Transforming the name of key deeper in the JSON structure with jq

Question

I have following json:

{
  \"vertices\": [
    {
      \"__cp\": \"foo\",
      \"__type\": \"metric\",
      \"__eid\": \"foobar\",
      \"name\": \"Undert         


        

Answer 1

The following program works with jq 1.4 or jq 1.5. It uses walk/1 to remove leading underscores from any key, no matter where it occurs in the input JSON.

The version of ltrim provided here uses recurse/1 for efficiency and portability, but any suitable substitute may be used.

def ltrim(c):
  reduce recurse( if .[0:1] == c then .[1:] else null end) as $x 
    (null; $x);

# Apply f to composite entities recursively, and to atoms
def walk(f):
 . as $in
 | if type == "object" then
      reduce keys[] as $key
        ( {}; . + { ($key):  ($in[$key] | walk(f)) } ) | f
  elif type == "array" then map( walk(f) ) | f
  else f
  end;

.vertices = .nodes
| del(.nodes)
| (.vertices |= walk(
      if type == "object"
      then with_entries( .key |= ltrim("_") )
      else .
      end ))