rails equivalent of sql 'in ' operator -

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Assume that our models are A, B, and C

A 1: N B1 : N to C

How do I use a query to return a subset of C such that the owner of each C is one of the A's owned B?

Essentially but this is unanswered

Must have:

A has_one C ,: = through = B

and then you will be able to AC

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