AspNet Request posted body layout renderer

Render the posted body, e.g. FORM or Ajax POST

Platforms Supported: All

Introduced in NLog.Web.AspNetCore v5.1.0 using NLogRequestPostedBodyMiddleware, and in NLog.Web v5.1.0 using NLogRequestPostedBodyModule.

⚠️ All versions before NLog.Web.AspNetCore v5.1.0 had incorrect implementation of ${aspnet-request-posted-body}, that caused random failures for the Web-Application.

Configuration Syntax

${aspnet-request-posted-body}

ASP.NET Core Setup

• NLog.Web.AspNetCore 5.1.0+
• Register NLogRequestPostedBodyMiddleware as middleware in the Configure method of Startup class
  • The middelware will activate EnablesBuffering when matching the criteria.

  // needed for  ${aspnet-request-posted-body} with an API Controller.
  // The options default to only logging a maximum of 30KB, since above that the ASP.NET Core framework
  // uses a temporary file on disk instead of a memory buffer.  
  // Also, only content types starting with ‘text/‘, or those ending with ‘xml’, ‘html’, ‘json’, or content types
  // that have the word ‘charset’ are logged, since we desire to log strings and not binary content
  // Those can be overridden in the options if necessary.  But typically the default options should be adequate.
  app.UseMiddleware<NLog.Web.NLogRequestPostedBodyMiddleware>
        (new NLog.Web.NLogRequestPostedBodyMiddlewareOptions());

Full Example:

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseExceptionHandler("/Home/Error");
            // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
            app.UseHsts();
        }
        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseRouting();
        app.UseAuthorization();

        // needed for  ${aspnet-request-posted-body} with an API Controller.
        app.UseMiddleware<NLog.Web.NLogRequestPostedBodyMiddleware>(
            new NLog.Web.NLogRequestPostedBodyMiddlewareOptions());

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllerRoute(
                name: "default",
                pattern: "{controller=Home}/{action=Index}/{id?}");
        });

NLogRequestPostedBodyMiddleware Options

• int MaxContentLength

  • The maximum request posted body that will be captured. Defaults to 30 KB.
  • HttpRequest.EnableBuffer() is documented as using memory buffer until 30 KB, then this will use temp files on disk, which could have a performance impact.

• IList<KeyValuePair<string,string>> AllowContentTypes

  • The Key is the prefix value such as ‘text’.
  • The Value is the suffix value such as ‘html’.
  • The default contents of this property are:
    • 'application/', 'json'
    • 'application/', 'xml'
    • 'application/', 'html'
    • 'text/', ''
    • '', 'charset'

• Predicate<HttpContext> ShouldCapture()

  • By default this method returns true if
    • The content length is not null and is <= MaxContentLength
    • The content type must match one of the entries in the AllowContentTypes List.
    • For a match the ContentType must StartsWith the Key, case insensitive, and also have an IndexOf the Value, case insensitive.
    • An empty string for the Key or for the Value acts as a wildcard match.
    • The method has the HttpContext as the parameter, so a user wishing to override this property should have all the properties required to implement an override.

See also: HTTP-Request-Logging

ASP.NET Setup

• NLog.Web 5.1.0+

To use this target with NLog.Web, then you need to enable the HttpModule NLogRequestPostedBodyModule:

  public class MyGlobalApplication : System.Web.HttpApplication
  {
     public static IHttpModule NLogRequestPostedBody = new NLog.Web.NLogRequestPostedBodyModule();

     public override void Init()
     {
         base.Init();
         NLogRequestPostedBody.Init(this);
     }
  }

See also: HTTP-Request-Logging