How to get view file content as plain string

Question

ASP.NET Core 5 MVC application uses razor engine from https://github.com/adoconnection/RazorEngineCore to render views as strings at runtime.

How to get view ~/Views/Checkout/Order.cshtml content as string?

I tried

ReadTemplate("~/Views/Checkout/Order.cshtml")

but it throws an error. Application may deployed as single file or as separate files.

string ReadTemplate(string filename)
{
    var stream = GetType().Assembly.GetManifestResourceStream(filename);

    if (stream == null)
        throw new ApplicationException(filename + " view not found");

    StreamReader reader = new(stream);
    string template = reader.ReadToEnd();
    reader.Close();
    return template;
}

Answer 1

How to get view ~/Views/Checkout/Order.cshtml content as string?

You could try to create a ViewRenderService with the following code:

public interface IViewRenderService
{
    Task<string> RenderToString(string viewName, object model);
}
public class ViewRenderService : IViewRenderService
{
    private readonly IRazorViewEngine _razorViewEngine;
    private readonly ITempDataProvider _tempDataProvider;
    private readonly IHttpContextAccessor _contextAccessor;

    public ViewRenderService(IRazorViewEngine razorViewEngine,
                             ITempDataProvider tempDataProvider,
                             IHttpContextAccessor contextAccessor)
    {
        _razorViewEngine = razorViewEngine;
        _tempDataProvider = tempDataProvider;
        _contextAccessor = contextAccessor;
    }

    public async Task<string> RenderToString(string viewName, object model)
    {
        var actionContext = new ActionContext(_contextAccessor.HttpContext, _contextAccessor.HttpContext.GetRouteData(), new ActionDescriptor());

        await using var sw = new StringWriter();
        var viewResult = FindView(actionContext, viewName);

        if (viewResult == null)
        {
            throw new ArgumentNullException($"{viewName} does not match any available view");
        }

        var viewDictionary = new ViewDataDictionary(new EmptyModelMetadataProvider(), new ModelStateDictionary())
        {
            Model = model
        };

        var viewContext = new ViewContext(
            actionContext,
            viewResult,
            viewDictionary,
            new TempDataDictionary(actionContext.HttpContext, _tempDataProvider),
            sw,
            new HtmlHelperOptions()
        );

        await viewResult.RenderAsync(viewContext);
        return sw.ToString();
    }

    private IView FindView(ActionContext actionContext, string viewName)
    {
        var getViewResult = _razorViewEngine.GetView(executingFilePath: null, viewPath: viewName, isMainPage: true);
        if (getViewResult.Success)
        {
            return getViewResult.View;
        }

        var findViewResult = _razorViewEngine.FindView(actionContext, viewName, isMainPage: true);
        if (findViewResult.Success)
        {
            return findViewResult.View;
        }

        var searchedLocations = getViewResult.SearchedLocations.Concat(findViewResult.SearchedLocations);
        var errorMessage = string.Join(
            Environment.NewLine,
            new[] { $"Unable to find view '{viewName}'. The following locations were searched:" }.Concat(searchedLocations));

        throw new InvalidOperationException(errorMessage);
    }
}

Add the following references in the above service:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Abstractions;
using Microsoft.AspNetCore.Mvc.ModelBinding;
using Microsoft.AspNetCore.Mvc.Razor;
using Microsoft.AspNetCore.Mvc.Rendering;
using Microsoft.AspNetCore.Mvc.ViewEngines;
using Microsoft.AspNetCore.Mvc.ViewFeatures;
using Microsoft.AspNetCore.Routing;

Then, register the ViewRenderService in the Startup.ConfigureServices method:

services.AddScoped<IViewRenderService, ViewRenderService>();

After that, you could use this service to render view page as a string:

public class HomeController : Controller
{ 
    private readonly IViewRenderService _viewRenderService;
    public HomeController(IViewRenderService viewRenderService)
    {  
        _viewRenderService = viewRenderService;
    }
     
    public async Task<IActionResult> CategoryIndex()
    {  
       //The model will be transferred to the View page.
        var stulist = new List<Student>() { new Student() { StudentName = "AA" }, new Student() { StudentName = "BB" } };

        var result =  _viewRenderService.RenderToString("Views/Student/Index.cshtml", stulist).Result;

        return View();
    }

The result like this: