How can I put integer as an argument in jq?

Question

I have been trying to use jq to parse a json file returned from the aws cli, but I'm stuck with the problem of referencing an array using the index number. I need to do this because I want to export a text file describing the security groups in a specific format, including all the inbound and outbound rules.

for (( i=1; i<=groupCount; i++ )) ; 
do
    echo $i
    echo $(echo "$input" | jq --arg i $i '.SecurityGroups[$i]')
done

This returns an error:

1
jq: error (at <stdin>:189): Cannot index array with string "1"

2
jq: error (at <stdin>:189): Cannot index array with string "2"

3
jq: error (at <stdin>:189): Cannot index array with string "3"

Is there any way around this?

Answer 1

You would either have to use the command line arg --argjson or fromjson filter to convert the argument to a number. Arrays are may only be indexed by ints and using --arg keeps the input as a string.

$ jq --argjson i "$i" '.SecurityGroups[$i]'
$ jq --arg i "$i" '.SecurityGroups[$i|fromjson]'