I have a WCF REST service that takes some parameters and sends an email. The template for the email is an MVC3 action. Essentially I want to render that action to a string.
If it were an ASP.NET WebForm, I could simply use Server.Execute(path, stringWriter, false). However when I plug in the path to my action, I get Error executing child request.
I have full access to HttpContext from my service (AspNetCompatibilityRequirementsMode.Allowed).
I know there are other answers out there for rendering actions to strings from within the context of a controller. How do I do this when I'm outside that world, but still on the same server (and, for that matter, in the same app)?
I cobbled together an answer based on several different google searches. It works, but I'm not 100% sure it's as lean as it could be. I'll paste the code for others to try.
string GetEmailText(TemplateParameters parameters) {
// Get the HttpContext
HttpContextBase httpContextBase =
new HttpContextWrapper(HttpContext.Current);
// Build the route data
var routeData = new RouteData();
routeData.Values.Add("controller", "EmailTemplate");
routeData.Values.Add("action", "Create");
// Create the controller context
var controllerContext = new ControllerContext(
new RequestContext(httpContextBase, routeData),
new EmailTemplateController());
var body = ((EmailTemplateController)controllerContext.Controller)
.Create(parameters).Capture(controllerContext);
return body;
}
// Using code from here:
// http://blog.approache.com/2010/11/render-any-aspnet-mvc-actionresult-to.html
public class ResponseCapture : IDisposable
{
private readonly HttpResponseBase response;
private readonly TextWriter originalWriter;
private StringWriter localWriter;
public ResponseCapture(HttpResponseBase response)
{
this.response = response;
originalWriter = response.Output;
localWriter = new StringWriter();
response.Output = localWriter;
}
public override string ToString()
{
localWriter.Flush();
return localWriter.ToString();
}
public void Dispose()
{
if (localWriter != null)
{
localWriter.Dispose();
localWriter = null;
response.Output = originalWriter;
}
}
}
public static class ActionResultExtensions
{
public static string Capture(this ActionResult result, ControllerContext controllerContext)
{
using (var it = new ResponseCapture(controllerContext.RequestContext.HttpContext.Response))
{
result.ExecuteResult(controllerContext);
return it.ToString();
}
}
}
Related
How can I pass along auditing information between clients and services in an easy way without having to add that information as arguments for all service methods? Can I use message headers to set this data for a call?
Is there a way to allow service to pass that along downstream also, i.e., if ServiceA calls ServiceB that calls ServiceC, could the same auditing information be send to first A, then in A's call to B and then in B's call to C?
There is actually a concept of headers that are passed between client and service if you are using fabric transport for remoting. If you are using Http transport then you have headers there just as you would with any http request.
Note, below proposal is not the easiest solution, but it solves the issue once it is in place and it is easy to use then, but if you are looking for easy in the overall code base this might not be the way to go. If that is the case then I suggest you simply add some common audit info parameter to all your service methods. The big caveat there is of course when some developer forgets to add it or it is not set properly when calling down stream services. It's all about trade-offs, as alway in code :).
Down the rabbit hole
In fabric transport there are two classes that are involved in the communication: an instance of a IServiceRemotingClient on the client side, and an instance of IServiceRemotingListener on the service side. In each request from the client the messgae body and ServiceRemotingMessageHeaders are sent. Out of the box these headers include information of which interface (i.e. which service) and which method are being called (and that's also how the underlying receiver knows how to unpack that byte array that is the body). For calls to Actors, which goes through the ActorService, additional Actor information is also included in those headers.
The tricky part is hooking into that exchange and actually setting and then reading additional headers. Please bear with me here, it's a number of classes involved in this behind the curtains that we need to understand.
The service side
When you setup the IServiceRemotingListener for your service (example for a Stateless service) you usually use a convenience extension method, like so:
protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
{
yield return new ServiceInstanceListener(context =>
this.CreateServiceRemotingListener(this.Context));
}
(Another way to do it would be to implement your own listener, but that's not really what we wan't to do here, we just wan't to add things on top of the existing infrastructure. See below for that approach.)
This is where we can provide our own listener instead, similar to what that extention method does behind the curtains. Let's first look at what that extention method does. It goes looking for a specific attribute on assembly level on your service project: ServiceRemotingProviderAttribute. That one is abstract, but the one that you can use, and which you will get a default instance of, if none is provided, is FabricTransportServiceRemotingProviderAttribute. Set it in AssemblyInfo.cs (or any other file, it's an assembly attribute):
[assembly: FabricTransportServiceRemotingProvider()]
This attribute has two interesting overridable methods:
public override IServiceRemotingListener CreateServiceRemotingListener(
ServiceContext serviceContext, IService serviceImplementation)
public override IServiceRemotingClientFactory CreateServiceRemotingClientFactory(
IServiceRemotingCallbackClient callbackClient)
These two methods are responsible for creating the the listener and the client factory. That means that it is also inspected by the client side of the transaction. That is why it is an attribute on assembly level for the service assembly, the client side can also pick it up together with the IService derived interface for the client we want to communicate with.
The CreateServiceRemotingListener ends up creating an instance FabricTransportServiceRemotingListener, however in this implementation we cannot set our own specific IServiceRemotingMessageHandler. If you create your own sub class of FabricTransportServiceRemotingProviderAttribute and override that then you can actually make it create an instance of FabricTransportServiceRemotingListener that takes in a dispatcher in the constructor:
public class AuditableFabricTransportServiceRemotingProviderAttribute :
FabricTransportServiceRemotingProviderAttribute
{
public override IServiceRemotingListener CreateServiceRemotingListener(
ServiceContext serviceContext, IService serviceImplementation)
{
var messageHandler = new AuditableServiceRemotingDispatcher(
serviceContext, serviceImplementation);
return (IServiceRemotingListener)new FabricTransportServiceRemotingListener(
serviceContext: serviceContext,
messageHandler: messageHandler);
}
}
The AuditableServiceRemotingDispatcher is where the magic happens. It is our own ServiceRemotingDispatcher subclass. Override the RequestResponseAsync (ignore HandleOneWay, it is not supported by service remoting, it throws an NotImplementedException if called), like this:
public class AuditableServiceRemotingDispatcher : ServiceRemotingDispatcher
{
public AuditableServiceRemotingDispatcher(ServiceContext serviceContext, IService service) :
base(serviceContext, service) { }
public override async Task<byte[]> RequestResponseAsync(
IServiceRemotingRequestContext requestContext,
ServiceRemotingMessageHeaders messageHeaders,
byte[] requestBodyBytes)
{
byte[] userHeader = null;
if (messageHeaders.TryGetHeaderValue("user-header", out auditHeader))
{
// Deserialize from byte[] and handle the header
}
else
{
// Throw exception?
}
byte[] result = null;
result = await base.RequestResponseAsync(requestContext, messageHeaders, requestBodyBytes);
return result;
}
}
Another, easier, but less flexible way, would be to directly create an instance of FabricTransportServiceRemotingListener with an instance of our custom dispatcher directly in the service:
protected override IEnumerable<ServiceInstanceListener> CreateServiceInstanceListeners()
{
yield return new ServiceInstanceListener(context =>
new FabricTransportServiceRemotingListener(this.Context, new AuditableServiceRemotingDispatcher(context, this)));
}
Why is this less flexible? Well, because using the attribute supports the client side as well, as we see below
The client side
Ok, so now we can read custom headers when receiving messages, how about setting those? Let's look at the other method of that attribute:
public override IServiceRemotingClientFactory CreateServiceRemotingClientFactory(IServiceRemotingCallbackClient callbackClient)
{
return (IServiceRemotingClientFactory)new FabricTransportServiceRemotingClientFactory(
callbackClient: callbackClient,
servicePartitionResolver: (IServicePartitionResolver)null,
traceId: (string)null);
}
Here we cannot just inject a specific handler or similar as for the service, we have to supply our own custom factory. In order not to have to reimplement the particulars of FabricTransportServiceRemotingClientFactory I simply encapsulate it in my own implementation of IServiceRemotingClientFactory:
public class AuditedFabricTransportServiceRemotingClientFactory : IServiceRemotingClientFactory, ICommunicationClientFactory<IServiceRemotingClient>
{
private readonly ICommunicationClientFactory<IServiceRemotingClient> _innerClientFactory;
public AuditedFabricTransportServiceRemotingClientFactory(ICommunicationClientFactory<IServiceRemotingClient> innerClientFactory)
{
_innerClientFactory = innerClientFactory;
_innerClientFactory.ClientConnected += OnClientConnected;
_innerClientFactory.ClientDisconnected += OnClientDisconnected;
}
private void OnClientConnected(object sender, CommunicationClientEventArgs<IServiceRemotingClient> e)
{
EventHandler<CommunicationClientEventArgs<IServiceRemotingClient>> clientConnected = this.ClientConnected;
if (clientConnected == null) return;
clientConnected((object)this, new CommunicationClientEventArgs<IServiceRemotingClient>()
{
Client = e.Client
});
}
private void OnClientDisconnected(object sender, CommunicationClientEventArgs<IServiceRemotingClient> e)
{
EventHandler<CommunicationClientEventArgs<IServiceRemotingClient>> clientDisconnected = this.ClientDisconnected;
if (clientDisconnected == null) return;
clientDisconnected((object)this, new CommunicationClientEventArgs<IServiceRemotingClient>()
{
Client = e.Client
});
}
public async Task<IServiceRemotingClient> GetClientAsync(
Uri serviceUri,
ServicePartitionKey partitionKey,
TargetReplicaSelector targetReplicaSelector,
string listenerName,
OperationRetrySettings retrySettings,
CancellationToken cancellationToken)
{
var client = await _innerClientFactory.GetClientAsync(
serviceUri,
partitionKey,
targetReplicaSelector,
listenerName,
retrySettings,
cancellationToken);
return new AuditedFabricTransportServiceRemotingClient(client);
}
public async Task<IServiceRemotingClient> GetClientAsync(
ResolvedServicePartition previousRsp,
TargetReplicaSelector targetReplicaSelector,
string listenerName,
OperationRetrySettings retrySettings,
CancellationToken cancellationToken)
{
var client = await _innerClientFactory.GetClientAsync(
previousRsp,
targetReplicaSelector,
listenerName,
retrySettings,
cancellationToken);
return new AuditedFabricTransportServiceRemotingClient(client);
}
public Task<OperationRetryControl> ReportOperationExceptionAsync(
IServiceRemotingClient client,
ExceptionInformation exceptionInformation,
OperationRetrySettings retrySettings,
CancellationToken cancellationToken)
{
return _innerClientFactory.ReportOperationExceptionAsync(
client,
exceptionInformation,
retrySettings,
cancellationToken);
}
public event EventHandler<CommunicationClientEventArgs<IServiceRemotingClient>> ClientConnected;
public event EventHandler<CommunicationClientEventArgs<IServiceRemotingClient>> ClientDisconnected;
}
This implementation simply passes along anything heavy lifting to the underlying factory, while returning it's own auditable client that similarily encapsulates a IServiceRemotingClient:
public class AuditedFabricTransportServiceRemotingClient : IServiceRemotingClient, ICommunicationClient
{
private readonly IServiceRemotingClient _innerClient;
public AuditedFabricTransportServiceRemotingClient(IServiceRemotingClient innerClient)
{
_innerClient = innerClient;
}
~AuditedFabricTransportServiceRemotingClient()
{
if (this._innerClient == null) return;
var disposable = this._innerClient as IDisposable;
disposable?.Dispose();
}
Task<byte[]> IServiceRemotingClient.RequestResponseAsync(ServiceRemotingMessageHeaders messageHeaders, byte[] requestBody)
{
messageHeaders.SetUser(ServiceRequestContext.Current.User);
messageHeaders.SetCorrelationId(ServiceRequestContext.Current.CorrelationId);
return this._innerClient.RequestResponseAsync(messageHeaders, requestBody);
}
void IServiceRemotingClient.SendOneWay(ServiceRemotingMessageHeaders messageHeaders, byte[] requestBody)
{
messageHeaders.SetUser(ServiceRequestContext.Current.User);
messageHeaders.SetCorrelationId(ServiceRequestContext.Current.CorrelationId);
this._innerClient.SendOneWay(messageHeaders, requestBody);
}
public ResolvedServicePartition ResolvedServicePartition
{
get { return this._innerClient.ResolvedServicePartition; }
set { this._innerClient.ResolvedServicePartition = value; }
}
public string ListenerName
{
get { return this._innerClient.ListenerName; }
set { this._innerClient.ListenerName = value; }
}
public ResolvedServiceEndpoint Endpoint
{
get { return this._innerClient.Endpoint; }
set { this._innerClient.Endpoint = value; }
}
}
Now, in here is where we actually (and finally) set the audit name that we want to pass along to the service.
Call chains and service request context
One final piece of the puzzle, the ServiceRequestContext, which is a custom class that allows us to handle an ambient context for a service request call. This is relevant because it gives us an easy way to propagate that context information, like the user or a correlation id (or any other header information we want to pass between client and service), in a chain of calls. The implementation ServiceRequestContext looks like:
public sealed class ServiceRequestContext
{
private static readonly string ContextKey = Guid.NewGuid().ToString();
public ServiceRequestContext(Guid correlationId, string user)
{
this.CorrelationId = correlationId;
this.User = user;
}
public Guid CorrelationId { get; private set; }
public string User { get; private set; }
public static ServiceRequestContext Current
{
get { return (ServiceRequestContext)CallContext.LogicalGetData(ContextKey); }
internal set
{
if (value == null)
{
CallContext.FreeNamedDataSlot(ContextKey);
}
else
{
CallContext.LogicalSetData(ContextKey, value);
}
}
}
public static Task RunInRequestContext(Func<Task> action, Guid correlationId, string user)
{
Task<Task> task = null;
task = new Task<Task>(async () =>
{
Debug.Assert(ServiceRequestContext.Current == null);
ServiceRequestContext.Current = new ServiceRequestContext(correlationId, user);
try
{
await action();
}
finally
{
ServiceRequestContext.Current = null;
}
});
task.Start();
return task.Unwrap();
}
public static Task<TResult> RunInRequestContext<TResult>(Func<Task<TResult>> action, Guid correlationId, string user)
{
Task<Task<TResult>> task = null;
task = new Task<Task<TResult>>(async () =>
{
Debug.Assert(ServiceRequestContext.Current == null);
ServiceRequestContext.Current = new ServiceRequestContext(correlationId, user);
try
{
return await action();
}
finally
{
ServiceRequestContext.Current = null;
}
});
task.Start();
return task.Unwrap<TResult>();
}
}
This last part was much influenced by the SO answer by Stephen Cleary. It gives us an easy way to handle the ambient information down a hierarcy of calls, weather they are synchronous or asyncronous over Tasks. Now, with this we have a way of setting that information also in the Dispatcher on the service side:
public override Task<byte[]> RequestResponseAsync(
IServiceRemotingRequestContext requestContext,
ServiceRemotingMessageHeaders messageHeaders,
byte[] requestBody)
{
var user = messageHeaders.GetUser();
var correlationId = messageHeaders.GetCorrelationId();
return ServiceRequestContext.RunInRequestContext(async () =>
await base.RequestResponseAsync(
requestContext,
messageHeaders,
requestBody),
correlationId, user);
}
(GetUser() and GetCorrelationId() are just helper methods that gets and unpacks the headers set by the client)
Having this in place means that any new client created by the service for any aditional call will also have the sam headers set, so in the scenario ServiceA -> ServiceB -> ServiceC we will still have the same user set in the call from ServiceB to ServiceC.
what? that easy? yes ;)
From inside a service, for instance a Stateless OWIN web api, where you first capture the user information, you create an instance of ServiceProxyFactoryand wrap that call in a ServiceRequestContext:
var task = ServiceRequestContext.RunInRequestContext(async () =>
{
var serviceA = ServiceProxyFactory.CreateServiceProxy<IServiceA>(new Uri($"{FabricRuntime.GetActivationContext().ApplicationName}/ServiceA"));
await serviceA.DoStuffAsync(CancellationToken.None);
}, Guid.NewGuid(), user);
Ok, so to sum it up - you can hook into the service remoting to set your own headers. As we see above there is some work that needs to be done to get a mechanism for that in place, mainly creating your own subclasses of the underlying infrastructure. The upside is that once you have this in place, then you have a very easy way for auditing your service calls.
I would like to see if/how it would be possible to plug into the deserialization process for a parameter that's decorated with the ServiceBusTrigger?
Say I have a function that looks like:
public static void HandleMessage([ServiceBusTrigger("myqueue")] MyCustomType myCustomType) { }
How would I go about taking over the deserialization? I know that there is a notion of an IArgumentBindingProvider and IArgumentBinding but it does not look like ServiceBusTrigger supports these concepts.
I know I can use GetBody<Stream>() and deserialize that way but I'd like to know if I can plug into the ServiceBusTrigger's pipeline. By the looks at the SDK, the ServiceBusTrigger has a hard coded list of IQueueArgumentBindingProviders and so I can't add my own.
If you have a look at the Azure WebJobs SDK Extensions, there is an overview on how to create your own bindings :
Binding Extensions Overview
Otherwise the ServiceBusConfiguration exposes a MessagingProvider property that allows you to intercept the ServiceBusTrigger pipeline:
private static void Main()
{
var sbConfig = new ServiceBusConfiguration()
{
MessagingProvider = // you implemetation of the MessagingProvider class goes here !!!
};
var config = new JobHostConfiguration();
config.UseServiceBus(sbConfig);
new JobHost(config).RunAndBlock();
}
Here is a simple skeleton of a MessagingProvider implementation:
public sealed class MyMessagingProvider : MessagingProvider
{
private readonly ServiceBusConfiguration _config;
public MyMessagingProvider(ServiceBusConfiguration config)
: base(config)
{
_config = config;
}
public override MessageProcessor CreateMessageProcessor(string entityPath)
{
return new MyMessageProcessor(_config.MessageOptions);
}
private class MyMessageProcessor : MessageProcessor
{
public MyMessageProcessor(OnMessageOptions messageOptions)
: base(messageOptions)
{
}
public override Task<bool> BeginProcessingMessageAsync(BrokeredMessage message, CancellationToken cancellationToken)
{
// Intercept the message before the execution of the triggerred function
return base.BeginProcessingMessageAsync(message, cancellationToken);
}
public override Task CompleteProcessingMessageAsync(BrokeredMessage message, FunctionResult result, CancellationToken cancellationToken)
{
// Intercept the message after the execution of the triggerred function and before being completed
return base.CompleteProcessingMessageAsync(message, result, cancellationToken);
}
}
}
So you're main function now looks like that:
private static void Main()
{
var sbConfig = new ServiceBusConfiguration();
sbConfig.MessagingProvider = new MyMessagingProvider(sbConfig);
var config = new JobHostConfiguration();
config.UseServiceBus(sbConfig);
new JobHost(config).RunAndBlock();
}
I structured my project into multiple mobile services, grouped by the application type eg:
my-core.azure-mobile.net (user, device)
my-app-A.azure-mobile.net (sales, order, invoice)
my-app-B.azure-mobile.net (inventory & parts)
I'm using custom authentication for all my services, and I implemented my own SSO by setting the same master key to all 3 services.
Things went well when I tested using REST client, eg. user who "logged in" via custom api at my-core.azure-mobile.net is able to use the returned JWT token to access restricted API of the other mobile services.
However, in my xamarin project, only the first (note, in sequence of creation) MobileServiceClient object is working properly (eg. returning results from given table). The client object are created using their own url and key respectively, and stored in a dictionary.
If i created client object for app-A then only create for app-B, I will be able to perform CRUD+Sync on sales/order/invoice entity, while CRUD+Sync operation on inventory/part entity will just hang there. The situation is inverse if I swap the client object creation order.
I wonder if there is any internal static variables used within the MobileServiceClient which caused such behavior, or it is a valid bug ?
=== code snippet ===
public class AzureService
{
IDictionary<String, MobileServiceClient> services = new Dictionary<String, MobileServiceClient>();
public MobileServiceClient Init (String key, String applicationURL, String applicationKey)
{
return services[key] = new MobileServiceClient (applicationURL, applicationKey);
}
public MobileServiceClient Get(String key)
{
return services [key];
}
public void InitSyncContext(MobileServiceSQLiteStore offlineStore)
{
// Uses the default conflict handler, which fails on conflict
// To use a different conflict handler, pass a parameter to InitializeAsync.
// For more details, see http://go.microsoft.com/fwlink/?LinkId=521416
var syncHandler = new MobileServiceSyncHandler ();
foreach(var client in services) {
client.Value.SyncContext.InitializeAsync (offlineStore, syncHandler);
}
}
public void SetAuthenticationToken(String uid, String token)
{
var user = new MobileServiceUser(uid);
foreach(var client in services) {
client.Value.CurrentUser = user;
client.Value.CurrentUser.MobileServiceAuthenticationToken = token;
}
}
public void ClearAuthenticationToken()
{
foreach(var client in services) {
client.Value.CurrentUser = null;
}
}
}
=== more code ===
public class DatabaseService
{
public static MobileServiceSQLiteStore LocalStore = null;
public static string Path { get; set; }
public static ISet<IEntityMappingProvider> Providers = new HashSet<IEntityMappingProvider> ();
public static void Init (String dbPath)
{
LocalStore = new MobileServiceSQLiteStore(dbPath);
foreach(var provider in Providers) {
var types = provider.GetSupportedTypes ();
foreach(var t in types) {
JObject item = null;
// omitted detail to create JObject using reflection on given type
LocalStore.DefineTable(tableName, item);
}
}
}
}
=== still code ===
public class AzureDataSyncService<T> : IAzureDataSyncService<T>
{
public MobileServiceClient ServiceClient { get; set; }
public virtual Task<List<T>> GetAll()
{
try
{
var theTable = ServiceClient.GetSyncTable<T>();
return theTable.ToListAsync();
}
catch (MobileServiceInvalidOperationException msioe)
{
Debug.WriteLine("GetAll<{0}> EXCEPTION TYPE: {1}, EXCEPTION:{2}", typeof(T).ToString(), msioe.GetType().ToString(), msioe.ToString());
}
catch (Exception e)
{
Debug.WriteLine("GetAll<{0}> EXCEPTION TYPE: {1}, EXCEPTION:{2}", typeof(T).ToString(), e.GetType().ToString(), e.ToString());
}
List<T> theCollection = Enumerable.Empty<T>().ToList();
return Task.FromResult(theCollection);
}
}
=== code ===
public class UserService : AzureDataSyncService<User>
{
}
public class PartService : AzureDataSyncService<Part>
{
}
const string coreApiURL = #"https://my-core.azure-mobile.net/";
const string coreApiKey = #"XXXXX";
const string invApiURL = #"https://my-inventory.azure-mobile.net/";
const string invApiKey = #"YYYYY";
public async void Foo ()
{
DatabaseService.Providers.Add (new CoreDataMapper());
DatabaseService.Providers.Add (new InvDataMapper ());
DatabaseService.Init (DatabaseService.Path);
var coreSvc = AzureService.Instance.Init ("Core", coreApiURL, coreApiKey);
var invSvc = AzureService.Instance.Init ("Inv", invApiURL, invApiKey);
AzureService.Instance.InitSyncContext (DatabaseService.LocalStore);
AzureService.Instance.SetAuthenticationToken("AAA", "BBB");
UserService.Instance.ServiceClient = coreSvc;
PartService.Instance.ServiceClient = invSvc;
var x = await UserService.GetAll(); // this will work
var y = await PartService.GetAll(); // but not this
}
It's ok to use multiple MobileServiceClient objects, but not with the same local database. The offline sync feature uses a particular system tables to keep track of table operations and errors, and it is not supported to use the same local store across multiple sync contexts.
I'm not totally sure why it is hanging in your test, but it's possible that there is a lock on the local database file and the other sync context is waiting to get access.
You should instead use different local database files for each service and doing push and pull on each sync context. With your particular example, you just need to move LocalStore out of DatabaseService and into a dictionary in AzureService.
In general, it seems like an unusual design to use multiple services from the same client app. Is there a particular reason that the services need to be separated from each other?
I've got this action in MVC
[OutputCache(Duration = 1200, VaryByParam = "*")]
public ActionResult FilterArea( string listType, List<int> designersID, int currPage = 1 )
{
// Code removed
}
that fails to present the correct HTML with url like
http://example.com/en-US/women/clothing?designersID=158
http://example.com/en-US/women/clothing?designersID=158&designersID=13
Is this a know bug of OutputCache in .NET cause cannot recognize VaryByParam with a list param or am I missing something?
I too had the same issue in MVC3 and I believe it's still the same case in MVC5.
Here is the setup I had.
Request
POST, Content-Type:application/json, passing in an array of string as the parameter
{ "options": ["option1", "option2"] }
Controller Method
[OutputCache(Duration = 3600, Location = OutputCacheLocation.Any, VaryByParam = "options")]
public ActionResult GetOptionValues(List<string> options)
I tried every option possible with OutputCache and it just wasn't caching for me. Binding worked fine for the actual method to work. My biggest suspicion was that OutputCache wasn't creating unique cache keys so I even pulled its code out of System.Web.MVC.OutputCache to verify. I've verified that it properly builds unique keys even when a List<string> is passed in. Something else is buggy in there but wasn't worth spending more effort.
OutputCacheAttribute.GetUniqueIdFromActionParameters(filterContext,
OutputCacheAttribute.SplitVaryByParam(this.VaryByParam);
Workaround
I ended up creating my own OutputCache attribute following another SO post. Much easier to use and I can go enjoy the rest of the day.
Controller Method
[MyOutputCache(Duration=3600)]
public ActionResult GetOptionValues(Options options)
Custom Request class
I've inherited from List<string> so I can call the overriden .ToString() method in MyOutputcache class to give me a unique cache key string. This approach alone has resolved similar issues for others but not for me.
[DataContract(Name = "Options", Namespace = "")]
public class Options: List<string>
{
public override string ToString()
{
var optionsString= new StringBuilder();
foreach (var option in this)
{
optionsString.Append(option);
}
return optionsString.ToString();
}
}
Custom OutputCache class
public class MyOutputCache : ActionFilterAttribute
{
private string _cachedKey;
public int Duration { get; set; }
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
if (filterContext.HttpContext.Request.Url != null)
{
var path = filterContext.HttpContext.Request.Url.PathAndQuery;
var attributeNames = filterContext.ActionParameters["Options"] as AttributeNames;
if (attributeNames != null) _cachedKey = "MYOUTPUTCACHE:" + path + attributeNames;
}
if (filterContext.HttpContext.Cache[_cachedKey] != null)
{
filterContext.Result = (ActionResult) filterContext.HttpContext.Cache[_cachedKey];
}
else
{
base.OnActionExecuting(filterContext);
}
}
public override void OnActionExecuted(ActionExecutedContext filterContext)
{
filterContext.HttpContext.Cache.Add(_cachedKey, filterContext.Result, null,
DateTime.Now.AddSeconds(Duration), System.Web.Caching.Cache.NoSlidingExpiration,
System.Web.Caching.CacheItemPriority.Default, null);
base.OnActionExecuted(filterContext);
}
}
I am using this code to try and render a razor partial view as a string for the purposes of sending an email.
public static string RenderPartialToString(
string userControlPath,
object viewModel,
ControllerContext controllerContext,
TempDataDictionary tempData)
{
using (var writer = new StringWriter())
{
var viewDataDictionary = new ViewDataDictionary(viewModel);
var view = new WebFormView(controllerContext, userControlPath);
var viewContext = new ViewContext(
controllerContext,
view,
viewDataDictionary,
tempData,
writer
);
viewContext.View.Render(viewContext, writer);
return writer.GetStringBuilder().ToString();
}
}
The problem is that I get the follow error:
must derive from ViewPage, ViewPage<TModel>, ViewUserControl, or ViewUserControl<TModel>. Stack Trace: at System.Web.Mvc.WebFormView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) at .... RenderPartialToString
How would I fix that ?
Indeed, WebFormView doesn't inherit from the mentioned classes, just IView. I did a little Google research and got a prototype working. This page was the most helpful.
I created an empty MVC3 application and created the following HomeController. When I run the application, the page shows the rendered string. The resultAsString variable shows how to capture the rendering as a string.
using System;
using System.IO;
using System.Web.Mvc;
public class HomeController : Controller
{
public ActionResult Index()
{
var result = RenderPartial(this.ControllerContext, "This is #DateTime.Now right now");
var resultAsString = result.Content;
return result;
}
private ContentResult RenderPartial(ControllerContext controllerContext, string template)
{
var temporaryViewPath = string.Format("~/Views/{0}.cshtml", Guid.NewGuid());
using (var stringWriter = new StringWriter())
{
using (var fileStream = System.IO.File.Create(Server.MapPath(temporaryViewPath)))
{
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine(template);
streamWriter.Close();
}
fileStream.Close();
}
var razor = new RazorView(controllerContext, temporaryViewPath, null, false, null);
razor.Render(new ViewContext(controllerContext, razor, new ViewDataDictionary(), new TempDataDictionary(), stringWriter), stringWriter);
System.IO.File.Delete(Server.MapPath(temporaryViewPath));
return Content(stringWriter.ToString());
}
}
}