cURL – POST request examples

Some cURL POST request examples for self reference.

1. Normal POST

1.1 To POST without data.

$ curl -X POST http://localhost:8080/api/login/

1.2 To POST with data.

$ curl -d "username=favtuts&password=abc" http://localhost:8080/api/login/

1.3 Spring REST to accept normal POST data.

    @PostMapping("/api/login")
    public ResponseEntity<?> login(@RequestParam("username") String username,
                                    @RequestParam("password") String password) {
        //...
    }

    @PostMapping("/api/login")
    public ResponseEntity<?> login(@ModelAttribute Login login) {
        //...
    }

2. POST + Multipart

To POST with a file, add this -F file=@"path/to/data.txt"

2.1 Upload a file

$ curl -F file=@"path/to/data.txt" http://localhost:8080/api/upload/

2.2 Upload multiple files, with extra fields :

$ curl -F extraField="abc" -F files=@"path/to/data.txt" -F files=@"path/to/data2.txt"  http://localhost:8080/api/upload/multi/

2.3 Spring REST to accept POST Multipart data.

    @PostMapping("/api/upload")
    public ResponseEntity<?> uploadFile(
            @RequestParam("file") MultipartFile uploadfile) {
        //...
    }
	
    @PostMapping("/api/upload/multi")
    public ResponseEntity<?> uploadFiles(
            @RequestParam("extraField") String extraField,
            @RequestParam("files") MultipartFile[] uploadfiles) {
        //...
    }
	
    @PostMapping("/api/upload/multi2")
    public ResponseEntity<?> uploadFiles2(
            @ModelAttribute UploadModel model) {
        //...
    }

3. POST + JSON

To POST with JSON data, add this -H "Content-Type: application/json"

3.1 On Windows, escape the double quotes

c:\> curl -H "Content-Type: application/json" -X POST -d {\"username\":\"favtuts\",\"password\":\"abc\"} http://localhost:8080/api/login/

3.2 For *nix or Mac OSX, add a single quote

$ curl -H "Content-Type: application/json" -X POST -d '{"username":"favtuts","password":"abc"}' http://localhost:8080/api/login/

3.3 Spring REST to accept POST JSON data.

    @PostMapping("/api/login")
    public ResponseEntity<?> login(@RequestBody Login login) {
        //..
    }

cURL – PUT request

Example to use cURL -X PUT to send a PUT (update) request to update the user’s name and email.

Terminal

$ curl -X PUT -d 'name=favtuts&email=abc@gmail.com' http://localhost:8080/user/100

If the REST API only accepts json formatted data, try this

$ curl -X PUT -H "Content-Type: application/json" -d '{"name":"favtuts","email":"abc@gmail.com"}' http://localhost:8080/user/100

Pretty Print JSON

In cURL requests, the default JSON output is in compact format.

Terminal

curl https://api.cloudflare.com/client/v4/

{"success":false,"errors":[{"code":7000,"message":"No route for that URI"}],"messages":[],"result":null}

In cURL, we can use or pipe the json_pp to pretty print the JSON output.

Terminal

curl https://api.cloudflare.com/client/v4/ | json_pp

  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   104    0   104    0     0    400      0 --:--:-- --:--:-- --:--:--   398
{
   "errors" : [
      {
         "code" : 7000,
         "message" : "No route for that URI"
      }
   ],
   "success" : false,
   "result" : null,
   "messages" : []
}

References

1. cURL official website
2. Wikipedia – cURL
3. Ubuntu manuals – json_pp
4. Building REST services with Spring
5. cURL – Post JSON data to Spring REST
6. Spring Boot file upload example – Ajax and REST