如何以纯字符串形式获取视图文件内容

Question

ASP.NET Core 5 MVC 应用程序使用来自 https://github.com/adoconnection/RazorEngineCore 的 razor 引擎在运行时将视图呈现为字符串。

如何以字符串形式获取视图

~/Views/Checkout/Order.cshtml

内容？

我试过了

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

但它会抛出错误。应用程序可以部署为单个文件或单独的文件。

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

如何以字符串形式获取视图 ~/Views/Checkout/Order.cshtml 内容？

您可以尝试使用以下代码创建 ViewRenderService：

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);
    }
}

在上述服务中添加以下引用：

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;

然后，在Startup.ConfigureServices方法中注册ViewRenderService：

services.AddScoped<IViewRenderService, ViewRenderService>();

之后，您可以使用此服务将视图页面呈现为字符串：

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();
    }

结果是这样的：

Answer 2

在您的评论回复中您写道：

如何强制视图包含为程序集资源？它仅由应用程序用作要呈现的字符串内容。它不是常规视图，不用于创建 html 页面。将构建操作设置为嵌入式资源是否足够。应该使用哪个路径来获取该资源？

您可以自己推断资源流名称，或者您可以通过直接编辑.csproj

文件来手动指定名称

来指定

<LogicalName>

（我不知道为什么这个元素没有在属性窗口，确实应该如此）。后一个选项更好，因为移动文件时名称将保持不变）。