How do I POST JSON data with cURL?

I use Ubuntu and installed cURL on it. I want to test my Spring REST application with cURL. I wrote my POST code at the Java side. However, I want to test it with cURL. I am trying to post a 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;
}

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.

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

For Windows, having a single quote for the -d value did not work for me, but it did work after changing to 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

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

It's a wrapper round CURL which 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 http://127.0.0.1:8080/data #Sets up resty to point at your endpoing
$ GET /blogs.json                  #Gets http://127.0.0.1:8080/data/blogs.json
                                   #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][1]

[1]: https://github.com/micha/resty#setting-the-default-curl-options "Setting default RESTY options"

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.

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

You can use postman to convert to CURL

Note:

The latest Postman version has some UI upgrades and now the code link is available in the sidebar.

I just run into the same problem. I could solve it by specifying

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

This worked well for me.

curl -X POST --data @json_out.txt http://localhost:8080/

Where,

-X Means the http verb.

--data Means the data you want to send.

You can use Postman with its intuitive GUI to assemble your cURL command.

0. Install and Start Postman
1. Type in your URL, Post Body, Request Headers etc. pp.
2. Click on Code
3. Select cURL from the drop-down list
4. copy & paste your cURL command

Note: There are several options for automated request generation in the drop-down list, which is why I thought my post was neccessary in the first place.

HTTPie is a recommended alternative to curl because you can do just

$ http POST http://example.com/some/endpoint name=value name1=value1

It speaks JSON by default and will handle both setting the necessary header for you as well encoding data as valid JSON. There is also:

Some-Header:value

for headers, and

name==value

for query string parameters. If you have a large chunk of data, you can also read it from a file have it be JSON encoded:

 field[email protected]

Using CURL Windows, try this:

curl -X POST -H "Content-Type:application/json" -d "{\"firstName\": \"blablabla\",\"lastName\": \"dummy\",\"id\": \"123456\"}" http-host/_ah/api/employeeendpoint/v1/employee

This worked well for me, additionally using BASIC authentication:

curl -v --proxy '' --basic -u Administrator:password -X POST -H "Content-Type: application/json"
        --data-binary '{"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://httpbin.org/post

Of course, you should never use BASIC authentication without SSL and a checked certificate.

I ran into this again today, using Cygwin's cURL 7.49.1 for Windows... And when using --data or --data-binary with a JSON argument, cURL got confused and would interpret the {} in the JSON as a URL template. Adding a -g argument to turn off cURL globbing fixed that.

See also https://stackoverflow.com/questions/8333920/passing-a-url-with-brackets-to-curl.

If you're testing a lot of JSON send/responses against a RESTful interface, you may want to check out the Postman plug-in for Chrome (which allows you to manually define web service tests) and its Node.js-based Newman command-line companion (which allows you to automate tests against "collections" of Postman tests.) Both free and open!

You could also put your JSON content in a file and pass it to curl using the --upload-file option via standard input, like this:

 echo 'my.awesome.json.function({"do" : "whatever"})' | curl -X POST "http://url" -T -

This worked for me:

curl -H "Content-Type: application/json" -X POST -d @./my_json_body.txt http://192.168.1.1/json

I know, a lot has been answered to this question but wanted to share where I had the issue of:

> curl -X POST http://your-server-end-point -H "Content-Type: application/json" > -d @path-of-your-json-file.json

See, I did everything right, Only one thing - "@" I missed before the JSON file path.

I found one relevant go-to document on internet - https://gist.github.com/subfuzion/08c5d85437d5d4f00e58

Hope that might help the few. thanks

Here is another way to do it, if you have dynamic data to be included.

#!/bin/bash

version=$1
text=$2
branch=$(git rev-parse --abbrev-ref HEAD)
repo_full_name=$(git config --get remote.origin.url | sed 's/.*:\/\/github.com\///;s/.git$//')
token=$(git config --global github.token)

generate_post_data()
{
  cat <<EOF
{
  "tag_name": "$version",
  "target_commitish": "$branch",
  "name": "$version",
  "body": "$text",
  "draft": false,
  "prerelease": false
}
EOF
}

echo "Create release $version for repo: $repo_full_name branch: $branch"
curl --data "$(generate_post_data)" "https://api.github.com/repos/$repo_full_name/releases?access_token=$token"

TL;DR:

Use the holy trinity, jo + curl + jq (or fx):

jo value=30 type="Tip 3" targetModule="Target 3" configurationGroup=null name="Configuration Deneme 3" description=null identity="Configuration Deneme 3" | \
curl --json @- \
    -X POST \
    http://localhost:8080/xx/xxx/xxxx | \
jq

This will cover necessary headers that were missing: no need to explicitly define the Content-Type and Accept headers.

The new curl way with --json

Early March 2022, curl released a new command line parameter --json with version 7.82.0. This allows for a shortcut to send through JSON and eliminating the need to define the Content-Type that you had missing and Accept headers as these are automatically assumed, hence reducing risk of mistakes:

curl --json '{"tool": "curl"}' https://example.com/

But wait... there is more. Instead of defining the json parameter as a string to the curl command line, use the nifty jo CLI tool to define JSON as series of key value pairs and pipe the output through curl. Using jo only to define your JSON, it works this way:

 > jo -p 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
{
   "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
}

Let's showcase this now with a similar curl command of yours but without extra headers and using jo + jq for nice output:

jo value=30 type="Tip 3" targetModule="Target 3" configurationGroup=null name="Configuration Deneme 3" description=null identity="Configuration Deneme 3" | \
curl --json @- \
    -X POST \
    http://localhost:8080/xx/xxx/xxxx | \
jq

Example with a free API

Using a free (but limited) API for demonstration:

> jo name=Grogu gender=male email=frog.menace@jedi.edu status=active | \ 
curl --json @- \ 
    -H $env:GOREST_TOKEN \
    -XPATCH "https://gorest.co.in/public/v2/users/1138" | \
jq

The output has a pretty format thanks to jq:

{
  "email": "[email protected]",
  "name": "Grogu",
  "gender": "male",
  "status": "active",
  "id": 1138
}

Use -d option to add payload

curl -X POST \
http://<host>:<port>/<path> \
-H 'Accept: application/json' \
-H 'Content-Type: application/json' \
-d '{
"foo": "bar",
"lorem": "ipsum"
}'

In addition:

use -X POST to use POST method

use -H 'Accept: application/json' to add accept type header

use -H 'Content-Type: application/json' to add content type header

I am using the below format to test with a web server.

use -F 'json data'

Let's assume this JSON dict format:

{
    'comment': {
        'who':'some_one',
        'desc' : 'get it'
    }
}

###Full example

curl -XPOST your_address/api -F comment='{"who":"some_one", "desc":"get it"}'

This worked for me for on Windows10

curl -d "{"""owner""":"""sasdasdasdasd"""}" -H "Content-Type: application/json" -X  PUT http://localhost:8080/api/changeowner/CAR4

I made a tool called fetcher for this. It can send requests and format curl snippets:

Here's an example:

Example output:

curl -XGET -H "Accept: application/json" -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"

For PowerShell I've used:

curl.exe -H "Content-Type: application/json" --data "@content.json" http://localhost:8080/appname/path

Where content.json was the name of the json file on my local containing the request, and curl.exe instead of just curl not to use the alias for Invoke-WebRequest.

Or if you want to specify directly the JSON:

curl.exe -H "Content-Type: application/json" --data '{\"username\":\"xyz\",\"password\":\"xyz\"}' http://localhost:8080/appname/path

ISSUE is HERE

HTTP/1.1 415 Unsupported Media Type

Server Login can't interpret the Media Type of this request, so it is parsing it as text/html

> The media type of any resource is declared in the Content-Type > property of the request header

"accept" ... header will fail this request, so the following is required for any JSON request to be sent i.e. content-type

-H 'content-type: application/json'

Suppose data and URL are something like this

> {"email": "[email protected]","password": "123456"}

> http://localhost:5000/api/login

then in LINUX

curl  http://localhost:5000/api/login  -H 'content-type: application/json'  -d '{"email": "[email protected]", "password": "123456"}'

in WINDOWS (single quotes around params will not work)

curl  http://localhost:5000/api/login  -H "content-type: application/json"  -d "{\"email\": \"user@admin.com\", \"password\": \"123456\"}"

-X POST key is not required when -d {.....} is present in command

For Put request

-X PUT 

Based on https://stackoverflow.com/a/57369772/2391795 answer, here is what I did to this on GitHub Actions. It was a bit tricky due to the EOF tag.

My goal was to send an HTTP call once a Vercel deployment was finished (similar to a webhook).

Hoping this real-world example might help other people.

  send-webhook-callback-once-deployment-ready:
    name: Invoke webhook callback url defined by the customer (Ubuntu 18.04)
    runs-on: ubuntu-18.04
    needs: await-for-vercel-deployment
    steps:
      - uses: actions/checkout@v1 # Get last commit pushed - See https://github.com/actions/checkout
      - name: Expose GitHub slug/short variables # See https://github.com/rlespinasse/github-slug-action#exposed-github-environment-variables
        uses: rlespinasse/[email protected] # See https://github.com/rlespinasse/github-slug-action
      - name: Expose git environment variables and call webhook (if provided)
        # Workflow overview:
        #  - Resolves webhook url from customer config file
        #  - If a webhook url was defined, send a
        run: |
          MANUAL_TRIGGER_CUSTOMER="${{ github.event.inputs.customer}}"
          CUSTOMER_REF_TO_DEPLOY="${MANUAL_TRIGGER_CUSTOMER:-$(cat vercel.json | jq --raw-output '.build.env.NEXT_PUBLIC_CUSTOMER_REF')}"

          VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK=$(cat vercel.$CUSTOMER_REF_TO_DEPLOY.staging.json | jq --raw-output '.build.env.VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK')

          # Checking if a webhook url is defined
          if [ -n "$VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK" ]; then
            # Run script that populates git-related variables as ENV variables
            echo "Running script populate-git-env.sh"
            . ./scripts/populate-git-env.sh

            echo "Resolved git variables:"
            echo "'GIT_COMMIT_SHA': $GIT_COMMIT_SHA"
            echo "'GIT_COMMIT_REF': $GIT_COMMIT_REF"
            echo "'GIT_COMMIT_TAGS': $GIT_COMMIT_TAGS"

            # Generates JSON using a bash function - See https://stackoverflow.com/a/57369772/2391795
            # "End Of File" must be at the beginning of the line with no space/tab before or after - See https://stackoverflow.com/a/12909284/2391795
            # But, when executed by GitHub Action, it must be inside the "run" section instead
            generate_post_data() {
              cat <<EOF
            {
              "MANUAL_TRIGGER_CUSTOMER": "${MANUAL_TRIGGER_CUSTOMER}",
              "CUSTOMER_REF": "${CUSTOMER_REF_TO_DEPLOY}",
              "STAGE": "staging",
              "GIT_COMMIT_SHA": "${GIT_COMMIT_SHA}",
              "GIT_COMMIT_REF": "${GIT_COMMIT_REF}",
              "GIT_COMMIT_TAGS": "${GIT_COMMIT_TAGS}",
              "GITHUB_REF_SLUG": "${GITHUB_REF_SLUG}",
              "GITHUB_HEAD_REF_SLUG": "${GITHUB_HEAD_REF_SLUG}",
              "GITHUB_BASE_REF_SLUG": "${GITHUB_BASE_REF_SLUG}",
              "GITHUB_EVENT_REF_SLUG": "${GITHUB_EVENT_REF_SLUG}",
              "GITHUB_REPOSITORY_SLUG": "${GITHUB_REPOSITORY_SLUG}",
              "GITHUB_REF_SLUG_URL": "${GITHUB_REF_SLUG_URL}",
              "GITHUB_HEAD_REF_SLUG_URL": "${GITHUB_HEAD_REF_SLUG_URL}",
              "GITHUB_BASE_REF_SLUG_URL": "${GITHUB_BASE_REF_SLUG_URL}",
              "GITHUB_EVENT_REF_SLUG_URL": "${GITHUB_EVENT_REF_SLUG_URL}",
              "GITHUB_REPOSITORY_SLUG_URL": "${GITHUB_REPOSITORY_SLUG_URL}",
              "GITHUB_SHA_SHORT": "${GITHUB_SHA_SHORT}"
            }
          EOF
            }

            echo "Print generate_post_data():"
            echo "$(generate_post_data)"

            echo "Calling webhook at '$VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK'"
            echo "Sending HTTP request (curl):"
            curl POST \
              "$VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK" \
              -vs \
              --header "Accept: application/json" \
              --header "Content-type: application/json" \
              --data "$(generate_post_data)" \
              2>&1 | sed '/^* /d; /bytes data]$/d; s/> //; s/< //'

            # XXX See https://stackoverflow.com/a/54225157/2391795
            # -vs - add headers (-v) but remove progress bar (-s)
            # 2>&1 - combine stdout and stderr into single stdout
            # sed - edit response produced by curl using the commands below
            #   /^* /d - remove lines starting with '* ' (technical info)
            #   /bytes data]$/d - remove lines ending with 'bytes data]' (technical info)
            #   s/> // - remove '> ' prefix
            #   s/< // - remove '< ' prefix

          else
            echo "No webhook url defined in 'vercel.$CUSTOMER_REF_TO_DEPLOY.staging.json:.build.env.VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK' (found '$VERCEL_DEPLOYMENT_COMPLETED_WEBHOOK')"
          fi

• -H to send something like content-type or auth token in header
• -d here put your data
• finally add site link

Note don't forget to add auth token (if you have) for authentication credentials

curl -X POST -H 'Content-Type: application/json' -H 'Authorization: Token 2de403987713595a7955a9b4655b9e206d4294b3' -d '{"title":"Post test with curl", "body": "test body"}' http://127.0.0.1:8000/api/v1/feeds/

You can cat the contents of a json file to curl via the --data-raw parameter

curl 'https://api.com/route' -H 'Content-Type: application/json' --data-raw "$(cat ~/.json/payload-2022-03-03.json | grep -v '^\s*//')"

Note: comments in the json file are filtered out via grep -v '^\s*//'

You can also pass the data to curl via stdin using grep or cat

grep -v '^\s*//' ~/.json/payload-2022-03-03.json | curl 'https://api.com/route' -H 'Content-Type: application/json' -d @-

cat ~/.json/payload-2022-03-03.json | grep -v '^\s*//' | curl 'https://api.com/route' -H 'Content-Type: application/json' -d @-