Citations are only recognized when they're parsed as markdown.
@key in a code block or attribute won't be parsed.

You could use the pandoc Lua 'read' function to parse the
contents of your attribute as Markdown and then do something with that.

Carsten Gips <cagix...@gmail.com> writes:

> I've tried to resolve this manually by extracting this piece with a Lua
> filter, converting it into a new document and running Pandoc plus Citeproc
> on this temporary document with `pandoc.utils.run_json_filter`, retrieving
> the processed citation and putting it back as codeblock caption in the
> original document. However, this approach seems not to be working.
>
> To narrow this down further, I wrote a short document (`test.md`, see
> attachment) and a Lua filter (`codecite.lua`, see attachment). (To make it
> even shorter, in the Lua filter I simply replace the text block of the
> document with a similar new block).
>
> But this does not seem to work. The call `pandoc -L codecite.lua test.md -t
> json` returns only
>
> ```json
> {"pandoc-api-version":[1,22],"meta":{"references":{"t":"MetaList","c":[{"t":"MetaMap","c":{"author":{"t":"MetaList","c":[{"t":"MetaMap","c":{"family":{"t":"MetaInlines","c":[{"t":"Str","c":"Wuppie"}]}}}]},"id":{"t":"MetaInlines","c":[{"t":"Str","c":"FOO"}]},"title":{"t":"MetaInlines","c":[{"t":"Str","c":"Lorem"},{"t":"Space"},{"t":"Str","c":"Ipsum"}]}}}]}},"blocks":[{"t":"Para","c":[{"t":"Str","c":"see
> [@FOO]"}]}]}
> ```
> i.e. the citation is not resolved.
>
> However, if I run Pandoc directly on this document, i.e `pandoc -t json
> --citeproc test.md`, the result is as expected:
>
> ```json
> {"pandoc-api-version":[1,22],"meta":{"references":{"t":"MetaList","c":[{"t":"MetaMap","c":{"author":{"t":"MetaList","c":[{"t":"MetaMap","c":{"family":{"t":"MetaInlines","c":[{"t":"Str","c":"Wuppie"}]}}}]},"id":{"t":"MetaInlines","c":[{"t":"Str","c":"FOO"}]},"title":{"t":"MetaInlines","c":[{"t":"Str","c":"Lorem"},{"t":"Space"},{"t":"Str","c":"Ipsum"}]}}}]}},"blocks":[{"t":"Para","c":[{"t":"Str","c":"see"},{"t":"Space"},{"t":"Cite","c":[[{"citationId":"FOO","citationPrefix":[],"citationSuffix":[],"citationMode":{"t":"NormalCitation"},"citationNoteNum":1,"citationHash":0}],[{"t":"Str","c":"(Wuppie,"},{"t":"Space"},{"t":"Str","c":"n.d.)"}]]}]},{"t":"Div","c":[["refs",["references","csl-bib-body","hanging-indent"],[]],[{"t":"Div","c":[["ref-FOO",["csl-entry"],[]],[{"t":"Para","c":[{"t":"Str","c":"Wuppie."},{"t":"Space"},{"t":"Str","c":"n.d."},{"t":"Space"},{"t":"Span","c":[["",[],[]],[{"t":"Str","c":"“"},{"t":"Str","c":"Lorem"},{"t":"Space"},{"t":"Str","c":"Ipsum"},{"t":"Str","c":"."},{"t":"Str","c":"”"}]]}]}]]}]]}]}
> ```
>
> Clearly I'm missing something here. But what is it? Can you please advise?
>
>
> PS: `pandoc --version`: pandoc 2.14.2
>
> Carsten Gips schrieb am Donnerstag, 9. September 2021 um 10:27:36 UTC+2:
>
>> Dear all,
>>
>> I'm trying to resolve citations inside attributes, i.e.
>>
>> ```{.c caption="nice, see [@KEY]"}
>> ...
>> ```
>>
>> Pandoc and Citeproc are currently not handling citations inside am
>> attribute like in the example. How can I resolve these citations anyway?
>>
>> Thanks,
>> Carsten
>>
>
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> ---
> references:
> - author:
> - family: Wuppie
> id: FOO
> title: Lorem Ipsum
> ---
> see [@FOO]