A simple Orchard module to inject a diagnostics shape into every page of your Orchard site

Orchard has some great extensibility hooks. This post will show you how to very quickly use one to add a diagnostic section (like below) to the top of each page.

This uses:

• A feature in a module: to toggle on/off the ability
• A class implementing Orchards FilterProvider
• A view file to be used as a shape

First thing to do is create a new module, with a feature inside. If you need a primer, try the Orchard Walkthrough and the Hello World Module example. This article assumes that you create a module called "MyModule", and that you make a feature called "MyModule.SessionChecker"

To write output to every page we can hook into the FilterProvider class provided by the Orchard framework. Orchard.Mvc.Filters.FilterProvider is an abstract class that implements IDependency. This means that if your feature implements the class, it will automatically be wired up by Orchard at run time. All you need to do is fill in the methods of the class in your own inherited version, like below.

Code:

    [OrchardFeature("MyModule.SessionChecker")]
    public class SessionCheckerFilter : FilterProvider, IResultFilter
    {
        private readonly IWorkContextAccessor _workContextAccessor;
        private readonly IShapeFactory _shapeFactory;

        public SessionCheckerFilter(IWorkContextAccessor workContextAccessor, IShapeFactory shapeFactory)
        {
            _workContextAccessor = workContextAccessor;
            _shapeFactory = shapeFactory;
        }

        public void OnResultExecuting(ResultExecutingContext filterContext)
        {
            if (filterContext.Result as ViewResult == null) {
                return;
            }

            _workContextAccessor.GetContext(filterContext).Layout.Zones["Body"].Add(_shapeFactory.Create("diagnosticview"), ":before");
        }

        public void OnResultExecuted(ResultExecutedContext filterContext) { }
    }

The key things we are doing here are

• Using the OnResultExecuting method to ensure we hook in as the result is being formed
• Creating a new shape and returning it inside the body zone of the page 

The use of shapes is a massive topic in Orchard, and there are others out there better suited to talking about them. For this purpose it is enough to say that we use the IShapeFactory to create an arbitrary shape. The name of this shape is the name of a razor view that we need to create in our views folder in the module.

Add the file diagnosticsview.cshtml to the "views" folder in your module. The shape factory will find and use this shape. I've made my example as follows:

 <style> 
   .SessionChecker {  
     position:absolute;  
     left:0px;  
     top:0px;  
     z-index:100;  
     border:solid 1pt #AAAAAA;  
     background-color: #EEEEEE;  
     padding: 5px;  
     font-family: consolas, arial;  
     font-size: 10pt;  
   }  
   .SessionChecker b {  
     font-weight: bold;  
   }  
 </style>
 <div class="SessionChecker">  
   Current Value for Session["TestSessionManagement"]: @Session["TestSessionManagement"]  
 </div>  

And all this does is show the value of a particular session setting I'm interested in, but you could make yours much more interesting. Any loigic more complex than that shown should be done within the FilterProvider class you implemented, and be passed to the view as a model

Lastly, make sure to enable your module/feature to see the results. When you don't want them appearing any more, disable the module! Excellent for temporary diagnostic scenarios. For added bonus - only show it when the current user is an admin!

Gotcha in Orchard CMS RoutesDescriptor when using Multi-Tenancy

It's been a while since I posted, and I've been using Orchard CMS a lot among other things. I came across a rather trickysome problem today, hopefully this post will help others find the resolution quicker than I did. In orchard you can Implement IRouteProvider in any module you write. This is basically a wrapper for MVC routes, and works really well. For example, the route defined below is for custom handling in the event of errors.

---

public class ErrorHandlingRoutesProvider : IRouteProvider
    { 
        public IEnumerable<routedescriptor> GetRoutes() 
        { 
            return new[]{  
                new RouteDescriptor{ 
                    Name = "ErrorRoute",  
                    Priority = 1,                     
                    Route = new Route( 
                        "Error", 
                        new RouteValueDictionary{ 
                            {"action", "ErrorPage"}, 
                            {"controller", "ErrorHandler"}, 
                            {"area", "BG.Shared.ErrorHandling"} 
                        }, 
                        new RouteValueDictionary(),//constraints (none here) 
                        new RouteValueDictionary{ 
                            {"area", "BG.Shared.ErrorHandling"} 
                        }, 
                        new MvcRouteHandler()) 
                }; 
        }

---

This works as intended in a single site. However, when you have two tenants using the same module, this will fail with an error similar to the following:

---

System.ArgumentException: A route named 'ErrorRoute' is already in the route collection. Route names must be unique.
Parameter name: name 
   at System.Web.Routing.RouteCollection.Add(String name, RouteBase item) 
   at Orchard.Mvc.Routes.RoutePublisher.Publish(IEnumerable`1 routes) in d:\Workspaces\GitHub\src\Orchard\Mvc\Routes\RoutePublisher.cs:line 100
   at Orchard.Environment.DefaultOrchardShell.Activate() in d:\Workspaces\GitHub\src\Orchard\Environment\DefaultOrchardShell.cs:line 48
   at Orchard.Environment.DefaultOrchardHost.ActivateShell(ShellContext context) in d:\Workspaces\GitHub\src\Orchard\Environment\DefaultOrchardHost.cs:line 156
   at Orchard.Environment.DefaultOrchardHost.CreateAndActivateShells() in d:\Workspaces\GitHub\src\Orchard\Environment\DefaultOrchardHost.cs:line 135

---

The workaround is to comment out the "Name" attribute of the RouteDescriptor, as follows

public IEnumerable<RouteDescriptor> GetRoutes() 
        { 
            return new[]{  
                new RouteDescriptor{ 
                     
                    //Name = "ErrorRoute", //This doesn't work in Multi-Tenancy 
                    Priority = 1,                     
                    Route = new Route( 
                        "Error", 
                        new RouteValueDictionary{ 
                            {"action", "ErrorPage"}, 
                            {"controller", "ErrorHandler"}, 
                            {"area", "BG.Shared.ErrorHandling"} 
                        }, 
                        new RouteValueDictionary(),//constraints (none here) 
                        new RouteValueDictionary{ 
                            {"area", "BG.Shared.ErrorHandling"} 
                        }, 
                        new MvcRouteHandler()) 
                }      
            }; 
        }

I've started investigating this with the Orchard team, but the workaround doesn't really appear to have any drawbacks.