Curl with multiline of JSON - bash

Question

Consider the curl command below, is it possible to allow newline in JSON (without the minify) and execute directly in bash (Mac/Ubuntu)
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
-d \
'
{
"field1": "test",
"field2": {
"foo": "bar"
}
}'
When I run the command above, seems error occurred at the second {
How to fix the above command?
Updated: actually I was able to run the command without issue previously, not sure why problem happen recently.

Answer 1

I remembered another way to do this with a "Here Document" as described in the Bash man page and detailed here. The #- means to read the body from STDIN, while << EOF means to pipe the script content until "EOF" as STDIN to curl. This layout may be easier to read than using separate files or the "echo a variable" approach.
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: application/json; charset=utf-8' \
--data-binary #- << EOF
{
"field1": "test",
"field2": {
"foo": "bar"
}
}
EOF
NOTE: Use the --trace <outfile> curl option to record exactly what goes over the wire. For some reason, this Here Document approach strips newlines. (Update: Newlines were stripped by curl -d option. Corrected!)

Answer 2

Along the lines of Martin's suggestion of putting the JSON in a variable, you could also put the JSON in a separate file, and then supply the filename to -d using curl's # syntax:
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
-d #myfile.json
The disadvantage is obvious (2 or more files where you used to have one.) But on the plus side, your script could accept a filename or directory argument and you'd never need to edit it, just run it on different JSON files. Whether that's useful depends on what you are trying to accomplish.

Answer 3

For some reason, this Here Document approach strips newlines
#eric-bolinger the reason the Heredoc strips newlines is because you need to tell your Heredoc to preserve newlines by quoting the EOF:
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
-d #- <<'EOF'
{
"field1": "test",
"field2": {
"foo": "bar"
}
}
EOF
Notice the single-ticks surrounding EOF the first time it's defined, but not the second.

Answer 4

You should use outer double quotes, and the escape all inner quotes like this:
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
-d \
"
{
\"field1\": \"test\",
\"field2\": {
\"foo\": \"bar\"
}
}"

Answer 5

You could assign your json to a var:
json='
{
"field1": "test",
"field2": {
"foo": "bar"
}
}'
Now you can forward this to curl using stdin:
echo $json | curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
-d #-

Answer 6

I think this can be an answer
curl -0 -v -X POST http://www.example.com/api/users \
-H "Expect:" \
-H 'Content-Type: text/json; charset=utf-8' \
--data-raw '
{
"field1": "test",
"field2": {
"foo": "bar"
}
}'