[TYPO3] Templavoila and additional where clause

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Hello list,

I have TYPO3 site in 3 languages. I use templavoila on this site. And I have
a question is it possible to add where clause to content that templavoila
shows?
My problem is that i added 1 field to tt_content table named "city". Also, I
use get var "city", and if this 2 values match (or city from GP is in list
of tt_content's city field ) then I want that content element to be shown,
else do not show. And if there is no city in tt_content, then show this
record for all cities.
I think I can do it with additional where to tt_content table. Or maybe
there is some other solutions?
Thanks in advance.

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