CODEWITHSUNDEEP
asp.net-coreasp.net-core-mvc
eadam
eadam

Reputation: 26271

How to invoke View Component in a Asp.net Core Service Class?

I need to invoke a view component in a service class (not a controller). My aim to render the view component as a string and then process the HtmlString.

I can find help to render a view component in a controller where ActionContext is available but I cannot call my service from a controller. Any help please? I am happy to use Mock and default dependency injection.

Currently, I am using mvc 6 beta 2. Here is the code of my class

public class MyClass
{
    Microsoft.AspNet.Mvc.DefaultViewComponentHelper viewComponentHelper = null;
    Microsoft.AspNet.Mvc.Razor.RazorView razorView = null;

    public MyClass(IViewComponentSelector selector, IViewComponentInvokerFactory factory,
        IRazorPageFactory razorPageFactory, IRazorViewEngine razorViewEngine, IRazorPageActivator pageActivator,
        IViewStartProvider viewStartProvider)
    {
        viewComponentHelper = new DefaultViewComponentHelper(selector, factory);
        razorView = new RazorView(razorViewEngine, pageActivator, viewStartProvider, null, true);
    }

    public void MyAction
    {

        var view = new Mock<IView>().Object;    

        var actionContext = new ActionContext(new RouteContext(new DefaultHttpContext()), new ActionDescriptor());
        var viewData = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary());
        var viewContext = new ViewContext(actionContext, view, viewData, TextWriter.Null);

        viewComponentHelper.Contextualize(viewContext);
        var result = viewComponentHelper.Invoke("MyView").ToString();
    }
}

I am getting following exception

   at Microsoft.Framework.DependencyInjection.ServiceProviderExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.AspNet.Mvc.DefaultViewComponentActivator.<>c__DisplayClass6.<CreateActivateInfo>b__7(ViewContext viewContext)
   at Microsoft.AspNet.Mvc.PropertyActivator`1.Activate(Object view, TContext context)
   at Microsoft.AspNet.Mvc.DefaultViewComponentActivator.Activate(Object viewComponent, ViewContext context)
   at Microsoft.AspNet.Mvc.DefaultViewComponentInvoker.CreateComponent(ViewContext context)
   at Microsoft.AspNet.Mvc.DefaultViewComponentInvoker.InvokeSyncCore(MethodInfo method, ViewContext context)
   at Microsoft.AspNet.Mvc.DefaultViewComponentInvoker.Invoke(ViewComponentContext context)
   at Microsoft.AspNet.Mvc.DefaultViewComponentHelper.InvokeCore(TextWriter writer, Type componentType, Object[] arguments)
   at Microsoft.AspNet.Mvc.DefaultViewComponentHelper.Invoke(Type componentType, Object[] args)
   at Microsoft.AspNet.Mvc.DefaultViewComponentHelper.Invoke(String name, Object[] args)

Upvotes: 4

Views: 1520

Answers (1)

user2095880
user2095880

Reputation:

In the ConfigureServices section of your startup file, you need to register your service i.e.:

   public void ConfigureServices(IServiceCollection services)
   {
                // Add MVC services to the services container.
                //services.AddMvc();

                services.AddTransient...
    }

Upvotes: 1

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