SXA Media Handler PDF Caching Override

MediaRequestHeaderProcessor.cs

using Sitecore.Diagnostics;
using Sitecore.XA.Foundation.MediaRequestHandler.Pipelines.MediaRequestHeaders;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace SCBasics.Foundation.Caching.Pipelines
{
    public class MediaRequestHeaderProcessor
    {
        public void Process(MediaRequestHeadersArgs args)
        {   
            try
            {
                Assert.ArgumentNotNull(args, nameof(args));
                var media = args.Media;
                var cache = args.Context.Response.Cache;

                int maxAgeInSeconds =
                    Sitecore.Configuration.Settings.GetIntSetting("MediaRequest.CachingOverride.MaxAgeInSeconds", 0);
                string mimeTypeToApplyCache =
                    Sitecore.Configuration.Settings.GetSetting("MediaRequest.CachingOverride.MimeTypeToApplyCache", "application");
                string httpCacheability =
                    Sitecore.Configuration.Settings.GetSetting("MediaRequest.CachingOverride.HttpCacheability", "NoCache");
                string cacheExtension =
                    Sitecore.Configuration.Settings.GetSetting("MediaRequest.CachingOverride.CacheExtension", "no-cache");

                if (media.MimeType.StartsWith(mimeTypeToApplyCache
                    , StringComparison.OrdinalIgnoreCase))
                {
                    cache.SetMaxAge(TimeSpan.FromSeconds(maxAgeInSeconds));

                    if (!string.IsNullOrWhiteSpace(httpCacheability))
                    {
                        // Please make sure there is no typo and value should be from above list of possibe values
                        // This will be mainly owned by Developers - So, if Dev makes any typo - This will throw error - Which is intentional
                        var httpCacheabilityValue = (HttpCacheability)
                        Enum.Parse(typeof(System.Web.HttpCacheability), httpCacheability, true);
                        if (httpCacheability != null)
                            cache.SetCacheability(httpCacheabilityValue);
                    }
                    if (!string.IsNullOrWhiteSpace(cacheExtension))
                        cache.AppendCacheExtension(cacheExtension);
                }
            }
            catch (Exception exception)
            {
                // Log it and swallow it
                Log.Error("Something went wrong while setting cache-control headers for media file", exception, this);
            }
        }
    }
}

SCBasics.Foundation.MediaRequest.CachingOverride.config

<?xml version="1.0"?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/" xmlns:role="http://www.sitecore.net/xmlconfig/role/">
  <sitecore>
    <!-- Thanks! https://ggullentops.blogspot.com/2021/01/sitecore-media-cache-headers-pdf.html-->
    <!--NOTE : This pipeline is to add additional cache-control headers to disable caching for specific mimetype -->
    <settings>
      <!--MimeType To Apply Cache  
      https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/MIME_types/Common_types
      We are doint it for application - Which covers most of the documents-->
      <setting name="MediaRequest.CachingOverride.MimeTypeToApplyCache" value="application"/>

      <!--//
      // Summary:
      //     Sets the Cache-Control: no-cache header. Without a field name, the directive
      //     applies to the entire request and a shared (proxy server) cache must force a
      //     successful revalidation with the origin Web server before satisfying the request.
      //     With a field name, the directive applies only to the named field; the rest of
      //     the response may be supplied from a shared cache.
      NoCache = 1,
      //
      // Summary:
      //     Default value. Sets Cache-Control: private to specify that the response is cacheable
      //     only on the client and not by shared (proxy server) caches.
      Private = 2,
      //
      // Summary:
      //     Specifies that the response is cached only at the origin server. Similar to the
      //     System.Web.HttpCacheability.NoCache option. Clients receive a Cache-Control:
      //     no-cache directive but the document is cached on the origin server. Equivalent
      //     to System.Web.HttpCacheability.ServerAndNoCache.
      Server = 3,
      //
      // Summary:
      //     Applies the settings of both System.Web.HttpCacheability.Server and System.Web.HttpCacheability.NoCache
      //     to indicate that the content is cached at the server but all others are explicitly
      //     denied the ability to cache the response.
      ServerAndNoCache = 3,
      //
      // Summary:
      //     Sets Cache-Control: public to specify that the response is cacheable by clients
      //     and shared (proxy) caches.
      Public = 4,
      //
      // Summary:
      //     Indicates that the response is cached at the server and at the client but nowhere
      //     else. Proxy servers are not allowed to cache the response.
      ServerAndPrivate = 5
      
      NOTE : Please make sure there is no typo and value should be from above list of possibe values-->
      <setting name="MediaRequest.CachingOverride.HttpCacheability" value="NoCache"/>
      <!--Appends the specified text to the Cache-Control HTTP header.-->
      <setting name="MediaRequest.CachingOverride.CacheExtension" value=""/>
      
      <!--Max Age In Seconds-->
      <setting name="MediaRequest.CachingOverride.MaxAgeInSeconds" value="0"/>
      
    </settings>
    <!-- Added to Disable PDF Browser Caching -->
    <pipelines>
      <mediaRequestHeaders>
        <processor type="SCBasics.Foundation.Caching.Pipelines.MediaRequestHeaderProcessor, SCBasics.Foundation.Caching" />
      </mediaRequestHeaders>
    </pipelines>
  </sitecore>
</configuration>

web.config.transform

<handlers>
      <add xdt:Transform="Replace" xdt:Locator="Match(name)" name="Sitecore.MediaRequestHandler" verb="*" path="sitecore_media.ashx" type="Sitecore.XA.Foundation.MediaRequestHandler.MediaRequestHandler, Sitecore.XA.Foundation.MediaRequestHandler" />
</handlers>

<!--Optional-->