Feature request: make @sh work on objects

[Sec42]

Currently jq can not apply the "sh" escaping to objects:

>jq -nr '{foo: "bar",baz: "test"}|@sh'
jq: error (at <unknown>): object ({"foo":"bar...) can not be escaped for shell

It would be nice if it would "just work" and output assignments similar to:

>jq -nr '{foo: "bar",baz: "test"}|to_entries|.[]|"\(.key)=\(.value|@sh)"'
foo='bar'
baz='test'

[b0o]

I actually had this need as well, so I wrote a few helper functions:

def to_entries_recursive(p):
  if isempty(p) then
    {
      root: true,
      type: type,
      path: [],
      value: to_entries_recursive([])
    }
  elif type == "array" or type == "object" | not then . else
    to_entries | map([.value, p + [.key]] as [$val, $path] |
      {
        key: .key,
        type: $val | type,
        $path,
        value: $val | to_entries_recursive($path),
      }
    )
  end
;
def to_entries_recursive: to_entries_recursive(empty);

def flatten_tree:
  def _handle_node:
    if .type == "array" or .type == "object" | not then
      { (.path | join("__")): .value }
    else
      .value | map(_handle_node) | add
    end
  ;
  to_entries_recursive | _handle_node
;

def shell_fmt:
  if type != "object" then
    @sh
  else
    flatten_tree | to_entries | map("\(.key)=\(.value | @sh)")
  end
;

Usage:

jq 'shell_fmt'
   {"foo": 42}
=> ["foo=42"]

jq 'shell_fmt'
   {"name": {"first": "Rob", "last": "Tables", "title": "Sr."}, "kids": ["Roberta", "Bobby"]}
=> ["name__first='Rob'","name__last='Tables'","name__title='Sr.'","kids__0='Roberta'","kids__1='Bobby'"]

jq 'shell_fmt'
   42
=> ["42"]

jq 'shell_fmt'
   [1,3,5,7]
=> ["1 3 5 7"]

jq 'shell_fmt'
   {"age": 99.9, "foo":[1,"bar",{"qux": [1,9,{"key": "huh?", "value": "idk lol"}]}], "name": "bob"}
=> ["age=99.9","foo__0=1","foo__1='bar'","foo__2__qux__0=1","foo__2__qux__1=9","foo__2__qux__2__key='huh?'","foo__2__qux__2__value='idk lol'","name='bob'"]

It's not perfect:

• arrays within objects are not represented the same as arrays on their own:

  jq 'shell_fmt'
     [1,3,5,7]
  => ["1 3 5 7"]
  
  jq 'shell_fmt'
     {"arr": [1,3,5,7]}
  => ["arr__0=1","arr__1=3","arr__2=5","arr__3=7"]
  

• doesn't sanitize object keys:

  jq 'shell_fmt'
     '{"tell it like it is!": "ok sure thing"}'
  => ["tell it like it is!='ok sure thing'"]
  

• due to the way keys/indices are serialized with __ as a separator, an object's key can "overwrite" other ones:

  jq 'shell_fmt'
     {"a": [1,2,3], "b": {"aay": "yo"}, "a__0": -42, "b__aay": "naw"}
  => ["a__0=-42","a__1=2","a__2=3","b__aay='naw'"]
  

• probably more issues

If you trust the source of your json and know reasonably well its structure won't have these issues, this should work in a pinch. With some more work, maybe it could be made semi-robust?

Otherwise, I don't recommend it for anything important, but maybe it can give you some ideas!

[garthk]

See also #789?