Passing bash variable to jq

Question

Consider also passing in the shell variable (EMAILID) as a jq variable (here also EMAILID, for the sake of illustration):

   projectID=$(jq -r --arg EMAILID "$EMAILID" '
        .resource[]
        | select(.username==$EMAILID) 
        | .id' file.json)

Postscript

For the record, another possibility would be to use jq's env function for accessing environment variables. For example, consider this sequence of bash commands:

[email protected]  # not exported
EMAILID="$EMAILID" jq -n 'env.EMAILID'

The output is a JSON string:

"[email protected]"

I resolved this issue by escaping the inner double quotes

projectID=$(cat file.json | jq -r ".resource[] | select(.username==\"$EMAILID\") | .id")

Posting it here as it might help others. In string it might be necessary to pass the quotes to jq. To do the following with jq:

.items[] | select(.name=="string")

in bash you could do

EMAILID=$1
projectID=$(cat file.json | jq -r '.resource[] | select(.username=='\"$EMAILID\"') | .id')

essentially escaping the quotes and passing it on to jq

Little unrelated but I will still put it here, For other practical purposes shell variables can be used as -

value=10
jq  '."key" = "'"$value"'"' file.json

It's a quote issue, you need :

projectID=$(
  cat file.json | jq -r ".resource[] | select(.username=='$EMAILID') | .id"
)

If you put single quotes to delimit the main string, the shell takes $EMAILID literally.

"Double quote" every literal that contains spaces/metacharacters and every expansion: "$var", "$(command "$var")", "${array[@]}", "a & b". Use 'single quotes' for code or literal $'s: 'Costs $5 US', ssh host 'echo "$HOSTNAME"'. See
http://mywiki.wooledge.org/Quotes
http://mywiki.wooledge.org/Arguments
http://wiki.bash-hackers.org/syntax/words

Another way to accomplish this is with the jq "--arg" flag. Using the original example:

#!/bin/sh

#this works ***
projectID=$(cat file.json | jq -r '.resource[] | 
select(.username=="[email protected]") | .id')
echo "$projectID"

[email protected]

# Use --arg to pass the variable to jq. This should work:
projectID=$(cat file.json | jq --arg EMAILID $EMAILID -r '.resource[] 
| select(.username=="$EMAILID") | .id')
echo "$projectID"

See here, which is where I found this solution: https://github.com/stedolan/jq/issues/626