[ILUG-Webdev] PHP - converting HTML entities outside tags

[Lee Hosty]

I'm using HTMLFilter (http://linux.duke.edu/projects/mini/htmlfilter/) to
safely allow certain HTML tags as user input to be displayed later. I use
htmlspecialchars() to display this text in a textarea during editting, so
everything displays as valid XHTML at this stage, without any user
confusion.

However if the user inputs a HTML entity (&, " or ' for example), it gets
saved as is to the DB - and displays fine as XHTML in a textarea - but
when output to a browser at the viewing stage (as opposed to the editting
stage) - these bare entities are not valid XHTML and need converting. I
can do this either at the saving to DB stage or just before outputting to
browser.

However I can't blindly convert all HTML entities found to their relative
values anymore using htmlspecialchars(), as some of the entities may be
inside the tags that the user has input, and I don't want these converted.

ie. user inputs <a href="whatever.html" target='new_target'>"my amazin'
links & stuff"</a>

needs to be converted to <a href="whatever.html"
target='new_target'>&quot;my amazin&#039; links &amp; stuff&quot;</a>

Any ideas? I'm new to PHP and would rather not re-invent any wheels.

Thanks in advance