When you make a POST request, you have to encode the data that forms the body of the request in some way.
HTML forms provide three methods of encoding.
application/x-www-form-urlencoded
(the default)
multipart/form-data
text/plain
Work was being done on adding application/json
, but that has been abandoned.
(Other encodings are possible with HTTP requests generated using other means than an HTML form submission. JSON is a common format for use with web services and some still use SOAP.)
The specifics of the formats don't matter to most developers. The important points are:
When you are writing client-side code:
- use
multipart/form-data
when your form includes any <input type="file">
elements
- otherwise you can use
multipart/form-data
or application/x-www-form-urlencoded
but application/x-www-form-urlencoded
will be more efficient
When you are writing server-side code:
- Use a prewritten form handling library
Most (such as Perl's CGI->param
or the one exposed by PHP's $_POST
superglobal) will take care of the differences for you. Don't bother trying to parse the raw input received by the server.
Sometimes you will find a library that can't handle both formats. Node.js's most popular library for handling form data is body-parser which cannot handle multipart requests (but has documentation that recommends some alternatives which can).
If you are writing (or debugging) a library for parsing or generating the raw data, then you need to start worrying about the format. You might also want to know about it for interest's sake.
application/x-www-form-urlencoded
is more or less the same as a query string on the end of the URL.
multipart/form-data
is significantly more complicated but it allows entire files to be included in the data. An example of the result can be found in the HTML 4 specification.
text/plain
is introduced by HTML 5 and is useful only for debugging — from the spec: They are not reliably interpretable by computer — and I'd argue that the others combined with tools (like the Network Panel in the developer tools of most browsers) are better for that).
You need to set your content-type to application/json. But -d
(or --data
) sends the Content-Type application/x-www-form-urlencoded
, which is not accepted on Spring's side.
Looking at the curl man page, I think you can use -H
(or --header
):
-H "Content-Type: application/json"
Full example:
curl --header "Content-Type: application/json" \
--request POST \
--data '{"username":"xyz","password":"xyz"}' \
http://localhost:3000/api/login
(-H
is short for --header
, -d
for --data
)
Note that -request POST
is optional if you use -d
, as the -d
flag implies a POST request.
On Windows, things are slightly different. See the comment thread.
Best Answer
Steps to use 'Multipart/form-data ' in Postman