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Sequence contains no matching element error when returning class Type of Interface using IsAssignableFrom

This is a follow up question to another post I created around implementing a UI test solution that could toggle which classes to execute code from based on interfaces. The whole goal was to re use test code on versions of apps that are identical (Web vs WPF).
The code compiles fine, but after the test is ran it bombs out on the GetPageModelType method call. Below is my implementation pretty much identical to the linked post, with a few minor adjustments to abstract some of the page object creation on a TestClassBase
UI Test that can determine which classes to execute code from at runtime using interfaces
Interface and corresponding Page Object classes
public interface ILogin
{
void Login(string username, string password);
}
public class WebLogin : ILogin
{
private readonly IWebDriver driver;
public WebLogin(IWebDriver driver)
{
this.driver = driver;
}
public void Login(string username, string password)
{
Console.WriteLine("Web Success!");
}
}
public class WPFLogin : ILogin
{
private readonly WindowsDriver<WindowsElement> session;
public WPFLogin(WindowsDriver<WindowsElement> session)
{
this.session = session;
}
public void Login(string username, string password)
{
Console.WriteLine("WPF Success!");
}
}
Page Object factory classes
public interface IPageModelFactory
{
ILogin CreateLogin();
}
public class WebPageModelFactory : IPageModelFactory
{
private readonly IWebDriver driver;
public WebPageModelFactory(IWebDriver driver)
{
this.driver = driver;
}
public ILogin CreateLogin()
{
return new WebLogin(driver);
}
}
public class WPFPageModelFactory : IPageModelFactory
{
private readonly WindowsDriver<WindowsElement> session;
public WPFPageModelFactory(WindowsDriver<WindowsElement> session)
{
this.session = session;
}
public ILogin CreateLogin()
{
return new WPFLogin(session);
}
}
public class PageModelFactory
{
private readonly object client;
public PageModelFactory(object client)
{
this.client = client;
}
// Create Page Objects
public ILogin CreateLoginPage()
{
var pageModelType = GetPageModelType<ILogin>();
var constructor = pageModelType.GetConstructor(new Type[] { client.GetType() });
return (ILogin)constructor.Invoke(new object[] { client });
}
private Type GetPageModelType<TPageModelInterface>()
{
return client.GetType().Assembly.GetTypes().Single(type => type.IsClass && typeof(TPageModelInterface).IsAssignableFrom(type));
}
}
TestClassBase - base class for tests, simplifies test scripts
[TestFixture]
public class TestClassBase
{
// WinAppDriver variables
private static string WinAppDriverExe = "C:\\Program Files (x86)\\Windows Application Driver\\WinAppDriver.exe";
private string WindowsApplicationDriverUrl = "http://127.0.0.1:4723";
// Sessions
public WindowsDriver<WindowsElement> session;
public IWebDriver driver;
// Declare Page Objects
public ILogin login = null;
[SetUp]
public void SetUp()
{
if (GlobalData.targetHost.Equals("WPF"))
{
// Capabilities
AppiumOptions appCapabilities = new AppiumOptions();
appCapabilities.AddAdditionalCapability("app", GetExeFile());
appCapabilities.AddAdditionalCapability("appWorkingDir", GetWorkingDirectory());
// Create Session
session = new WindowsDriver<WindowsElement>(new Uri(WindowsApplicationDriverUrl), appCapabilities, TimeSpan.FromMinutes(3));
session.Manage().Window.Maximize();
// Pass session to page objects
PageModelFactory wpfPages = new PageModelFactory(session);
login = wpfPages.CreateLoginPage();
} else if (GlobalData.targetHost.Equals("Web"))
{
}
}
[TearDown]
public void TearDown()
{
// Clean up code...
}
}
LoginTests
public class LoginTests : TestClassBase
{
[Test]
public void Login()
{
// Login
login.Login("", "");
}
}
Whats not pictured above is my GlobalData.cs class which just contains a bunch of hardcoded variables that are used in the tests. I have the targetHost variable set to "WPF" while testing this against the WPF host. The StartUp code does launch the app as expected, it fails when we call GetPageModelType on PageModelFactory.CreateLoginPage();

I wasn't able to see this in my answer on your original question. The assembly in which the "client" resides and the assembly in which the page models reside are different. That means the PageModelFactory will need a second constructor parameter to know which assembly to search when initializing new page models:
public class PageModelFactory
{
private readonly object client;
private Assembly Assembly => GetType().Assembly;
public PageModelFactory(object client)
{
this.client = client;
}
// Create Page Objects
public ILogin CreateLoginPage()
{
var pageModelTypes = GetPageModelTypes<ILogin>();
var constructorSignature = new Type[] { client.GetType() };
foreach (var type in pageModelTypes)
{
var constructor = type.GetConstructor(constructorSignature);
if (constructor != null)
return (ILogin)constructor.Invoke(new object[] { client });
}
throw new InvalidOperationException($"No class found implementing ILogin with a constructor that accepts {client.GetType().FullName} as an argument in assembly {Assembly.Name}");
}
private IEnumerable<Type> GetPageModelTypes<TPageModelInterface>()
{
return Assembly.GetTypes()
.Where(type => type.IsClass
&& typeof(TPageModelInterface).IsAssignableFrom(type));
}
}

MVC MEF Error: Make sure that the controller has a parameterless public constructor

For MVC app using MEF, sometimes I get the erorr ""
I have a .NET solution with
One MVC Web application project and,
Many class libraries projects which take care of authentication, getting configurations, making external API calls etc.
I have configured the MEF as shown below through the code and deployed this on Web Server using IIS. Observed the below error couple of times, after which I tried to load the page multiple times but it still throws the same error.
Once I refreshed the application pool, then only the error disappears. I had been trying hard to debug and understand the error, but with no success. Am I misconfiguring MEF anywhere?
Global.asax:
public class Global : HttpApplication
{
void Application_Start(object sender, EventArgs e)
{
AreaRegistration.RegisterAllAreas();
GlobalConfiguration.Configure(WebApiConfig.Register);
RouteConfig.RegisterRoutes(RouteTable.Routes);
var pluginFolders = LoadMefComponents();
Bootstrapper.Compose(pluginFolders);
IControllerFactory mefControllerFactory = new MefControllerFactory(Bootstrapper.Container);
ControllerBuilder.Current.SetControllerFactory(mefControllerFactory);
}
protected List<string> LoadMefComponents()
{
var pluginFolders = new List<string>();
string ModulesPath = CommonUtility.GetApplicationDirectory();
var plugins = Directory.GetDirectories(ModulesPath).ToList();
plugins.ForEach(path =>
{
var directoryInfo = new DirectoryInfo(path);
pluginFolders.Add(directoryInfo.Name);
});
return pluginFolders;
}
}
MEFControllerFactory.cs: This file resides in App_Start
public class MefControllerFactory : DefaultControllerFactory
{
private readonly CompositionContainer _container;
private readonly Dictionary<IController, Lazy<object, object>> exports;
private readonly object syncRoot;
public MefControllerFactory(CompositionContainer container)
{
if (container == null)
{
throw new ArgumentNullException("container");
}
this._container = container;
this.exports = new Dictionary<IController, Lazy<object, object>>();
this.syncRoot = new object();
}
protected override IController GetControllerInstance(System.Web.Routing.RequestContext requestContext, Type controllerType)
{
Lazy<object, object> export = _container.GetExports(controllerType, null, null).FirstOrDefault();
var controller = null == export ? base.GetControllerInstance(requestContext, controllerType)
: (IController)export.Value;
lock (this.syncRoot)
{
this.exports.Add(controller, export);
}
return controller;
}
public override void ReleaseController(IController controller)
{
lock (this.syncRoot)
{
var export = this.exports[controller];
this.exports.Remove(controller);
// this._container.ReleaseExport(export);
}
((IDisposable)controller).Dispose();
}
}
Bootstrapper.cs: This file resides in App_Start
public class Bootstrapper
{
private static CompositionContainer compositionContainer;
private static bool IsLoaded = false;
public static CompositionContainer Container
{
get { return compositionContainer; }
set { compositionContainer = value; }
}
public static void Compose(List<string> pluginFolders)
{
if (IsLoaded) return;
var catalog = new AggregateCatalog();
catalog.Catalogs.Add(new AssemblyCatalog(Assembly.GetExecutingAssembly()));
catalog.Catalogs.Add(new DirectoryCatalog(CommonUtility.GetApplicationDirectory()));
compositionContainer = new CompositionContainer(catalog);
compositionContainer.ComposeParts();
IsLoaded = true;
}
public static T GetInstance<T>(string contractName = null)
{
var type = default(T);
if (compositionContainer == null) return type;
if (!string.IsNullOrWhiteSpace(contractName))
type = compositionContainer.GetExportedValue<T>(contractName);
else
type = compositionContainer.GetExportedValue<T>();
return type;
}
}
CommonUtility.cs: This file resides in App_Start
public class CommonUtility
{
public static string GetApplicationDirectory()
{
string codeBase = Assembly.GetExecutingAssembly().CodeBase;
UriBuilder uri = new UriBuilder(codeBase);
string path = Uri.UnescapeDataString(uri.Path);
return Path.GetDirectoryName(path);
}
}
HomeController.cs:
[CommonExceptionFilter]
public class HomeController : Controller
{
private IConfigurationManager _configurationManager;
[ImportingConstructor]
public HomeController()
{
_configurationManager = Bootstrapper.GetInstance<IConfigurationManager>();
}
public async Task<ActionResult> Index()
{
//Business Logic
return View()
}
}
IConfigurationManager.cs
[InheritedExport]
public interface IConfigurationManager
{
string GetConfigurationValue(string keyName)
}
ConfigurationManager.cs
[PartCreationPolicy(CreationPolicy.Shared)]
public class ConfigurationManager: IConfigurationManager
{
[ImportingConstructor]
public ConfigurationManager()
{
}
public string GetConfigurationValue(string keyName)
{
return "";
}
}
IHttpHandlers Used In The MVC Project:
public class CommonServiceHandler : HttpTaskAsyncHandler, IRequiresSessionState
{
private ICommonServiceHandlerManager _commonServiceHandlerManager;
public CommonServiceHandler()
{
_commonServiceHandlerManager = Bootstrapper.GetInstance<ICommonServiceHandlerManager>();
}
public override bool IsReusable
{
get
{
return false;
}
}
}

This error indicates that at least one controller exists that its constructor parameters are not resolved.
Every controller needs a constructor to be resolved at run-time. By default every c# class has a default (parameter-less) constructor that can be called when an instance of the class is needed to be created.
However, after defining an explicit constructor, you lose the default constructor, therefore, you need to make sure that all your controllers have either a parameter-less constructor or if instead they have a parametric constructor the parameters need to be registered through dependency injection.

How to store data in cache?

I created a ViewComponent to display a List<Product>, the list is valorized taken data from a REST API service, this is my class implementation:
public class ProductsViewComponent : ViewComponent
{
private readonly HttpClient _client;
public ProductsViewComponent(HttpClient client)
{
_client = client ?? throw new ArgumentNullException(nameof(client));
}
public async Task<IViewComponentResult> InvokeAsync(string date)
{
using (var response = await _client.GetAsync($"/"product/get_products/{date}"))
{
response.EnsureSuccessStatusCode();
var products = await response.Content.ReadAsAsync<List<Product>>();
return View(products);
}
}
}
I load the List inside an html table which is available inside the Components folder: Views\Shared\Components\Products\Default.cshtml.
In each View that needs to display the Products I did:
#await Component.InvokeAsync("Products", new { date = myDate })
The REST API is called using the HttpClient configured in the Startup.cs as following:
services.AddHttpClient<ProductsViewComponent>(c =>
{
c.BaseAddress = new Uri('https://api.myservice.com');
});
This works well, but the main problem is each time the user reload the page or maybe go inside another View which require to display the list of products, then the app will make another API call.
Is possible store the list in something like a cache and prevent to call the API again if the date is equal than the previous date selected?
I'm learning ASP.NET Core so I'm not really expert on this argument.
Thanks in advance for any help.

As per microsoft documentation https://learn.microsoft.com/en-us/aspnet/core/performance/caching/memory?view=aspnetcore-2.1
you can use IMemoryCache to cache data
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddMemoryCache();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
public void Configure(IApplicationBuilder app)
{
app.UseMvcWithDefaultRoute();
}
}
and create instance of IMemoryCache. This is an example from Microsoft documentation. You can Create another class to handle this all together and In below example this is just saving DateTime But, you can save any object in cache and when you try to read that value from cache just need to cast that object into a Type.
I will strongly recommend you go through the above documentation.
public class HomeController : Controller
{
private IMemoryCache _cache;
public HomeController(IMemoryCache memoryCache)
{
_cache = memoryCache;
}
public IActionResult CacheTryGetValueSet()
{
DateTime cacheEntry;
// Look for cache key.
if (!_cache.TryGetValue(CacheKeys.Entry, out cacheEntry))
{
// Key not in cache, so get data.
cacheEntry = DateTime.Now;
// Set cache options.
var cacheEntryOptions = new MemoryCacheEntryOptions()
// Keep in cache for this time, reset time if accessed.
.SetSlidingExpiration(TimeSpan.FromSeconds(3));
// Save data in cache.
_cache.Set(CacheKeys.Entry, cacheEntry, cacheEntryOptions);
}
return View("Cache", cacheEntry);
}
}
Update: CacheKeys.Entry is a static class where all keys are defined. (Just coding standards). Please check the above documentation link.
public static class CacheKeys
{
public static string Entry { get { return "_Entry"; } }
public static string CallbackEntry { get { return "_Callback"; } }
public static string CallbackMessage { get { return "_CallbackMessage"; } }
public static string Parent { get { return "_Parent"; } }
public static string Child { get { return "_Child"; } }
public static string DependentMessage { get { return "_DependentMessage";} }
public static string DependentCTS { get { return "_DependentCTS"; } }
public static string Ticks { get { return "_Ticks"; } }
public static string CancelMsg { get { return "_CancelMsg"; } }
public static string CancelTokenSource { get { return "_CancelTokenSource";} }
}

You can use a distributed cache and so use Redis for example with a ConnectionMultiplexer.
And so foreach call you can call your redis for the cache which is implement thanks to an interface call here 'IDistributedCache'
You can find a lot of documentation to implement cache and use it.
: .Net framework
DotNet Core
Your controller X :
[HttpGet]
[Route("{itemId}")]
public async Task<IHttpActionResult> GetItemById(int eventId, [FromUri]EventTabs tabId)
{
ServiceResponse<ItemDto> result = await _itemDispatcher.GetItemById(itemId);
return WrapResponse(result);
}
Your dispatcher to get the item by id which use redis cache (already implement)
public class ItemDispatcher : ItemDispatcher
{
private readonly IUnitOfWork _unitOfWork;
private readonly IDistributedCache _distributedCache; // use interface of your implementation of redis cache
private readonly int _cacheDuration;
private readonly bool _isCacheEnabled;
public EventDispatcher(IUnitOfWork unitOfWork, IDistributedCache distCache)
{
_unitOfWork = unitOfWork;
_distributedCache = distCache; // init cache in constructor
_cacheDuration = _configuration.Get<int>("cache.duration"); // duration of your cache
_isCacheEnabled = _configuration.Get<bool>("cache.isEnable"); // if the cache is enable or not
}
public async Task<ServiceResponse<ItemDto>> GetItemById(int id)
{
// Add this for each Task call
var cacheKey = string.Empty;
if (_isCacheEnabled)
{
cacheKey = CacheUtils.GetCacheKey(CacheKeys.Item, id);
itemDto cacheResult = await _distributedCache.Get<ItemDto>(cacheKey);
if (cacheResult != null)
return new ServiceResponse<Item>(cacheResult);
}
}

Try This
Cache["KeyName"] = VariableOrTable; Cache.Insert("Key", VariableOrTable, null,
Cache.NoAbsoluteExpiration, ts);

Autofac property injection with MVC ValidationAttribute

I have found several questions on this subject, but have not found a clean and simple solution.
This is what I'm doing (using Autofac 3.3.0) for registering
builder.RegisterType<MerchantRepo>().As<IMerchantRepo>().PropertiesAutowired();
This is my validation class
public class MerchantMustBeUniqueAttribute : ValidationAttribute
{
public IMerchantRepo MerchantRepo { get; set; }
protected override ValidationResult IsValid(object value, ValidationContext validationContext)
{
int merchantId = Convert.ToInt32(value);
if (MerchantRepo.Exists(merchantId))
{
return new ValidationResult(ErrorMessage);
}
else
{
return ValidationResult.Success;
}
}
}
My merchant repo is always null.
Edit:
This is part of my view model
public class MerchantCreationModel
{
[Required]
[MerchantMustBeUnique(ErrorMessage = "Already exists!")]
public int? NewMerchantId { get; set; }
}
Autofac registration
public static void RegisterDependencies()
{
var builder = new ContainerBuilder();
builder.RegisterFilterProvider(); // Inject properties into filter attributes
builder.RegisterControllers(typeof(MvcApplication).Assembly);
builder.RegisterType<MerchantRepo>().As<IMerchantRepo>().PropertiesAutowired();
IContainer container = builder.Build();
DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
}

I solved my problem using the DependencyResolver class in ASP.NET MVC.
IMerchantRepo repo = DependencyResolver.Current.GetService<IMerchantRepo>();

I solved it in a way that doesn't end up littering the code with with Serice Location in this answer, enabling one to write:
class MyModel
{
...
[Required, StringLength(42)]
[ValidatorService(typeof(MyDiDependentValidator), ErrorMessage = "It's simply unacceptable")]
public string MyProperty { get; set; }
....
}
public class MyDiDependentValidator : Validator<MyModel>
{
readonly IUnitOfWork _iLoveWrappingStuff;
public MyDiDependentValidator(IUnitOfWork iLoveWrappingStuff)
{
_iLoveWrappingStuff = iLoveWrappingStuff;
}
protected override bool IsValid(MyModel instance, object value)
{
var attempted = (string)value;
return _iLoveWrappingStuff.SaysCanHazCheez(instance, attempted);
}
}
With some helper classes (look over there), you wire it up e.g. in ASP.NET MVC like so in the Global.asax :-
DataAnnotationsModelValidatorProvider.RegisterAdapterFactory(
typeof(ValidatorServiceAttribute),
(metadata, context, attribute) =>
new DataAnnotationsModelValidatorEx(metadata, context, attribute, true));

ASP.NET MVC Saving a view as HTML file

I have a pretty basic page that has a few images via relative paths that I need to save to a .html file.
I have used this in the past but had problems with the images.
public static class ActionResultExtensions
{
public static string Capture(this ActionResult result, ControllerContext controllerContext)
{
using (var capture = new ResponseCapture(controllerContext.RequestContext.HttpContext.Response))
{
result.ExecuteResult(controllerContext);
return capture.ToString();
}
}
}
public class ResponseCapture : IDisposable
{
private readonly HttpResponseBase _response;
private readonly TextWriter _originalWriter;
private StringWriter _localWriter;
public ResponseCapture(HttpResponseBase response)
{
_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) return;
_localWriter.Dispose();
_localWriter = null;
_response.Output = _originalWriter;
}
}
I'd like to know how to get the result WITH all of the CSS and images downloaded along with the HTML in a nice little package.

If you need it all in an HTML file you will need to do a tonne of nasties to inject css, js and images into the actual document, however you could use something like an MHT file which is a bundle of all resources required for a page.
this does the MHT thing by the looks, probably other options out there as well.
http://www.aspnetmht.com/Examples.aspx