Comment database entry is empty

[sebastiangreger]

Sorry for this being a rather unspecific issue report. I spent over an hour tracing the problem, but do not seem to find the key to solving it.

I am using wordpress-webmention and wordpress-semantic-linkback, and webmentions in general work fine. However, today I received a webmention from this source to this target, which created a comment in the database, but all fields are empty.

Debugging, I was able to trace the issue to

wordpress-semantic-linkbacks/includes/class-linkbacks-mf2-handler.php

Line 159 in 29dcda5

if ( empty( $entries ) ) {

- the function returns an empty array, which means that $commentdata, which still contained all the webmention's data before it was called is then empty.

The function gets called by filter semantic_linkbacks_commentdata - before the line

wordpress-semantic-linkbacks/includes/class-linkbacks-handler.php

Line 202 in 29dcda5

$commentdata = apply_filters( 'semantic_linkbacks_commentdata', $commentdata );

$commentdata is fine, after the call it is empty.

Erasing the entire comment data and creating an empty comment (maybe due to a malformed markup? ...I lack the background to dig deeper) is probably not desired behaviour?

[pfefferle]

It is indeed a problem of the markup, because Marc does not use h-entry on his website, but you are right, it should not save empty fields in this case. Thanks for reporting.

[pfefferle]

Hmm... but it seems that Marc does not use any possible fallback (OpenGraph, meta-description) so there is no way to get any data. But the plugin should show a message like "... mentioned this ... on ..." or show a facepile?!?

[edent]

This is what's causing the issues in pfefferle/wordpress-webmention#289

[edent]

Replacing return array(); with return $commentdata; seems to fix it. That allows it to be an "unenhanced" Webmention.

[pfefferle]

Good point... If there are no MF(2)s in the site it would be blank otherwise!