POST multiple files with -d in curl - bash

Question

I'm using curl to create several classifications. I have written the json for the many classifications and they are in one folder. I would like to create all the classifications in one go. But using curl I can only create them one at a time. How could I make them in one request?
curl -u admin:admin -H "Content-Type: application/json" -X POST -d #pii.json http://127.0.0.1:21000/api/atlas/v2/types/typedefs
The curl manual for -d says 'Multiple files can also be specified'. How can I do this? All my attempts have failed.
Do I need a bash script instead? If so, could you help me - I'm not a coder and I'm struggling without an example!
Thanks in advance.

Answer 1

You probably don't want to use multiple -d with JSON data since curl concatenates multiple ones with a & in between. As described in the man page for -d/--data:
If any of these options is used more than once on the same command
line, the data pieces specified will be merged together with a
separating &-symbol. Thus, using '-d name=daniel -d skill=lousy' would
generate a post chunk that looks like 'name=daniel&skill=lousy'.
You can however easily and conveniently pass several files on stdin to let curl use them all in one go:
cat a.json b.json c.json | curl -d#- -u admin:admin -H "Content-Type: application/json" http://127.0.0.1:21000/api/atlas/v2/types/typedefs
(please note that -X POST has no place on a command line that uses -d)

Answer 2

I found the following to work in the end:
<fileToUpload.dat xargs -I % curl -X POST -T "{%}" -u admin:admin -H "Content-Type: application/json" http://127.0.0.1:21000/api/atlas/v2/types/typedefs
Where fileToUpload.dat contained a list of the .json files.
This seemed to work over Daniel's answer, probably due to the contents of the files. Hopefully this is useful to others if Daniel's solution doesn't work for them.

Answer 3

I needed to upload all the *.json files from a folder via curl and I made this little script.
nfiles=*.json
echo "Enter user:"
read user
echo "Enter password:"
read -s password
for file in $nfiles
do
echo -e "\n----$file----"
curl --user $user:$password -i -X POST "https://foo.bar/foo/bar" -H "Content-Type: application/json" -d "#$file"
done
Maybe fits your needs.