Sending a POST request via curl has issues with double quotes

Question

So, in-order to send a POST request to gists (github), you can do something like this as seen in https://gist.github.com/caspyi...

curl --user "user" -X POST --data '{"description":"Created via API","public":"true","files":{"file1.txt":{"content":"Demo"}}' https://api.github.com/gists

But, in the above example, the file name and the content of the file are hard coded which is the part ..file1.txt":{"content":"Demo"}..

I am replacing the above part with my variable $file":{"content":"$content"} but initialize the variable, the json request must be enclosed in double quotes, which I did as

curl --user "user" -X POST --data "{\"description\":\"Created via API\",\"public\":\"true\",\"files\":{\"$file\":{\"content\":\"$content\"}}' https://api.github.com/gists

But this does not work, I get json error.

{
  "message": "Problems parsing JSON",
  "documentation_url": "https://developer.github.com/v3/gists/#create-a-gist"
}

Even, if I replaced all the escaped double-quotes with \' single quotes.

Does anyone know how to include a variable inside this json request? btw: I have used all headers such as

 -H "Content-Type: application/json; charset=UTF-8" 

and many combinations to validate the request but to no avail

UPDATE.

This is what the entire content looks like.

function gist_controller(){
    content=$(cat $1)
    DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
    read -p "enter your password - " pass 
    public="false"
    gist_content=$(cat $1)
    curl --user "samserayo"  -H "Content-Type: application/json; charset=UTF-8" -X POST -d  "{ 'description': 'Created via API', 'public': 'true', 'files':{ ' '$1 ':{ 'content': '$gist_content'}}" https://api.github.com/gists
}

Answer 1

You don't show what value you have set for $file or $content. What do those both expand out to? It's likely one, or the other, or both, contain characters the JSON parser doesn't like. Most likely, something inside the variable expansion value needs to be further escaped or encoded before submission to the JSON parser through curl.

Have you EXPORTed the environment variables?

Try:

echo "$file $content";

to make sure they are both set as you expect them to be.

Answer 2

You didn't specify what shell you are using, but anything within double-quotes is subject to shell filename expansion. In particular, {} has meaning to most shells. That's the reason that the example you cited used single quotes to wrap the whole thing.

Shell escapes are tricky, and sometimes it seems impossible to get what you want. Honestly, in cases like this I would write a Python script to call curl, where I know the shell isn't "helping" me out.

Answer 3

You have to put the entire string inside double quotes ". And you need to escape quotes inside the string (not convert them into other types of quotes!).

So instead of:

"{ 'description': 'Created via API', 'public': 'true', 'files':{ ' '$1 ':{ 'content': '$gist_content'}}"

You want:

"{ \"description\": \"Created via API\", \"public\": \"true\", \"files\" : { \"$1\" : { \"content\": \"$gist_content\"}}}"

You should probably test with echo and make sure the string is exactly correct.