jq - select objects with given key name

Question

I've got an arbitrary structure with many levels, etc. I need to select all objects that contain a key named updateDate. How do I do that with jq? I came up with one way but it also produces errors on invalid data types when it visits a leaf which I have to grep out:

jq 'recurse(.[]) | has("updateDate")' | grep -Fv error

I don't really understand how to also check for types or leaves and I suspect there is a simpler way to achieve what I want?

score 26 · Accepted Answer · answered Jun 19 '14 at 06:44

26

In 1.4 you can just:

jq '..|.updateDate?'

If you're stuck with 1.3 you can use a longer program like so:

jq 'recurse(if type == "array" or type = "object" then .[] else empty end) | if type == "object" then .updateDate else empty end'

answered Jun 19 '14 at 06:44

user2259432

2,239
1
19
15

2

This will error out when the structure includes arrays. Adding `|objects|` in the middle fixes it, I think. – Tgr Sep 26 '17 at 00:27
Note if you want to filter empty arrays then you could follow https://stackoverflow.com/a/26196653/308851 `jq '..|.updateDate?|select(length>0)'` – chx Jun 12 '19 at 07:46

score 9 · Answer 2 · answered Dec 07 '18 at 19:54

The accepted answer also produces null for every object that doesn't have the key.

What worked for me was:

jq '..|objects|.updateDate//empty'

The .updateDate//empty part means: if .updateDate is null (or false), skip it entirely.

This of course wouldn't work if you expect your key to have values of false or null. In that case, use this:

jq '..|objects|select(has("updateDate"))|.updateDate'

score 1 · Answer 3 · answered Jun 19 '14 at 06:44

1

Not tested: how about jq 'recurse(.[]?) | objects | has("updateDate")' ?

answered Jun 19 '14 at 06:44

hobbs

223,387
19
210
288

1

recurse(.[]?) | objects | select(has("a")) – Eric Hartford Jul 07 '14 at 21:49

jq - select objects with given key name

3 Answers3

Linked