curl --request PATCH \
  --url https://{defaultHost}/v1/shipments/{id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "shipment": {
    "label_file_type": "PNG"
  }
}
'

import requests

url = "https://{defaultHost}/v1/shipments/{id}"

payload = { "shipment": { "label_file_type": "PNG" } }
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.patch(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'PATCH',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({shipment: {label_file_type: 'PNG'}})
};

fetch('https://{defaultHost}/v1/shipments/{id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://{defaultHost}/v1/shipments/{id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "PATCH",
  CURLOPT_POSTFIELDS => json_encode([
    'shipment' => [
        'label_file_type' => 'PNG'
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://{defaultHost}/v1/shipments/{id}"

	payload := strings.NewReader("{\n  \"shipment\": {\n    \"label_file_type\": \"PNG\"\n  }\n}")

	req, _ := http.NewRequest("PATCH", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.patch("https://{defaultHost}/v1/shipments/{id}")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"shipment\": {\n    \"label_file_type\": \"PNG\"\n  }\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://{defaultHost}/v1/shipments/{id}")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Patch.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"shipment\": {\n    \"label_file_type\": \"PNG\"\n  }\n}"

response = http.request(request)
puts response.read_body

{
  "id": "4a443bc0-1218-451c-ae6a-8e9aa742a9d5",
  "object": "shipment",
  "carrier": null,
  "carrier_messages": [],
  "contact_validations": null,
  "dimensions": {
    "length": 10,
    "width": 8,
    "height": 5,
    "unit": "in"
  },
  "eta": null,
  "inherit_weight": false,
  "label_file_type": "PNG",
  "label_url": null,
  "live_mode": true,
  "rates": [],
  "selected_rate": null,
  "shipping_date": 1782432000,
  "status": "draft",
  "tracking_number": null,
  "tracking_status": null,
  "tracking_url": null,
  "weight": "2.0",
  "weight_unit": "lb",
  "from_contact": "9c7fcff1-147d-4d04-b9e1-e79594d7ff12",
  "fulfillment": "a18be342-6300-428c-b02d-a34a28e5b958",
  "parcel_template": null,
  "shipping_provider": "aec3c3aa-0352-497b-8c2c-4b4e2eb9243c",
  "to_contact": "c7012e3d-da82-48f5-9681-43ccb22e2457",
  "created_at": 1782485899,
  "updated_at": 1782485899
}