希望 ASP.NET Core 中间件在 MVC Razor 视图引擎之后运行

Question

在 MVC Razor 视图引擎处理数据后，我希望在 ASP.NET Core 中运行 MiddleWare 模块。我可以让它运行，但它似乎没有收集到所有数据。我有一个更新 DI 对象集合的 Tag Helper，但是当中间件运行时，DI 对象的集合是空的。我的 startup.cs 看起来像这样：

    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?}");
        });
    }

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);

我确实得到了我想要的 HTML，但我的 DI 中的集合似乎没有得到更新。

*** 注释 - 可能但不工作的结果过滤器

        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，在请求管道中的 mvc 之后无法运行中间件。如果要操作剃刀输出，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需要直接包围的任何逻辑 查看执行或格式化程序执行。结果过滤器可以替换或 修改负责产生 回应。

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

另请参阅如何通过过滤器使用依赖注入 https://docs.microsoft.com/en-us/aspnet/core/mvc/controllers/filters#dependency-injection

更新

我无法让它与结果过滤器一起工作（它可以工作 json 结果，但不能工作 viewresult）。

但是我发现了一个很好的中间件示例：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);
                        }
                    }
            }
        }
    }
}