How to POST JSON data with cURL?

Query explained:

I use Ubuntu and installed cURL on it. I want to test my Spring REST application with cURL. I wrote my POST code on the Java side. However, I want to test it with cURL. I am trying to post JSON data. Example data is like this:

{"value":"30","type":"Tip 3","targetModule":"Target 3","configurationGroup":null,"name":"Configuration Deneme 3","description":null,"identity":"Configuration Deneme 3","version":0,"systemId":3,"active":true}

I use this command:

curl -i \
    -H "Accept: application/json" \
    -H "X-HTTP-Method-Override: PUT" \
    -X POST -d "value":"30","type":"Tip 3","targetModule":"Target 3","configurationGroup":null,"name":"Configuration Deneme 3","description":null,"identity":"Configuration Deneme 3","version":0,"systemId":3,"active":true \
    http://localhost:8080/xx/xxx/xxxx

It returns this error:

HTTP/1.1 415 Unsupported Media Type
Server: Apache-Coyote/1.1
Content-Type: text/html;charset=utf-8
Content-Length: 1051
Date: Wed, 24 Aug 2011 08:50:17 GMT

The error description is this:

The server refused this request because the request entity is in a format not supported by the requested resource for the requested method ().

Tomcat log: “POST /ui/webapp/conf/clear HTTP/1.1” 415 1051

What is the right format of the cURL command?

This is my Java side PUT code (I have tested GET and DELETE and they work):

@RequestMapping(method = RequestMethod.PUT)
public Configuration updateConfiguration(HttpServletResponse response, @RequestBody Configuration configuration) { //consider @Valid tag
    configuration.setName("PUT worked");
    //todo If error occurs response.sendError(HttpServletResponse.SC_NOT_FOUND);
    return configuration;
}

How to POST JSON data with cURL?

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.

For windows, single quotes around JSON did not work and I ended up escaping double quotes:

curl -X POST -H "Content-Type: application/json" -d "{ \"key1\": \"value1\" }" http://localhost:3000/api/method

What is JSON(in case you still have confusion)?

JSON stands for JavaScript Object Notation. JSON is a lightweight format for storing and transporting data. JSON is often used when data is sent from a server to a web page. JSON is “self-describing” and easy to understand.

Alternative solution:

Try to put your data in a file, say body.json and then use

curl -H "Content-Type: application/json" --data @body.json http://localhost:8080/ui/webapp/conf

Answer #2:

For Windows, having a single quote for the -d value did not work for me, but it did work after changing to a double quote. Also, I needed to escape double quotes inside curly brackets.

That is, the following did not work:

curl -i -X POST -H "Content-Type: application/json" -d '{"key":"val"}' http://localhost:8080/appname/path

But the following worked:

curl -i -X POST -H "Content-Type: application/json" -d "{\"key\":\"val\"}" http://localhost:8080/appname/path

Answer #3:

You might find resty useful: https://github.com/micha/resty

It’s a wrapper around CURL that simplifies command line REST requests. You point it to your API endpoint, and it gives you PUT and POST commands. (Examples adapted from the homepage)

$ resty  #Sets up resty to point at your endpoing
$ GET /blogs.json                  #Gets 
                                   #Put JSON
$ PUT /blogs/2.json '{"id" : 2, "title" : "updated post", "body" : "This is the new."}'
                                   # POST JSON from a file
$ POST /blogs/5.json < /tmp/blog.json

Also, it’s often still necessary to add the Content Type headers. You can do this once, though, to set a default, of add config files per-method per-site: Setting default RESTY options.

Answer #4:

It worked for me using:

curl -H "Accept: application/json" -H "Content-type: application/json" -X POST -d '{"id":100}' http://localhost/api/postJsonReader.do

It was happily mapped to the Spring controller:

@RequestMapping(value = "/postJsonReader", method = RequestMethod.POST)
public @ResponseBody String processPostJsonData(@RequestBody IdOnly idOnly) throws Exception {
        logger.debug("JsonReaderController hit! Reading JSON data!"+idOnly.getId());
        return "JSON Received";
}

IdOnly is a simple POJO with an id property.

Post JSON data from cURL – Answer #5:

As an example, create a JSON file, params.json, and add this content to it:

[
    {
        "environment": "Devel",
        "description": "Machine for test, please do not delete!"
    }
]

Then you run this command:

curl -v -H "Content-Type: application/json" -X POST --data @params.json -u your_username:your_password http://localhost:8000/env/add_server

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