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How do I resolve HttpContext from a RegisterEvent to retrieve a View in a string in asp.net core 3and Electron.net?

I've tried Dependency injection, but that always gives me a HttpContextAccessor.Current or ActionContext as null because I'm not in a request state (I think). So how can I get this context to just take a view, transform it to a html string (with Model if necessary) and throw it back in JS ? I even tried to call directly the Controller action, but it always gives HttpContext as null... I'm using Asp.NET Core 3.
Please, if someone has been going through, help me :-)
Thanks,
Edit:
I have an asp.net core based on Electron.net for a desktop application. I use a lot of IPC communication to retrieve data from backend c# using Electron.IpcMain.On. I register an action as listener in c# in a class. The main problem is that this class is really outside a normal HttpRequest or a Controller. Here is some sample code:
IpcBase Class
public abstract class IpcBase: IBaseIpcCommunicationClass
{
/// <summary>
/// Find a way to get rid of this and take more than the first window
/// </summary>
protected static BrowserWindow _mainWindow = Electron.WindowManager.BrowserWindows.First();
/// <summary>
/// Send an ipcEvent with a parameter class
/// </summary>
/// <param name="parameters">Parameters to fill</param>
public void RegisterIpcEvent<T>(IpcRegisterModel<T> registerModel) => Electron.IpcMain.On(registerModel.key, o => registerModel.action((T)
((JObject)o).ToObject(typeof(T))));
/// <summary>
/// Send a reply inside a registerevent
/// </summary>
/// <typeparam name="T">Type of model</typeparam>
/// <param name="model">model</param>
public void SendReply<T>(IpcSendParamsModel<T> model)
{
if (!string.IsNullOrEmpty(model.replyTo))
{
Electron.IpcMain.Send(_mainWindow, model.replyTo, model);
}
}
...
}
IpcUI (to get the controller view, just like an ajax call on a controller that retrieve the view in String (I already have that, but not with Ipc)
public class IpcUI: IpcBase
{
public IpcUI(IRazorViewToStringService razorViewRenderService)
{
Console.WriteLine("IpcUI::Constructor");
RegisterIpcEvent(new IpcRegisterModel<IpcSendParamsModel<AjaxPartialModel>>("renderPartial", async (param) =>
{
var param = new IpcSendParamsModel<AjaxPartialModel>("RenderPartial")
{
key = "renderPartial",
model = new AjaxPartialModel()
{
DataModel = "{items: [{\r\n MaterialIcon: \"\",\r\n Title: \"Games\",\r\n Selectable: true,\r\n Active: true,\r\n Key: \"GAMES\",\r\n BadgeCaption: \"new\",\r\n BadgeValue: \"123\",\r\n BadgeColor: \"red darken-1\",\r\n BadgePartialLink: \"\",\r\n BadgeContainerLink: \"\",\r\n BadgeModelLink: \"\",\r\n PartialLink: \"Home/Index\",\r\n ContainerLink: \"#body-content\",\r\n ModelLink: \"\"\r\n }] }".JsonDeserialize<MenuModelHeader>(),
PartialName = "PartialViews/_TopMenu"
}
};
try
{
param.results =
await razorViewRenderService.CreateAndResolveInstanceFromGeneric().RenderViewToStringAsync($"~/Views/{param.model.PartialName}.cshtml",
param.model.DataModel);
}
catch (Exception e)
{
IpcClasses.ExceptionManager.SendException(this, e, $"IpcUI params: {param.model.JsonSerialize()}");
}
}));
}
}
Razor Service (Mostly taken from here Generate string from view)
Added in startup:
services.AddHttpContextAccessor();
services.AddSingleton<IActionContextAccessor, ActionContextAccessor>();
services.AddScoped<IRazorViewToStringService, RazorRazorViewToStringService>();
When I create an instance of IpcUI, DI gives me the service, but without any HttpContext or ActionContext... Sorry for the lack of information from my last edit :-). Hope it is a bit more specific.
Oh ! I forgot something, IpcUI is created at runtime not with a new (because that don't work) but with a custom extension function that retrieves the IServiceProvider for DI:
In startup
ExtensionsUtils.ServiceProvider = app.ApplicationServices;
In ExtensionsUtils
/// <summary>
/// This is called in configure services to get the collection of services in an extension static class
/// </summary>
public static IServiceProvider ServiceProvider { get; set; }
/// <summary>
/// Create a reference from type T with DI
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="o"></param>
/// <returns></returns>
public static T CreateAndResolveInstanceFromGeneric<T>(this T o)
{
return (T)ActivatorUtilities.CreateInstance<T>(ServiceProvider);
}
Edit 2:
I have tried to access IRazorViewToStringService from a real controller constructor and it's null again... What Am I doing wrong ???
private readonly IRazorViewToStringService _razorViewRenderService;
public BaseController(IRazorViewToStringService razorViewRenderService)
{
_razorViewRenderService = razorViewRenderService;
}
...
/// <summary>
/// Return a success http code and a View rendered as string
/// </summary>
/// <param name="ViewName">Name of MVC View (or PartialView)</param>
/// <param name="Model">Model to pass if any</param>
/// <returns>JSON: { result: "type", description: "Html Code" }</returns>
public async Task<ActionResult> CheckAndReturnView(string ViewName, object Model = null)
{
return Ok(await _razorViewRenderService.RenderViewToStringAsync(ViewName, Model));
}

Web api Controller having constructors with parameters as Generic Service Interface

In my Web api project I am having a controller DocumentViewerV1Controller which has a code as:
/// <summary>
///
/// </summary>
/// <param name="documentViewerService"></param>
public DocumentViewerV1Controller(IDocumentViewerService<HtmlViewInformation> documentViewerService)
{
_documentViewerHtmlService = documentViewerService;
}
/// <summary>
///
/// </summary>
/// <param name="documentViewerService"></param>
public DocumentViewerV1Controller(IDocumentViewerService<PageImage> documentViewerService)
{
_documentViewerImageService = documentViewerService;
}/// <summary>
/// Rendering Document as Html
/// </summary>
/// <returns></returns>
[HttpGet]
[Route(WebApiConfig.RootApiUri + "/v1/viewashtml/{docid}")]
public string ViewAsHtml(string docId)
{
var documentInfo = new DocumentInfo { DocumentName = HostingEnvironment.MapPath("~/Uploads/") + docId };
var response = _documentViewerHtmlService.RenderDocument(documentInfo, DocumentRenderType.Html);
return GenerateResponse(response);
}
When I run my service, make a call and debug the constructor initialization, It doesn't goes through the initialization which makes _documentViewerHtmlService as null, eventually fails returning Null reference Exception.
Is it possible to have service Interface as IDocumentViewerService?

Yes, but you'll need to remove one of the constructors or tell it which one to use.
container.RegisterType<IViewerInformation, HtmlViewerInformation>();
container.RegisterType<IDocumentViewerService<IViewerInformation>, DocumentViewerServce<IViewerInformation>>();
You may / may not also need to initialize some of the constructors which you can do by
container.RegisterType<IDocumentViewerService<IViewerInformation>, DocumentViewerServce<IViewerInformation>>(
new InjectionConstructor(...));

Serving static files without going through OWIN

Short:
For each and every request a new OWIN context is created, I would like to be able to prevent this for certain resource types or paths (images, css, js).
Full:
In our application start-up we register a dbcontext creation delegate so that the dbcontext will be created just once per request.
public virtual void Configuration(IAppBuilder app)
{
app.CreatePerOwinContext(Factory.DbContextCreateDelegate);
}
If a client makes a request for the style sheet, an OWIN context will be created an thus a new dbcontext will also be created. I would like to be able to either not create the OwinContext at all, or at least to be able to prevent some of it's "on create" callbacks to be executed for certain request types/paths.
Alternatively, as I can see why the approach of (partially) "disabling" OWIN would lead to problems, I would like to hear what the best practice would be? How can I serve a static file without creating a database context for each request? (small remark here is that our static files are embedded resources served using a virtual path provider... The problem also occurs for "normal" static files.)
Background: Yesterday I started noticing that every now and then some parts of our application did not load. Sometimes it was single image, sometimes the entire CSS file. After some investigation I saw that some requests were throwing http 500 errors, the exception thrown was often things like a SQL connection time out (but also other exceptions).
While we are of course trying to fix those exceptions. I do believe it to be complete nonsense for our application to set up a database connection when a client makes a request for a single image... That's about 10 database connections for a single page request???
Seems to me like such an obvious problem but I have been Googling all of yesterday and found nothing close to a solution or work around. What am I missing stack?
EDIT: I just tried an approach where I did not actually create the dbcontext but a stub instead. In hindsight this obviously is not the solution to this problem as the OwinContext tries to continue it's process and will critically fail when it tries to get the user from the database using that stub dbcontext. The dbcontext is not the problem, I need to completely bypass Owin... I think...

Microsoft.Owin.StaticFiles to the rescue!
I would still like to know why this is not enabled by default in the MVC OWIN template application. But for most cases it is just a matter of a single line of code to enable static files in OWIN.
BASIC SCENARIO
Setting up Owin to treat a folder and its contents as static files:
public virtual void Configuration(IAppBuilder app)
{
app.UseStaticFiles("/PathToYourStaticFilesFolder");
}
SCENARIO WITH EMBEDDED RESOURCES
Unfortunately for me we are serving most of our static content as embedded resources using an implementation of a VirtualPathProvider. Luckily this is also relatively easy to implement, though it does require writing a wrapper around your VirtualPathProvider to implement the required IFileSystem and IFileInfo interfaces that OWIN requires.
Relevant parts of code from my final solution, not posting the entire VirtualPathProvider as there are plenty of examples for that online.
The wrapper around the VirtualPathProvider:
/// <summary>
/// Represents a virtual file system.
/// A wrapper around <see cref="MyCustomVirtualPathProvider"/> implementing
/// IFileSystem for use in Owin StaticFiles.
/// </summary>
public class VirtualFileSystem : IFileSystem
{
/// <summary>
/// Locate the path in the virtual path provider
/// </summary>
/// <param name="subpath">The path that identifies the file</param>
/// <param name="fileInfo">The discovered file if any</param>
/// <returns>
/// True if a file was located at the given path
/// </returns>
public bool TryGetFileInfo(string subpath, out IFileInfo fileInfo)
{
MyCustomVirtualPathProvider virtualPathProvider =
(MyCustomVirtualPathProvider) HostingEnvironment.VirtualPathProvider;
if (!virtualPathProvider.FileExists(subpath))
{
fileInfo = null;
return false;
}
try
{
EmbeddedResourceVirtualFile virtualFile =
(EmbeddedResourceVirtualFile) virtualPathProvider.GetFile(subpath);
fileInfo = new EmbeddedResourceFileInfo(virtualFile);
return true;
}
catch (InvalidCastException)
{
fileInfo = null;
return false;
}
}
/// <summary>
/// Not used in our implementation
/// </summary>
/// <param name="subpath"></param>
/// <param name="contents"></param>
/// <returns></returns>
public bool TryGetDirectoryContents(string subpath, out IEnumerable<IFileInfo> contents)
{
throw new NotImplementedException();
}
}
The wrapper around the embedded resource:
/// <summary>
/// Represents the file info of an embedded resource
/// </summary>
public class EmbeddedResourceFileInfo : IFileInfo
{
/// <summary>
/// Return file contents as readonly stream. Caller should dispose stream when complete.
/// </summary>
/// <returns>
/// The file stream
/// </returns>
public Stream CreateReadStream()
{
return virtualFile.Open();
}
/// <summary>
/// The length of the file in bytes, or -1 for a directory info
/// </summary>
public long Length => virtualFile.Length;
/// <summary>
/// The name of the file
/// </summary>
public string Name => virtualFile.Name;
/// <summary>
/// When the file was last modified
/// </summary>
public DateTime LastModified => virtualFile.LastModified;
/// <summary>
/// Returns null as these are virtual files
/// </summary>
public string PhysicalPath => null;
/// <summary>
/// True for the case TryGetDirectoryContents has enumerated a sub-directory
/// </summary>
public bool IsDirectory => virtualFile.IsDirectory;
private readonly EmbeddedResourceVirtualFile virtualFile;
/// <summary>
/// Construct using a <see cref="EmbeddedResourceVirtualFile"/>
/// </summary>
/// <param name="virtualFile"></param>
public EmbeddedResourceFileInfo(EmbeddedResourceVirtualFile virtualFile)
{
this.virtualFile = virtualFile;
}
}
And lastly, setting up Owin to use our virtual file system:
public virtual void Configuration(IAppBuilder app)
{
var staticFilesOptions = new StaticFileOptions
{
FileSystem = new VirtualFileSystem()
};
app.UseStaticFiles(staticFilesOptions);
}

Dynamic .NET WebAPI 5.2 Controllers based on some an abstract base type

Assuming that the REST and Data access interactions will be somewhat standard, I want to be able to create an abstract type to represent entity objects to pass back and forth from REST client (e.g. JavaScript in a browser) to the persistence layer without writing/registering/routing a bunch of different WebAPI controllers.
How can one create one controller base type implementation to manage persistence of several different entity type REST interactions? I.e. how can I make this work with WebAPI?
using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;
using System.Web;
using System.Web.Http;
namespace DynamicEntityApiControllers
{
/// <summary>
///
/// </summary>
public class EntityController<T> : ApiController
where T : EntityObject
{
private readonly IDaoProvider daoProvider;
/// <summary>
/// Initializes a new instance of the <see cref="EntityController{T}"/> class.
/// </summary>
/// <param name="daoProvider">The DAO provider.</param>
protected EntityController(IDaoProvider daoProvider)
{
this.daoProvider = daoProvider;
}
/// <summary>
/// Gets the name of the collection.
/// </summary>
/// <value>
/// The name of the collection.
/// </value>
protected string CollectionName
{
get
{
return (string)this.RequestContext.RouteData.Values["controller"];
}
}
/// <summary>
/// Gets the specified entity by key from the collection.
/// </summary>
/// <param name="key">The key.</param>
/// <returns></returns>
public T Get(string key)
{
return this.daoProvider.Output<T>(this.CollectionName, key).Data;
}
/// <summary>
/// Creates or updates the specified entity by key in the collection.
/// </summary>
/// <param name="key">The key.</param>
/// <param name="updating">The updating.</param>
/// <returns></returns>
public T Put(string key, [FromBody] T updating)
{
var daoObject = DaoEntity.Create(this.CollectionName, key, updating);
return this.daoProvider.Input<T>(daoObject).Data;
}
/// <summary>
/// Creates or Updates the collection specified entirely.
/// </summary>
/// <param name="replacingCollection">The replacing collection.</param>
/// <returns></returns>
public IEnumerable<T> Put([FromBody] IEnumerable<T> replacingCollection)
{
return this.daoProvider.Input<T>(replacingCollection
.Select(o => DaoEntity.Create(this.CollectionName, o)));
}
/// <summary>
/// creates a new entity in the specified collection.
/// </summary>
/// <param name="creating">The creating.</param>
/// <returns></returns>
public T Post([FromBody] T creating)
{
var daoEntity = DaoEntity.Create(this.CollectionName, creating);
return this.daoProvider.Input(daoEntity).Data;
}
/// <summary>
/// Deletes the specified entity by key from the collection.
/// </summary>
/// <param name="key">The key.</param>
public void Delete(string key)
{
this.daoProvider.Delete(this.CollectionName, key);
}
}
}
the JavaScript client must look/act something like this:
$.ajax({url: '/Book', method: 'POST', data: {title: 'This StackOverflow Post', pageCount: '124' })
.done(function(data) {
$.get('/Book/'+data.Key).done(function(data) {
// this will return the book you just created
console.dir(data);
})
})
$.ajax({url: '/Book', method: 'POST', data: {title: 'Some other StackOverflow Post', pageCount: '236' })
.done(function(data) {
$.get('/Magazine/'+data.Key).done(function(data) {
// this will return 404 status code because you're asking for the book's key
// in the Magazines collection
console.dir(data);
})
})

the sample solution has a bunch TODO here (like actually do right with ETag header, if-match, etc...) but I had to do about 4 queries across StackOverflow to find these bits.
Prerequisites:
Autofac (IoC) integration with WebAPI
WebAPI Controller Location / DependencyResolver (these are not the same things)
C# Generics
Reflection IL Emitting
very minimal REST understanding and what an ETag is.
GIT source folder
briefly, here is the logic:
create a base type (entityobject)
identify all those entities at IoC Registration time via reflection (Implementer is responsible for specifying which assemblies to scan)
create concrete implementations of abstract class EntityController via IL Emitting
Tell the SupportsDynamicControllerTypeResolver about these dynamic types
IDaoProvider implementation is the "persistence" layer. implement your persistence logic here.. in this sample, an in memory dictionary is used.
And what happens when a request is made:
- RouteTable is interrogated (finds {controller}/{key} route which is an HttpRoute
- Controller name matches EntityObject implementer name minus Entity. I.e. BookEntity => BookController
- SupportsDynamicControllerTypeResolver is required here to get dynamic assembly types as valid candidates for WebApi to try to activate.
- HTTP Put/Get/Post/Delete methods find the correct method
- persistence layer does the rest

Nunit Testing MVC Site

I've run into a bit of an issue trying to unit test an MVC site I have: I require a lot of the ASP.NET environment to be running (generation of httpcontexts, sessions, cookies, memberships, etc.) to fully test everything.
Even to test some of the less front end stuff needs memberships in order to properly work, and it's been finicky to get this all spoofed by hand.
Is there a way to spin up an application pool inside of NUnit tests? That seems like the easiest way.

If written properly, you shouldn't need to have a real context, real session, cookies, etc. The MVC framework by default provides a HttpContext that can be mocked/stubbed. I'd recommend using a mocking framework like Moq or Rhino Mocks and creating a MockHttpContext class that creates a mock context with all of the properties that you need to test against set up. Here's a mock HttpContext that uses Moq
/// <summary>
/// Mocks an entire HttpContext for use in unit tests
/// </summary>
public class MockHttpContextBase
{
/// <summary>
/// Initializes a new instance of the <see cref="MockHttpContextBase"/> class.
/// </summary>
public MockHttpContextBase() : this(new Mock<Controller>().Object, "~/")
{
}
/// <summary>
/// Initializes a new instance of the <see cref="MockHttpContextBase"/> class.
/// </summary>
/// <param name="controller">The controller.</param>
public MockHttpContextBase(Controller controller) : this(controller, "~/")
{
}
/// <summary>
/// Initializes a new instance of the <see cref="MockHttpContextBase"/> class.
/// </summary>
/// <param name="url">The URL.</param>
public MockHttpContextBase(string url) : this(new Mock<Controller>().Object, url)
{
}
/// <summary>
/// Initializes a new instance of the <see cref="MockHttpContextBase"/> class.
/// </summary>
/// <param name="controller">The controller.</param>
/// <param name="url">The URL.</param>
public MockHttpContextBase(ControllerBase controller, string url)
{
HttpContext = new Mock<HttpContextBase>();
Request = new Mock<HttpRequestBase>();
Response = new Mock<HttpResponseBase>();
Output = new StringBuilder();
HttpContext.Setup(x => x.Request).Returns(Request.Object);
HttpContext.Setup(x => x.Response).Returns(Response.Object);
HttpContext.Setup(x => x.Session).Returns(new FakeSessionState());
Request.Setup(x => x.Cookies).Returns(new HttpCookieCollection());
Request.Setup(x => x.QueryString).Returns(new NameValueCollection());
Request.Setup(x => x.Form).Returns(new NameValueCollection());
Request.Setup(x => x.ApplicationPath).Returns("~/");
Request.Setup(x => x.AppRelativeCurrentExecutionFilePath).Returns(url);
Request.Setup(x => x.PathInfo).Returns(string.Empty);
Response.Setup(x => x.Cookies).Returns(new HttpCookieCollection());
Response.Setup(x => x.ApplyAppPathModifier(It.IsAny<string>())).Returns((string path) => path);
Response.Setup(x => x.Write(It.IsAny<string>())).Callback<string>(s => Output.Append(s));
var requestContext = new RequestContext(HttpContext.Object, new RouteData());
controller.ControllerContext = new ControllerContext(requestContext, controller);
}
/// <summary>
/// Gets the HTTP context.
/// </summary>
/// <value>The HTTP context.</value>
public Mock<HttpContextBase> HttpContext { get; private set; }
/// <summary>
/// Gets the request.
/// </summary>
/// <value>The request.</value>
public Mock<HttpRequestBase> Request { get; private set; }
/// <summary>
/// Gets the response.
/// </summary>
/// <value>The response.</value>
public Mock<HttpResponseBase> Response { get; private set; }
/// <summary>
/// Gets the output.
/// </summary>
/// <value>The output.</value>
public StringBuilder Output { get; private set; }
}
/// <summary>
/// Provides Fake Session for use in unit tests
/// </summary>
public class FakeSessionState : HttpSessionStateBase
{
/// <summary>
/// backing field for the items in session
/// </summary>
private readonly Dictionary<string, object> _items = new Dictionary<string, object>();
/// <summary>
/// Gets or sets the <see cref="System.Object"/> with the specified name.
/// </summary>
/// <param name="name">the key</param>
/// <returns>the value in session</returns>
public override object this[string name]
{
get
{
return _items.ContainsKey(name) ? _items[name] : null;
}
set
{
_items[name] = value;
}
}
}
There's a few things that you could add further like a HTTP Headers collection, but hopefully it demonstrates what you can do.
To use
var controllerToTest = new HomeController();
var context = new MockHttpContextBase(controllerToTest);
// do stuff that you want to test e.g. something goes into session
Assert.IsTrue(context.HttpContext.Session.Count > 0);
With regards to Membership providers or other providers, you've hit on something that can be hard to test. I would abstract the usage of the provider behind an interface such that you can provide a fake for the interface when testing a component that relies on it. You'll still have trouble unit testing the concrete implementation of the interface that uses the provider however but your mileage may vary as to how far you want/have to go with regards to unit testing and code coverage.

I'm not aware of a way to do that since your code isn't in that process and requires a host that isn't in aspnet either. (I've been wrong before though haha)
Theres an older HttpSimulator from Phil Haack, have you given that a whirl?
http://haacked.com/archive/2007/06/19/unit-tests-web-code-without-a-web-server-using-httpsimulator.aspx

You need to build wrapper interfaces for those services. The original MVC2 and MV3 starter project templates did this by default, but for some reason they dropped that in the latest versions.
You can try to find samples of the original AccountController code to give you a starting place. They used IMembershipService and IFormsAuthenticationService
It's relatively straightforward to mock session, context, etc..

Take a look at the MVCContrib project (http://mvccontrib.codeplex.com/) as they have a helper for creating controllers that have all the various contextual objects populated (like HttpContext).