}
catch (System.Security.SecurityException)
{
continue;
}
return trustLevel;
}
return AspNetHostingPermissionLevel.None;
}
Since sessions are associated with cookies, they are available for a specific domain.
It's a common mistake to ask for a session variable in the same application while the domain has changed (i.e. redirecting to a subdomain).
Does the controller action that you are posting the form contains any [Authorize] attribute. You need to post some code.
Verify a new session is really started every time. Check Trace output for the user's session id to ensure it realllly has changed.
Ensure the cookie getting sent over is actually getting set and sent over. (called ASPsessionIDSOMETHING ) and if that is being sent by the browser. Download the tool Fiddler to check the cookies easily (set cookie header coming from the server and the request cookies going back to the server from the browser. Make sure your browser is accepting the cookie and you dont say... have cookies turned off.
If your session id is changing at every request then your session isn't properly getting set the first time, set a break point on that code if you havent already.
You can log when the worker process resets - ensure that isn't the case. see http://www.microsoft.com/technet/prodtechnol/windowsserver2003/library/IIS/87892589-4eda-4003-b4ac-3879eac4bf48.mspx
I had the same problem. The problem only occured when a post request was send to the server and the session was not modified during that request. What I did as a workaround was, to write a custom filter which does nothing more than writing a key / value into the session on each request and added that filter to the GlobalFilter collection in the global.asax.
public class KeepSessionAlive : IActionFilter
{
public void OnActionExecuting(ActionExecutingContext filterContext)
{
if(filterContext.HttpContext.Session != null)
{
filterContext.HttpContext.Session["HeartBeat"] = DateTime.Now.ToShortDateString();
}
}
public void OnActionExecuted(ActionExecutedContext filterContext) { }
}
And in the global.asax:
protected override void AddCustomGlobalFilters(GlobalFilterCollection filters)
{
filters.Add(new KeepSessionAlive());
}
This might be not the best solution but it helped me in my case.
I have the pattern User/{domain}/{username} set up via Routing. Everything works except for one thing. I can't figure out how to get the domain and username variables passed to my redirected page. Below is my GetHttpHandler method from my IRouteHandler implementation.
public IHttpHandler GetHttpHandler(RequestContext requestContext)
{
string basePath;
basePath = "~/UserPage.aspx";
string domain = requestContext.RouteData.GetRequiredString("domain");
string username = requestContext.RouteData.GetRequiredString("username");
string virtualPath =
string.Format(basePath + "?domain={0}&username={1}", domain, username);
return (Page)BuildManager.CreateInstanceFromVirtualPath(virtualPath, typeof(Page));
}
I get the error from the last line of code:
UserPage.aspx?domain=SOMEDOMAIN&username=SOMEUSER is not a valid virtual path.
So how are you supposed to pass variables to the target page? what am I missing?
I think I solved this one myself.
Found this loop
foreach (KeyValuePair<string, object> token in requestContext.RouteData.Values)
{
requestContext.HttpContext.Items.Add(token.Key, token.Value);
}
from http://www.codethinked.com/post/2008/08/20/Exploring-SystemWebRouting.aspx
Its like the 4th code sample down.
UPDATE:
Not sure if this will work... requestContext.HttpContext seems to be "readonly". Back to the drawing board.
UPDATE 2:
Looks like this will work if you add in a reference to System.Web.Abstractions
Started mucking around with things and saw the IHttpHandler interface provides the RequestContext to the GetHttpHandler method.
So, I modified my base page class (I always put a layer between System.Web.UI.Page and my own pages, calling it BasePage or similar just for the purpose). So I added a public property on PVBasePage to receive a RequestContext object.
public RequestContext RequestContext { get; set; }
Then, my Routing class code is as follows:
IHttpHandler IRouteHandler.GetHttpHandler(RequestContext requestContext)
{
// create the page object as my own page...
var page = BuildManager.CreateInstanceFromVirtualPath(VirtualPath
, typeof(PVBasePage)) as PVBasePage;
// pass in the request context
page.RequestContext = requestContext;
// return this page in the form of a IHttpHandler
return page as IHttpHandler;
}
So instead of, as in the sample code, creating the instance directly as the IHttpHandler, I create it as my own page. Set the request context property, and then return the page to the caller AS a IHttpHandler.
Tested and it works. WOO HOO!
Then in the instance page, you can hit the RequestContext.GetValues collection to read out your passed in parameters.
HTH
#B.Tyndall
I just got this working with a solution similar to yours.
found at: http://msmvps.com/blogs/luisabreu/archive/2008/03/12/using-the-routing-mvc-api-with-classic-asp-net.aspx
foreach (var aux in requestContext.RouteData.Values)
{
HttpContext.Current.Items[aux.Key] = aux.Value;
}
So in effect you're no longer using the Request.QueryString but instead Context.Items collection
HttpContext.Current.Items["RouteName"]
or
Context.Items["RouteName"]
It appears as though other are also taking the route (no pun intended) of putting the parameters in the context Items collection.
http://bbits.co.uk/blog/archive/2008/05/19/using-asp.net-routing-independent-of-mvc---passing-parameters-to.aspx
I combined a couple of these approaches for pages that have a specific parameter, I created a UserNameRouteHandler for pages that accept that type of parameter. In my PageBase class I checked the context items for that parameter and then set a property so that my pages that inherit from PageBase can use it.
public class UserNameRouteHandler : IRouteHandler
{
#region Implementation of IRouteHandler
public IHttpHandler GetHttpHandler(RequestContext requestContext)
{
string pageName = requestContext.RouteData.GetRequiredString("PageName");
string employeeUserName = requestContext.RouteData.GetRequiredString("UserName");
if(!string.IsNullOrEmpty(employeeUserName))
{
requestContext.HttpContext.Items["UserName"] = employeeUserName;
}
pageName = pageName.ToLower() == "home" ? "default" : pageName;
string virtualPath = string.Format("~/{0}.aspx", pageName);
return (Page)BuildManager.CreateInstanceFromVirtualPath(virtualPath, typeof(Page));
}
#endregion
}
And in my OnLoad of PageBase I set the property to pages that need it can have it...definitely looking for a more elegant solution though.
protected override void OnLoad(EventArgs e)
{
if (!IsPostBack)
{
if (Context.Items["UserName"] != null)
{
EmployeeUserName = Context.Items["UserName"].ToString();
}
}
base.OnLoad(e);
}
I am trying to work out a way to use dependency injection with ASP.NET Web Forms controls.
I have got lots of controls that create repositories directly, and use those to access and bind to data etc.
I am looking for a pattern where I can pass repositories to the controls externally (IoC), so my controls remain unaware of how repositories are constructed and where they come from etc.
I would prefer not to have a dependency on the IoC container from my controls, therefore I just want to be able to construct the controls with constructor or property injection.
(And just to complicate things, these controls are being constructed and placed on the page by a CMS at runtime!)
Any thoughts?
UPDATE 2019:
With the introduction of Web Forms 4.7.2, there is now better support for DI. This invalidates the below. See: Wiring up Simple Injector in WebForms in .NET 4.7.2
You can use automatic constructor injection by replacing the default PageHandlerFactory with a custom one. This way you can use an overloaded constructor to load the dependencies. Your page might look like this:
public partial class HomePage : System.Web.UI.Page
{
private readonly IDependency dependency;
public HomePage(IDependency dependency)
{
this.dependency = dependency;
}
// Do note this protected ctor. You need it for this to work.
protected HomePage () { }
}
Configuring that custom PageHandlerFactory can be done in the web.config as follows:
<?xml version="1.0"?>
<configuration>
<system.web>
<httpHandlers>
<add verb="*" path="*.aspx"
type="YourApp.CustomPageHandlerFactory, YourApp"/>
</httpHandlers>
</system.web>
</configuration>
Your CustomPageHandlerFactory can look like this:
public class CustomPageHandlerFactory : PageHandlerFactory
{
private static object GetInstance(Type type)
{
// TODO: Get instance using your favorite DI library.
// for instance using the Common Service Locator:
return Microsoft.Practices.ServiceLocation
.ServiceLocator.Current.GetInstance(type);
}
public override IHttpHandler GetHandler(HttpContext cxt,
string type, string vPath, string path)
{
var page = base.GetHandler(cxt, type, vPath, path);
if (page != null)
{
// Magic happens here ;-)
InjectDependencies(page);
}
return page;
}
private static void InjectDependencies(object page)
{
Type pageType = page.GetType().BaseType;
var ctor = GetInjectableCtor(pageType);
if (ctor != null)
{
object[] arguments = (
from parameter in ctor.GetParameters()
select GetInstance(parameter.ParameterType)
.ToArray();
ctor.Invoke(page, arguments);
}
}
private static ConstructorInfo GetInjectableCtor(
Type type)
{
var overloadedPublicConstructors = (
from constructor in type.GetConstructors()
where constructor.GetParameters().Length > 0
select constructor).ToArray();
if (overloadedPublicConstructors.Length == 0)
{
return null;
}
if (overloadedPublicConstructors.Length == 1)
{
return overloadedPublicConstructors[0];
}
throw new Exception(string.Format(
"The type {0} has multiple public " +
"ctors and can't be initialized.", type));
}
}
Downside is that this only works when running your side in Full Trust. You can read more about it here. But do note that developing ASP.NET applications in partial trust seems a lost cause.
Starting from .NET 4.7.2 (what's new), it is now easy for developers to use Dependency Injection in WebForms applications. With the UnityAdapter, you can add it to your existing WebForms application in 4 simple steps. See this blog.
Autofac supports fairly unobtrusive dependency injection in ASP.NET WebForms. My understanding is it just hooks into the ASP.NET page lifecycle using an http module and does property injection. The only catch is that for controls I don't think this happens until after the Init event.
The best way is to have a base class for the controls like:
public class PartialView : UserControl
{
protected override void OnInit(System.EventArgs e)
{
ObjectFactory.BuildUp(this);
base.OnInit(e);
}
}
That will inject any control that inherits from that base class (uses structuremap). Combining that with a property based config, you will be able to have controls like:
public partial class AdminHeader : PartialView
{
IMyRepository Repository{get;set;}
}
Update 1: If you can't have the controls inherit, perhaps the CMS has a hook right after creating the controls, in there you can call the BuildUp. Also if the CMS allows you to hook something to fetch the instance you could use constructor based injection, but I prefer BuildUp on this specific scenario as asp.net doesn't have a hook for this.
You could also create some singleton instances in the Application_Start global.asax event and have them available as public static readonly properties.
This is a solution I recently used to avoid hooking into the pipeline (I find that confuses everyone that looks at my code in the future, but yes, I see its benefits as well):
public static class TemplateControlExtensions
{
static readonly PerRequestObjectManager perRequestObjectManager = new PerRequestObjectManager();
private static WIIIPDataContext GetDataContext(this TemplateControl templateControl)
{
var dataContext = (WIIIPDataContext) perRequestObjectManager.GetValue("DataContext");
if (dataContext == null)
{
dataContext = new WIIIPDataContext();
perRequestObjectManager.SetValue("DataContext", dataContext);
}
return dataContext;
}
public static IMailer GetMailer(this TemplateControl templateControl)
{
return (IMailer)IoC.Container.Resolve(typeof(IMailer));
}
public static T Query<T>(this TemplateControl templateControl, Query<T> query)
{
query.DataContext = GetDataContext(templateControl);
return query.GetQuery();
}
public static void ExecuteCommand(this TemplateControl templateControl, Command command)
{
command.DataContext = GetDataContext(templateControl);
command.Execute();
}
private class PerRequestObjectManager
{
public object GetValue(string key)
{
if (HttpContext.Current != null && HttpContext.Current.Items.Contains(key))
return HttpContext.Current.Items[key];
else
return null;
}
public void SetValue(string key, object newValue)
{
if (HttpContext.Current != null)
HttpContext.Current.Items[key] = newValue;
}
}
}
This shows how you can create your own life time manager pretty easily as well as hook into an IoC container if you so desire. Oh, and I am also using a query/command structure which is sort of unrelated, but more on the reasoning behind that can be found here:
Limit your abstractions: Refactoring toward reduced abstractions