jq - How to select objects based on a 'whitelist' of property values

Question

Since an example is worth a thousand words, say I have the following JSON stream:

{"a": 0, "b": 1}
{"a": 2, "b": 2}
{"a": 7, "b": null}
{"a": 3, "b": 7}

How can I keep all the objects for which the .b property is one of [1, 7] (in reality the list is much longer so I don't want to do select(.b == 1 or .b == 7)). I'm looking for something like this: select(.b in [1, 7]), but I couldn't find what I'm looking for in the man page.

Answer 1

Doing $value in $collection could be achieved using the pattern select($value == $collection[]). A more efficient alternative would be select(any($value == $collection[]; .)) So your filter should be this:

[1, 7] as $whitelist | select(any(.b == $whitelist[]; .))

Having the array in a variable has its benefits as it lets you change the whitelist easily using arguments.

$ jq --argjson whitelist '[2, 7]' 'select(any(.b == $whitelist[]; .))'