想要ASP.NET Core中间件在MVC Razor View Engine后运行

Question

我想在MVC Razor View Engine处理完数据后在ASP.NET Core中运行MiddleWare模块。我可以让它运行，但它似乎没有收集所有的数据。我有一个标签助手来更新DI对象的集合，但是当中间件运行时，DI对象的集合是空的。我startup.cs看起来是这样的：

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) 
    { 
     loggerFactory.AddConsole(Configuration.GetSection("Logging")); 
     loggerFactory.AddDebug(); 

     if (env.IsDevelopment()) 
     { 
      app.UseDeveloperExceptionPage(); 
      app.UseBrowserLink(); 
     } 
     else 
     { 
      app.UseExceptionHandler("/Home/Error"); 
     } 

     app.UseStaticFiles(); 

     app.UseMiddleware<MyMiddleware>(); 

     app.UseMvc(routes => 
     { 
      routes.MapRoute(
       name: "default", 
       template: "{controller=Home}/{action=Index}/{id?}"); 
     }); 
    } 

和我的中间件是这样的：

public class MyMiddleware 
{ 
    private readonly RequestDelegate nextMiddleware; 
    private readonly IScriptManager _scriptManager; 

    public MyMiddleware(RequestDelegate next, IScriptManager scriptManager) 
    { 
     this.nextMiddleware = next; 
     _scriptManager = scriptManager; 
    } 

    public async Task Invoke(HttpContext context) 
    { 
     var cnt = _scriptManager.ScriptTexts.Count; 
     .. get HTML 
     Stream originalStream = context.Response.Body; 
     ... 
     .. update HTML 
     await context.Response.WriteAsync(htmlData); 

我得到我想要的HTML，但它似乎在我的DI采集没有更新。

***注 - 可能的，但不是工作结果筛选

 services.AddMvc(options => 
     { 
      options.Filters.Add(new AppendToHtmlBodyFilter()); 
     }); 

public class AppendToHtmlBodyFilter : TypeFilterAttribute 
{ 
    private readonly IScriptManager _scriptManager; 

    public AppendToHtmlBodyFilter():base(typeof(SampleActionFilterImpl)) 
    { 
    } 

    private class SampleActionFilterImpl : IResultFilter 
    { 
     private readonly IScriptManager _scriptManager; 

     public SampleActionFilterImpl(IScriptManager scriptManager) 
     { 
      _scriptManager = scriptManager; 
      //_logger = loggerFactory.CreateLogger<SampleActionFilterAttribute>(); 
     } 

     public void OnResultExecuted(ResultExecutedContext context) 
     { 
      var cnt = _scriptManager.ScriptTexts.Count; 
      Stream originalStream = context.HttpContext.Response.Body; 
      using (MemoryStream newStream = new MemoryStream()) 
      { 
       context.HttpContext.Response.Body = newStream; 
       context.HttpContext.Response.Body = originalStream; 
       newStream.Seek(0, SeekOrigin.Begin); 
       StreamReader reader = new StreamReader(newStream); 
       var htmlData = reader.ReadToEnd(); 

Answer 1

据我所知是没有办法在请求管道MVC后运行一个中间件。如果你想操纵剃刀输出，你可以使用过滤器。结果过滤器似乎适合您的情况。

结果过滤器非常适合任何需要直接环绕 视图执行或格式化程序执行的逻辑。结果过滤器可以替换或修改负责生成响应的操作结果。

参见官方文档https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters#result-filters

也看到如何使用依赖注入过滤https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters#dependency-injection

更新

我无法得到它的结果过滤器的工作（它的工作JSON结果，但没有工作viewresult）。

但是我发现中间件一个很好的例子：http://www.mikesdotnetting.com/article/269/asp-net-5-middleware-or-where-has-my-httpmodule-gone

public class MyMiddleware 
{ 
    private readonly RequestDelegate nextMiddleware; 
    private readonly IScriptManager _scriptManager; 

    public MyMiddleware(RequestDelegate next, IScriptManager scriptManager) 
    { 
     this.nextMiddleware = next; 
     _scriptManager = scriptManager; 
    } 
    public async Task Invoke(HttpContext context) 
    { 
     var cnt = _scriptManager.ScriptTexts.Count; 
     using (var memoryStream = new MemoryStream()) 
     { 
      var bodyStream = context.Response.Body; 
      context.Response.Body = memoryStream; 

      await _next(context); 

      var isHtml = context.Response.ContentType?.ToLower().Contains("text/html"); 
      if (context.Response.StatusCode == 200 && isHtml.GetValueOrDefault()) 
      { 
        memoryStream.Seek(0, SeekOrigin.Begin); 
        using (var streamReader = new StreamReader(memoryStream)) 
        { 
         var responseBody = await streamReader.ReadToEndAsync(); 
         // update html 
         using (var amendedBody = new MemoryStream()) 
         using (var streamWriter = new StreamWriter(amendedBody)) 
         { 
          streamWriter.Write(responseBody); 
          amendedBody.Seek(0, SeekOrigin.Begin); 
          await amendedBody.CopyToAsync(bodyStream); 
         } 
        } 
      } 
     } 
    } 
}