downcase a value in JSON

Question

I have a json file and I'm looking to lowercase PART of a value - I can jq the value and lower case the string but how do I ensure this new lowercase value gets added back into the whole file?

jq '.[].Id' file.json | awk '{print tolower($0)}'  

the above only lower cases the ID value's but now I also need to write those back into their correct spots.

Answer 1

Use the update operator with ascii_downcase builtin.

jq '.[].Id |= ascii_downcase' file