Il 25/10/2014 10:40 UTC, Harald Groven ha scritto:

How do I get a parameter of pages using a template using the API?
E.g. extract 12345 from pages tagged with {{mytemplate|12345}}, when
mytemplate do not contain categories.

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Harald Groven

AFAIK, there is no way to get such information with the core API modules without directly adding categories via templates.
But if the target wiki uses Parsoid, you may use its API to obtain RDFa data (combined with HTML5 content) also containing transclusions in a machine-readable format. The specification is available.
Another approach could be the great mwparserfromhell Python library, widely used by bots for advanced wikitext parsing.
Please let us know your choice.