jq

jq-things.sh

# Adding a key/value pair to an object based on a condition
#
# Let's say you have a sample object like:
#
# ```json
# {
#   "session_id": "some-id-1",
#   "timestamp": "some-timestamp",
#   "events": [
#     {
#       "type": "cpu_usage"
#     },
#     {
#       "type": "cpu_usage"
#     },
#     {
#       "type": "cpu_usage"
#     },
#     {
#       "type": "exception",
#       "exception": {
#          "name": "whatever",
#          "exceptions": [],
#          "threads": [],
#          "device_locale": "something"
#       }
#     },
#     {
#       "type": "cpu_usage"
#     },
#     {
#       "type": "cpu_usage"
#     }
#   ]
# }
# ```
# 
# To add {"foo": "bar"} to the "exception" object. do this..

jq '.events |= map(if .type == "exception" then .exception += {"foo": "bar} else . end)' input.json

# To update input.json in-place, with sponge (https://joeyh.name/code/moreutils/)

jq '.events |= map(if .type == "exception" then .exception += {"foo": "bar} else . end)' input.json | sponge input.json