A post says
I am trying to find my posts whose titles contain idiom ...
I guess it's not grammatical to use "whose" there, as posts are not humankind.
I would have said
I am trying to find my posts, titles of which contain idiom ...
I am worrying about whether it is idiomatic to say it that way.
Google searching gets only one hit.
Could someone please give a hint? Thanks in advance.