How to convert ASP.Net MVC 5 ExecuteResult to ASP.Net Core ExecuteResultAsync

Question

I'm migrating one of my Asp.Net MVC 5 project to Asp.Net Core. I have a custom ActionResult, which renders the view as partial view if the request was ajax request, and renders the view as normal view with layout if the request was a normal request. I have issues with converting the old ExecuteResult to new ExecuteResultAsync.

Here it is my old code:

public override void ExecuteResult(ControllerContext context)
    {
        context.HttpContext.Response.Buffer = true;
        context.Controller.ViewData.Model = Model;

        using (var sw = new StringWriter())
        {
            var request = context.RequestContext.HttpContext.Request;

            if (string.IsNullOrEmpty(ViewName))
            {
                ViewName = request.RequestContext.RouteData.GetRequiredString("action");
            }

            var viewResult = request.IsAjaxRequest()
                ? ViewEngines.Engines.FindPartialView(context, ViewName)
                : ViewEngines.Engines.FindView(context, ViewName, "_Layout");

            var viewContext = new ViewContext(context, viewResult.View, context.Controller.ViewData, context.Controller.TempData, sw);
            viewResult.View.Render(viewContext, sw);
            context.HttpContext.Response.Write(sw.GetStringBuilder().ToString());
        }
    }

And here it is my half converted code:

public override async Task ExecuteResultAsync(ActionContext context)
    {
        context.HttpContext.Response.Buffer = true; //broken
        context.HttpContext.Controller.ViewData.Model = Model; //broken

        using (var sw = new StringWriter())
        {
            var request = context.HttpContext.Request;

            if (string.IsNullOrEmpty(ViewName))
                ViewName = context.ActionDescriptor.Name;

            var engine = context.HttpContext.RequestServices.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;

            var viewResult = request.Headers["X-Requested-With"] == "XMLHttpRequest"
                ? engine.FindPartialView(context, ViewName)
                : engine.FindView(context, ViewName);

            var viewContext = new ViewContext(context, viewResult.View, context.Controller.ViewData, context.Controller.TempData, sw, new HtmlHelperOptions()); //broken
            await viewResult.View.RenderAsync(viewContext);
            await context.HttpContext.Response.WriteAsync(sw.GetStringBuilder().ToString());
        }
    }

My main issue is the ControllerContext -> ActionContext migrating. Please help me to convert ControllerContext to ActionContext. Thank you very much!

N. Taylor Mullen · Accepted Answer · 2016-04-26 22:12:15Z

1

Ehh, put something together to fit RC2 bits real quick. Feel free to improve on it:

public override async Task ExecuteResultAsync(ActionContext context)
{
    var request = context.HttpContext.Request;

    if (string.IsNullOrEmpty(ViewName))
    {
        ViewName = context.ActionDescriptor.Name;
    }

    var engine = context.HttpContext.RequestServices.GetService(typeof(ICompositeViewEngine)) as ICompositeViewEngine;

    var viewResult = engine.FindView(context, ViewName, isMainPage: request.Headers["X-Requested-With"] != "XMLHttpRequest");
    var tempDataProvider = context.HttpContext.RequestServices.GetService(typeof(ITempDataProvider)) as ITempDataProvider;
    var modelMetaDataProvider = context.HttpContext.RequestServices.GetService(typeof(IModelMetadataProvider)) as IModelMetadataProvider;

    using (var writer = new HttpResponseStreamWriter(context.HttpContext.Response.Body, Encoding.UTF8))
    {
        var tempData = new TempDataDictionary(context.HttpContext, tempDataProvider);
        var viewData = new ViewDataDictionary(modelMetaDataProvider, context.ModelState)
        {
            Model = Model
        };
        var viewContext = new ViewContext(
            context,
            viewResult.View,
            viewData,
            tempData,
            writer,
            new HtmlHelperOptions());

        await viewResult.View.RenderAsync(viewContext);
    }
}

answered Apr 26, 2016 at 22:12

N. Taylor Mullen

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5 Comments

martonx Over a year ago

Thank you, I will check it!

martonx Over a year ago

This line has this error: var tempData = new TempDataDictionary(context.HttpContext, tempDataProvider); //Argument 1: cannot convert from 'Microsoft.AspNet.Http.HttpContext' to 'Microsoft.AspNet.Http.IHttpContextAccessor'

martonx Over a year ago

This should be the correct line: var tempData = new TempDataDictionary(new HttpContextAccessor { HttpContext = context.HttpContext }, tempDataProvider);

N. Taylor Mullen Over a year ago

Note, my bits are for RC2 :)

Jenan Over a year ago

It would be nice to rewrite this sample to new version. :)

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