It looks like the output of the Citoid API varies considerably depending on what type of URL is used. For example, if the URL is for a book chapter (http://link.springer.com/chapter/10.1007/11926078_68) it will return the chapter title as "title" and the book title as "bookTitle", but if the URL is for a book (https://books.google.com/books?id=k-XBMNVRfw4C), it will return the book title as "title". So we'll need to be careful to look at the itemType before deciding how to map the values.

FWIW, it seems that Mr.Z-Man (Alex) has possibly retired from Wikipedia. He hasn't edited any projects or touched any of his tools in GitHub for the past couple months. If someone wanted to work on this, they might have to folk the code.

In the editor, I lookup a DOI and get no result (10.1109/ase.2011.6100176)

In the console, I see that the AJAX Call is made to reftoolbar, and it returns nothing:
https://tools.wmflabs.org/reftoolbar/lookup.php?doi=10.1109%2FASE.2011.6100176&template=journal&format=ref

On the contrary, a call to the citation API would return the correct result:
https://en.wikipedia.org/api/rest_v1/data/citation/zotero/10.1109%2fASE.2011.6100076

How to use the right URL is the editor gadget?

I believe you have to use the "URL" field for citoid results in reftoolbar.
I'm not sure who is running the reftoolbar labs instance but maybe it's
broken. Putting the doi in the URL field should work for the time being.

Probably there should be a separate bug filed for the doi field issue.

Thanks for your answer. We make progress.

There is a difference depending on the editor:

• In the "Source Editor", all AJAX calls are made against https://tools.wmflabs.org/reftoolbar/lookup.php
• In the "Visual Editor", the AJAX calls go to https://en.wikipedia.org/api/rest_v1/data/citation/

Yet, it does not work in the Visual Editor, because of an encoding problem, see T207518

RefToolbar queries Citoid only for ISBN and URL queries, see https://github.com/alexz-enwp/reftoolbar/blob/master/lookup.php#L328

This pull-request proposes that RefToolbar also uses Citoid for DOI calls: https://github.com/alexz-enwp/reftoolbar/pull/1

Yes, you have to put the DOI in the URL field if you want a response from
citoid - a bit confusing. Plausibly we should enable citoid for the DOI
field as well.