How to Fake a Media Library Item and return an image from external provider instead

Question

The scenario is the following:

For a single component we're getting the html content from an external provider. Including images. For each image we have to call a separate endpoint of the external provider. In return we get the Binary data with the http header "content-type:image/jpeg.

So basically I have this link <img src="mydomain.com/-/city/images/test.jpg" />

But this image does not exist and never will be in Sitecore. Instead for every image that starts with "-/city" I need to get the image from somewhere else. My Idea was to overwrite the MediaProvider where I set the Url to an existing Media Item. Once that is assigned I want to call the endpoint and return the mediastream from my endpoint. I've followed this blog post: https://sitecorejumpstart.wordpress.com/2020/02/28/override-the-sitecore-media-provider/

But already failed here:

public override MediaRequest ParseMediaRequest(HttpRequest request) as I cannot change the called Url to something else in the request.

Any idea how or if this is doable at all? I'm using SC 9.1.1 btw with SxA

Answer 1

You wrote in your question:

every image that starts with -/city I need to get the image from somewhere else

In my opinion, if Sitecore has nothing to do with those urls, let's not even try to handle it by Sitecore. That's a waste of resources only.

Instead, create a handler for -/city/* urls and register it in web.config. Something like this should do the trick:

<add verb="" path="-/city/*" type="My.Assembly.Namespace.CityMediaHandler, My.Assembly.Namespace" />

Potentially you will need to add /-/city/ to IgnoreUrlPrefixes:

<setting name="IgnoreUrlPrefixes" value="/-/city/|/sitecore/default.aspx|/trace.axd|...