Skip to main content

MVC 3 - Custom view load based on the source of the request

Pornim de la următoarea problema:
Se da o aplicație ASP MVC 3. Se dorește sa încarce view-uri custom pentru fiecare tip de device care o accesează. De exemplu în cazul în care request-ul vine de la un iPhone sau un Windows Phone 7 atunci view-urile care se încarcă o sa fie diferite.
MVC suporta deja crearea unei versiuni de view pentru mobile device, dar acest lucru nu o sa ne fie de ajuns. In funcție de rezoluție sau de brower o sa dorim sa încărcam view-uri total diferite. Informațiile despre ce tip de device accesează resursa le putem găsii in user-agent.
Proprietatea user agent-ul se poate găsii în următoarea locație
HttpContext.Request.UserAgent
Aceasta valoare o sa fie de tip string, unde este necesar sa cautam manual valoarea pe noi o cautam. Pentru IPhone user agent-ul o sa aibe valoarea:
Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1A543a Safari/419.3
Iar un request de la un Windows Phone 7 o sa aibe următoarea valoare:
Mozilla/4.0 (compatible; MSIE 7.0; Windows Phone OS 7.0; Trident/3.1; IEMobile/7.0) Asus;Galaxy6
Sa presupunem ca o sa avem următoarea structura de fișiere sub directorul Views
Views
Home // Nume control
Index.cshtml
IPhone
Index.cshtml
WF7
Index.cshtml
Pentru a definii maparea la views-uri astfel încît sa fie rezolvate cu view-ul dorit este nevoie sa implementam interfața IViewEngine și sa ne definim un ViewEngine custom. In cadrul acestui ViewEngine pe metodele FindPartialView si FindView o sa fie nevoie sa verificam dacă user agent-ul este de la un anumit agent. In cazul în care request-ul vine de la un anumit device custom atunci este nevoie sa transmitem path-ul unde se găsește view-ul respectiv.
Altfel ajunge sa returnam o instanta noua a ViewEngineResult. Deoarece aceasta nu o sa conțină nici un view găsit, căutarea se va face in continuare în alt ViewEngine din colecție.
public class ApplePhoneViewEngine : IViewEngine
{
...
public ViewEngineResult FindPartialView(ControllerContext context, string viewName, bool useCache)
{
return context.HttpContext.Request.UserAgent.StartWith("iPhone)
? BaseViewEngine.FindPartialView(context, "IPhone/" + viewName, false)
: new ViewEngineResult(new string[] { });
}
...
}
Ne-a mai rămas sa înregistram view engine-ul pe care noi l-am definit mai sus. In Application_Start din Global.asax.cs este nevoie sa adaugăm următorul cod:
ViewEngines.Engines.Add(new ApplePhoneViewEngine());
Codul se poate refactoriza destul de frumos, dar va las pe voi sa faceți acest lucru. Daca doriți sa aflați mai multe informații puteți sa aruncați o privire aici: https://raw.github.com/gist/1077436/a35a62ce4be85ab439dacf44205792ca9ff2791d/customviewengine.cs

Comments

  1. MVC 4 are asa ceva... si e developer preview

    ReplyDelete
  2. Am vazut, dar pana atunci ne descurcam cu ce avem, sunt multumit si cu MVC 3.

    ReplyDelete

Post a Comment

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

Azure AD and AWS Cognito side-by-side

In the last few weeks, I was involved in multiple opportunities on Microsoft Azure and Amazon, where we had to analyse AWS Cognito, Azure AD and other solutions that are available on the market. I decided to consolidate in one post all features and differences that I identified for both of them that we should need to take into account. Take into account that Azure AD is an identity and access management services well integrated with Microsoft stack. In comparison, AWS Cognito is just a user sign-up, sign-in and access control and nothing more. The focus is not on the main features, is more on small things that can make a difference when you want to decide where we want to store and manage our users.  This information might be useful in the future when we need to decide where we want to keep and manage our users.  Feature Azure AD (B2C, B2C) AWS Cognito Access token lifetime Default 1h – the value is configurable 1h – cannot be modified

What to do when you hit the throughput limits of Azure Storage (Blobs)

In this post we will talk about how we can detect when we hit a throughput limit of Azure Storage and what we can do in that moment. Context If we take a look on Scalability Targets of Azure Storage ( https://azure.microsoft.com/en-us/documentation/articles/storage-scalability-targets/ ) we will observe that the limits are prety high. But, based on our business logic we can end up at this limits. If you create a system that is hitted by a high number of device, you can hit easily the total number of requests rate that can be done on a Storage Account. This limits on Azure is 20.000 IOPS (entities or messages per second) where (and this is very important) the size of the request is 1KB. Normally, if you make a load tests where 20.000 clients will hit different blobs storages from the same Azure Storage Account, this limits can be reached. How we can detect this problem? From client, we can detect that this limits was reached based on the HTTP error code that is returned by HTTP