curl --request POST \
  --url https://demo.onlinebillingform.com/api/v2/invoice/update-invoice \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "invoice_id": 123,
  "duedate": "<string>",
  "customer_id": 123,
  "comments": "<string>",
  "record.item": [
    "<string>"
  ],
  "record.description": [
    "<string>"
  ],
  "record.price": [
    "<string>"
  ],
  "record.quantity": [
    "<string>"
  ],
  "record.tax_class": [
    "<string>"
  ],
  "record.tax": [
    "<string>"
  ]
}
'

import requests

url = "https://demo.onlinebillingform.com/api/v2/invoice/update-invoice"

payload = {
    "invoice_id": 123,
    "duedate": "<string>",
    "customer_id": 123,
    "comments": "<string>",
    "record.item": ["<string>"],
    "record.description": ["<string>"],
    "record.price": ["<string>"],
    "record.quantity": ["<string>"],
    "record.tax_class": ["<string>"],
    "record.tax": ["<string>"]
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    invoice_id: 123,
    duedate: '<string>',
    customer_id: 123,
    comments: '<string>',
    'record.item': ['<string>'],
    'record.description': ['<string>'],
    'record.price': ['<string>'],
    'record.quantity': ['<string>'],
    'record.tax_class': ['<string>'],
    'record.tax': ['<string>']
  })
};

fetch('https://demo.onlinebillingform.com/api/v2/invoice/update-invoice', 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://demo.onlinebillingform.com/api/v2/invoice/update-invoice",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'invoice_id' => 123,
    'duedate' => '<string>',
    'customer_id' => 123,
    'comments' => '<string>',
    'record.item' => [
        '<string>'
    ],
    'record.description' => [
        '<string>'
    ],
    'record.price' => [
        '<string>'
    ],
    'record.quantity' => [
        '<string>'
    ],
    'record.tax_class' => [
        '<string>'
    ],
    'record.tax' => [
        '<string>'
    ]
  ]),
  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://demo.onlinebillingform.com/api/v2/invoice/update-invoice"

	payload := strings.NewReader("{\n  \"invoice_id\": 123,\n  \"duedate\": \"<string>\",\n  \"customer_id\": 123,\n  \"comments\": \"<string>\",\n  \"record.item\": [\n    \"<string>\"\n  ],\n  \"record.description\": [\n    \"<string>\"\n  ],\n  \"record.price\": [\n    \"<string>\"\n  ],\n  \"record.quantity\": [\n    \"<string>\"\n  ],\n  \"record.tax_class\": [\n    \"<string>\"\n  ],\n  \"record.tax\": [\n    \"<string>\"\n  ]\n}")

	req, _ := http.NewRequest("POST", 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.post("https://demo.onlinebillingform.com/api/v2/invoice/update-invoice")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"invoice_id\": 123,\n  \"duedate\": \"<string>\",\n  \"customer_id\": 123,\n  \"comments\": \"<string>\",\n  \"record.item\": [\n    \"<string>\"\n  ],\n  \"record.description\": [\n    \"<string>\"\n  ],\n  \"record.price\": [\n    \"<string>\"\n  ],\n  \"record.quantity\": [\n    \"<string>\"\n  ],\n  \"record.tax_class\": [\n    \"<string>\"\n  ],\n  \"record.tax\": [\n    \"<string>\"\n  ]\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://demo.onlinebillingform.com/api/v2/invoice/update-invoice")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"invoice_id\": 123,\n  \"duedate\": \"<string>\",\n  \"customer_id\": 123,\n  \"comments\": \"<string>\",\n  \"record.item\": [\n    \"<string>\"\n  ],\n  \"record.description\": [\n    \"<string>\"\n  ],\n  \"record.price\": [\n    \"<string>\"\n  ],\n  \"record.quantity\": [\n    \"<string>\"\n  ],\n  \"record.tax_class\": [\n    \"<string>\"\n  ],\n  \"record.tax\": [\n    \"<string>\"\n  ]\n}"

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

{
  "success": true
}

{
  "success": false,
  "errors": "Invalid API Key"
}

{
  "success": false,
  "errors": "Insufficient permissions for this endpoint."
}

{
  "success": false,
  "errors": {
    "id": [
      "The id field is required."
    ]
  }
}