ImageFile alt-description validation attribute

A customer wanted to improve their quality of having meta descriptive texts on all their published images but it was ok that it could take some time to get it into place (they are forced to review and republish pages on a regular basis) so thought that a validation attribute would do the trick.

I vaguely remebered that I did something like this a long time a go which I had (nov 2015) but that didn't handle images added in Xhtml-properties which was needed in this case. I found a solution that had solved a similiar problem but did handle it on actual rendering which used HtmlAgilitypack to handle the check for xthml-editors.

So I updated my validation attribute and I have published it as a Gist. ImageValidatorGist.

The validation attribute checks contentreference, ContentArea and XhtmlEditor properties for images and check if they have a description property with value and if not returns an error. Since a image-file added to a XhtmlEditor gets the filename name as alt-text we need to compare the alt-text to the file-name and if equal we interpret that as not set even if the image file it self might have a descripton set.