curl --request POST \
  --url https://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id} \
  --header 'Content-Type: application/json' \
  --data '
{
  "namespace": "<string>",
  "handle": "<string>",
  "value": "<string>",
  "name": "<string>",
  "is_index": "<string>"
}
'

import requests

url = "https://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id}"

payload = {
    "namespace": "<string>",
    "handle": "<string>",
    "value": "<string>",
    "name": "<string>",
    "is_index": "<string>"
}
headers = {"Content-Type": "application/json"}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: JSON.stringify({
    namespace: '<string>',
    handle: '<string>',
    value: '<string>',
    name: '<string>',
    is_index: '<string>'
  })
};

fetch('https://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{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://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id}",
  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([
    'namespace' => '<string>',
    'handle' => '<string>',
    'value' => '<string>',
    'name' => '<string>',
    'is_index' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "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://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id}"

	payload := strings.NewReader("{\n  \"namespace\": \"<string>\",\n  \"handle\": \"<string>\",\n  \"value\": \"<string>\",\n  \"name\": \"<string>\",\n  \"is_index\": \"<string>\"\n}")

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

	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://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id}")
  .header("Content-Type", "application/json")
  .body("{\n  \"namespace\": \"<string>\",\n  \"handle\": \"<string>\",\n  \"value\": \"<string>\",\n  \"name\": \"<string>\",\n  \"is_index\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api.{tenant}.getomneo.com/api/v3/custom-fields/{model}/{id}")

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

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"namespace\": \"<string>\",\n  \"handle\": \"<string>\",\n  \"value\": \"<string>\",\n  \"name\": \"<string>\",\n  \"is_index\": \"<string>\"\n}"

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

{
  "data": {
    "name": "<string>",
    "handle": "<string>",
    "namespace": "<string>",
    "value": "<string>",
    "type": "<string>",
    "custom_fieldable_type": "<string>",
    "custom_fieldable": {
      "id": "<string>",
      "external_id": "<string>",
      "profile_id": "<string>",
      "meta": "<string>",
      "total": "<string>",
      "total_original": "<string>",
      "rounding": "<string>",
      "margin": "<string>",
      "is_void": "<string>",
      "transacted_at": "<string>",
      "timezone": "<string>",
      "payments": "<string>",
      "receipt_is_email": "<string>",
      "receipt_ref": "<string>",
      "linked_receipt_ref": "<string>",
      "claimed_at": "<string>",
      "receipt_email": "<string>",
      "currency_id": "<string>",
      "currency_rate": "<string>",
      "currency": "<string>",
      "type": "<string>",
      "status": "<string>",
      "order_number": "<string>",
      "order_id": "<string>",
      "external_order_id": "<string>",
      "created_at": "<string>",
      "updated_at": "<string>"
    },
    "created_at": "<string>",
    "updated_at": "<string>",
    "is_index": 123
  }
}

{
  "message": "<string>"
}

{
  "message": "<string>"
}

{
  "message": "<string>",
  "errors": {}
}

{
  "errors": [
    "<string>"
  ]
}