curl PUT with variables containing JSON data

Question

I want to use curl to PUT data. This works:

curl -X PUT --data '{ "xy": [0.6476, 0.2727] }' "http://"

I have a couple of bash variables that I'd like to use in place of the literals:

$key="xy"
$value="[0.6476, 0.2727]"

I've tried replacing the literals with quoted vars, but I get an error 'parameter not available'. I've tried combinations of nested and escaped quotes, but I am not getting anywhere.

Answer 1

This works for me with Node :

key="xy"
value="[0.6476, 0.2727]"
jsonData=$(node -e "console.log(JSON.stringify({$key: $value}))")
#jsonData output is: {"xy":[0.6476,0.2727]}

curl -X PUT --data $jsonData "http://"

But this only works for Node.js Developer or you have Node environment installed.

Answer 2

Well this works for me :

 $ key='foo' 
 $ value='[ bar, bar ]' 
 $ echo "{ \"$key\": $value }"
 { "foo": [ bar, bar ] }

So this should work for you as well :

curl -X PUT --data "{ \"$key\": $value }" "http://google.com.uy"

Let me know if it helps!

Answer 3

Using jq (1.6 or later), use the --jsonargs option to take multiple JSON-encoded values as a JSON array accessible via $ARGS.positional :

$ key=xy
$ value=(0.6476 0.2727)
$ jq -n '{($k): $ARGS.positional}' --arg k "$key" --jsonargs "${value[@]}"
{
  "xy": [
    0.6476,
    0.2727
  ]
}

--jsonargs must come last, so that all remaining arguments are treated as values in the desired array. We use --jsonargs rather than --args so that you get an array of floating-point values, rather than an array of strings.

Once you have jq working, you pipe its output to curl , which uses - as the argument to --data to read the data from the pipe.

jq -n '{($k): $ARGS.positional}' --arg k "$key" --jsonargs "${value[@]}" |
   curl -X PUT --data - "http://"