Instead this worked. Not sure exactly why the other works and not
select.
athlete.leagues.collect(&:league_id)
because “.select” returns only those elements that return true to an
evaluation, while “.collect” returns the result of the block passed to
every element. Have a look at the Enumerable and Array api pages. http://www.ruby-doc.org/core-1.9.3/Enumerable.html
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