jq · lesson 28 of 32 · Variables & functions

Recursion: .., paths, walk

.. visits every value in the document, at any depth. Pair it with a type filter such as numbers or strings. walk(f) rewrites every value, children first.

Example 1Every number, anywhere

Document

{ "a": [1, [2, 3]], "b": { "c": "x" } }

Query

[.. | numbers]

.. Recursive descent: emit the document and everything nested inside it, at any depth.
numbers A filter that lets only numbers through.

Result

[1,2,3]

Try it in the playground

Example 2Rewrite every number

Document

{ "a": [1, [2, 3]], "b": { "c": "x" } }

Query

walk(if type == "number" then . * 10 else . end)

walk( Apply the filter to every value in the document, children first.
if type == "number" Test each value's type…
then . * 10 else . end …multiply numbers by 10 and leave everything else unchanged.

Result

{"a":[10,[20,30]],"b":{"c":"x"}}

Try it in the playground

Good to know

[paths] lists every location as an array of keys and indexes — ["a"], ["a",0], … — and getpath(["a",0]) reads one.