Get or default function in jq?

Question

Assuming there is a json file:

{
  \"columns\": {
    \"id\": {
      \"required\": true,
      \"type\": \"integer\"
    },
    \"name\": {
      \"required         


        

Answer 1

Use alternative operator (//):

$ jq '.columns.description | .required // false' file
false

Answer 2

If the field "required" does not exist, it should return the default value false.

To implement that functionality literally, you would use has/1 rather than //, e.g.:

   .columns.id
   | if has("required") then .required else false end

If the .required field is known never to be specified as null, then the two techniques (using has as above and using // false) are equivalent.

getOrDefault/2

You'd almost surely never define such a function, but since you ask:

def getOrDefault($key; $default):
  if has($key) then .[$key] else $default end;

(NB: The argument separator in jq is ;.)