What can you do about the various warnings?
For the warning "no plugin for Crossref ...", this is what happened internally:
This happens when we don't have a hard coded
plugin for that specific publisher within this packge
(use ft_get_ls() to see what hard coded publisher plugins
we have), but we do have generic functions for Crossref and
ftdoi that are also tried and may get a result. You
are welcome to open up an issue at
https://github.com/ropensci/fulltext/issues to discuss
publisher specific plugins.
For the warning "you may not have access to ... or an error occurred" we've likely tried to get the full text but either an error occurred (which can be a lot of things), or you don't have access to the full text.
If you think the problem may be that you don't have access, check whether you are on an IP address that has access to the full text, and if you're not, get on one that does - most likely by being on campus/etc. or through a VPN.
For the warning "... was not found or may be a DOI for a part of an article" this happens for certain publishers (e.g., PLOS) that issue DOIs for parts of articles (e.g., abstract, body, supplements) - in which case it doesn't make sense to get full text of, for example, supplements.
For the warning "no link found from Crossref", this happens when we've gone through the route of searching for a full text URL from the Crossref API, and there wasn't one, so we stop searching and give that warning.
The Crossref Text and Data Mining service ended at the end of 2020.
We only check for the CROSSREF_TDM environment variable when you request
articles from Elsevier and Wiley as those two publishers were the only
major publishers that used the Crossref TDM service. If we detect the key
we'll throw a warning - you should probably remove your CROSSREF_TDM
key as the service is no longer operational.
This document is in relation to the function ft_get()