将 Razor 页面渲染为字符串 [英] Render a Razor Page to string
问题描述
我需要将 Razor 页面呈现为字符串的一部分.
I need to render a Razor Page partial to a string.
我想创建一个控制器操作，该操作以包含部分视图和其他可选参数的 JSON 进行响应.
I want to create a controller action that responds with JSON containing a partial view and other optional parameters.
我熟悉以下将视图呈现为字符串的示例:https://github.com/aspnet/Entropy/blob/dev/samples/Mvc.RenderViewToString/RazorViewToStringRenderer.cs
I am familiar with the following example that renders a View to a string: https://github.com/aspnet/Entropy/blob/dev/samples/Mvc.RenderViewToString/RazorViewToStringRenderer.cs
然而，它与 Pages 不兼容，因为它只在 Views 目录中搜索，所以即使我给它一个绝对路径到部分它也会尝试定位我的 _Layout.cshtml(它甚至不应该这样做！) 并且找不到它.
However, it is not compatible with Pages, as it only searches in the Views directory, so even if I give it an absolute path to the partial it tries to locate my _Layout.cshtml (which it shouldn't even do!) and fails to find it.
我已经尝试修改它以呈现页面，但是当我尝试呈现它时，我最终在我的部分中为 ViewData 获得了 NullReferenceException.我怀疑它与 NullView 有关，但我不知道该放什么(RazorView 的构造函数需要许多我不知道如何正确获取的对象).
I have tried to modify it so it renders pages, but I end up getting a NullReferenceException for ViewData in my partial when attempting to render it. I suspect it has to do with NullView, but I have no idea what to put there instead (the constructor for RazorView requires many objects that I don't know how to get correctly).
代码:
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0: https://www.apache.org/licenses/LICENSE-2.0
// Modified by OronDF343: Uses pages instead of views.
using System;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
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.ViewFeatures;
using Microsoft.AspNetCore.Mvc.ViewFeatures.Internal;
using Microsoft.AspNetCore.Routing;
namespace TestAspNetCore.Services
{
public class RazorPageToStringRenderer
{
private readonly IRazorViewEngine _viewEngine;
private readonly ITempDataProvider _tempDataProvider;
private readonly IServiceProvider _serviceProvider;
public RazorPageToStringRenderer(
IRazorViewEngine viewEngine,
ITempDataProvider tempDataProvider,
IServiceProvider serviceProvider)
{
_viewEngine = viewEngine;
_tempDataProvider = tempDataProvider;
_serviceProvider = serviceProvider;
}
public async Task<string> RenderPageToStringAsync<TModel>(string viewName, TModel model)
{
var actionContext = GetActionContext();
var page = FindPage(actionContext, viewName);
using (var output = new StringWriter())
{
var viewContext = new ViewContext(actionContext,
new NullView(),
new ViewDataDictionary<TModel>(new EmptyModelMetadataProvider(),
new ModelStateDictionary())
{
Model = model
},
new TempDataDictionary(actionContext.HttpContext,
_tempDataProvider),
output,
new HtmlHelperOptions());
page.ViewContext = viewContext;
await page.ExecuteAsync();
return output.ToString();
}
}
private IRazorPage FindPage(ActionContext actionContext, string pageName)
{
var getPageResult = _viewEngine.GetPage(executingFilePath: null, pagePath: pageName);
if (getPageResult.Page != null)
{
return getPageResult.Page;
}
var findPageResult = _viewEngine.FindPage(actionContext, pageName);
if (findPageResult.Page != null)
{
return findPageResult.Page;
}
var searchedLocations = getPageResult.SearchedLocations.Concat(findPageResult.SearchedLocations);
var errorMessage = string.Join(
Environment.NewLine,
new[] { $"Unable to find page '{pageName}'. The following locations were searched:" }.Concat(searchedLocations));
throw new InvalidOperationException(errorMessage);
}
private ActionContext GetActionContext()
{
var httpContext = new DefaultHttpContext { RequestServices = _serviceProvider };
return new ActionContext(httpContext, new RouteData(), new ActionDescriptor());
}
}
}
推荐答案
我就是这样做的.
一如既往地在 Startup.cs 中注册服务
As always register the Service in Startup.cs
services.AddScoped<IViewRenderService, ViewRenderService>();
服务定义如下:
public interface IViewRenderService
{
Task<string> RenderToStringAsync<T>(string viewName, T model) where T : PageModel;
}
public class ViewRenderService : IViewRenderService
{
private readonly IRazorViewEngine _razorViewEngine;
private readonly ITempDataProvider _tempDataProvider;
private readonly IServiceProvider _serviceProvider;
private readonly IHttpContextAccessor _httpContext;
private readonly IActionContextAccessor _actionContext;
private readonly IRazorPageActivator _activator;
public ViewRenderService(IRazorViewEngine razorViewEngine,
ITempDataProvider tempDataProvider,
IServiceProvider serviceProvider,
IHttpContextAccessor httpContext,
IRazorPageActivator activator,
IActionContextAccessor actionContext)
{
_razorViewEngine = razorViewEngine;
_tempDataProvider = tempDataProvider;
_serviceProvider = serviceProvider;
_httpContext = httpContext;
_actionContext = actionContext;
_activator = activator;
}
public async Task<string> RenderToStringAsync<T>(string pageName, T model) where T : PageModel
{
var actionContext =
new ActionContext(
_httpContext.HttpContext,
_httpContext.HttpContext.GetRouteData(),
_actionContext.ActionContext.ActionDescriptor
);
using (var sw = new StringWriter())
{
var result = _razorViewEngine.FindPage(actionContext, pageName);
if (result.Page == null)
{
throw new ArgumentNullException($"The page {pageName} cannot be found.");
}
var view = new RazorView(_razorViewEngine,
_activator,
new List<IRazorPage>(),
result.Page,
HtmlEncoder.Default,
new DiagnosticListener("ViewRenderService"));
var viewContext = new ViewContext(
actionContext,
view,
new ViewDataDictionary<T>(new EmptyModelMetadataProvider(), new ModelStateDictionary())
{
Model = model
},
new TempDataDictionary(
_httpContext.HttpContext,
_tempDataProvider
),
sw,
new HtmlHelperOptions()
);
var page = ((Page)result.Page);
page.PageContext = new Microsoft.AspNetCore.Mvc.RazorPages.PageContext
{
ViewData = viewContext.ViewData
};
page.ViewContext = viewContext;
_activator.Activate(page, viewContext);
await page.ExecuteAsync();
return sw.ToString();
}
}
}
我是这样称呼的
emailView.Body = await this._viewRenderService.RenderToStringAsync("Email/ConfirmAccount", new Email.ConfirmAccountModel
{
EmailView = emailView,
});
Email/ConfirmAccount"是我的 Razor 页面(Under pages)的路径.ConfirmAccountModel"是该页面的页面模型.
"Email/ConfirmAccount" is the path to my Razor page (Under pages). "ConfirmAccountModel" is my page model for that page.
ViewData为null，因为Page的ViewData是在设置PageContext的时候设置的，所以如果没有设置ViewData为null.
ViewData is null because the ViewData for the Page is set when the PageContext is set, so if this is not set ViewData is null.
我还发现我不得不打电话
I also found that I had to call
_activator.Activate(page, viewContext);
为了一切顺利.这尚未经过全面测试，因此可能不适用于所有场景，但应该可以帮助您入门.
For it all to work. This is not fully tested yet so may not work for all scenarios but should help you get started.
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