jq returning null as string if the json is empty

Question

I'm running this command do get a value from the json;

addr=$(./xuez-cli getnetworkinfo | jq -r '.localaddresses[0].address')

and it works just fine.

BUT if this .localaddresses[0].address part empty or doesn't even exist, jq sets the addr variable as null like this; addr=null

and I want to check if the json is empty/null and run some other command instead of parsing it as null string.

I couldn't find a way to work this around. How can I do this?

Answer 1

Something useful I found for shell scripts was:

jq '.foo // empty'

Which returns the match if successful, and the empty string if unsuccessful. So in bash I use:

addr=$(./xuez-cli getnetworkinfo | jq -r '.localaddresses[0].address // empty')

if [[ ! -z "$addr" ]]; then
    # do something
fi

Ref: https://github.com/stedolan/jq/issues/354#issuecomment-43147898 https://unix.stackexchange.com/questions/451479/jq-print-for-null-values