jq - How do I print a parent value of an object when I am already deep into the object's children?

x3nr0s picture x3nr0s · Aug 1, 2016 · Viewed 16.3k times · Source

Say I have the following JSON, stored in my variable jsonVariable.

{
    "id": 1,
    "details": {
        "username": "jamesbrown",
        "name": "James Brown"
    }
}

I parse this JSON with jq using the following:

echo $jsonVariable | jq '.details.name | select(.name == "James Brown")'

This would give me the output

James Brown

But what if I want to get the id of this person as well? Now, I'm aware this is a rough and simple example - the program I'm working with at the moment is 5 or 6 levels deep with many different JQ functions other than select. I need a way to select a parent's field when I am already 5 or 6 layers deep after carrying out various methods of filtering.

Can anyone help? Is there any way of 'going in reverse', back up to the parent? (Not sure if I'm making sense!)

Answer

user3899165 picture user3899165 · Aug 1, 2016

For a more generic approach, save the value of the "parent" element at the detail level you want, then pipe it at the end of your filter:

jq '. as $parent | .details.name | select(. == "James Brown") | $parent'

Of course, for the trivial case you expose, you could omit this entirely:

jq 'select(.details.name == "James Brown")'

Also, consider that if your selecting filters return many matches for a single parent object, you will receive a copy of the parent object for each match. You may wish to make sure your select filters only return one element at the parent level by wrapping all matches below parent level into an array, or to deduplicate the final result with unique.