Recursive search values by key

Question

I have a JSON like this:

{ 
  "A": { "error": null },
  "B": { "C": {"error": "error string"}},
  "C": { "D": {"error": null}},
  "D": { "error": "err str"}
}

end I want to find all values of error keys which are not null.

For my example it should return

"error string"
"err str"

How can I do it? Is it possible with jq?

I tried things like `jq 'select(.error!=null)' file.json` but it doesn't search recursively. — Ardling, Jul 19 '16 at 13:14

score 39 · Accepted Answer · answered Jul 19 '16 at 14:09

Use .. to iterate recursively, and get all the .error values. If they're null, remove them:

jq '.. | .error? // empty'

Alternatively, instead of using empty you can select the elements that are strings with strings:

jq '.. | .error? | strings'

score 3 · Answer 2 · answered Aug 06 '17 at 01:13

3

Here is a solution that uses tostream and select

  tostream
| select(length==2 and .[0][-1]=="error" and .[1]!=null) as [$p,$v]
| $v

answered Aug 06 '17 at 01:13

jq170727

I wasn't previously aware of the `tostream`/`fromstream` functionality. That dramatically simplifies working with arbitrarily nested documents. Thanks! – larsks Jul 25 '23 at 21:14

2 Answers2