using RestSharp;


var options = new RestClientOptions("https://api.sandbox.{id}.gr4vy.app/gift-card-services");
var client = new RestClient(options);
var request = new RestRequest("");
request.AddHeader("Authorization", "Bearer <token>");
request.AddJsonBody("{\n  \"gift_card_service_definition_id\": \"qwikcilver-gift-card\",\n  \"display_name\": \"Qwikcilver UK\",\n  \"fields\": [\n    {\n      \"key\": \"private_key\",\n      \"value\": \"pk_26PHem9AhJZvU623DfE1x4sd\"\n    }\n  ]\n}", false);
var response = await client.PostAsync(request);

Console.WriteLine("{0}", response.Content);

package main

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

func main() {

	url := "https://api.sandbox.{id}.gr4vy.app/gift-card-services"

	payload := strings.NewReader("{\n  \"gift_card_service_definition_id\": \"qwikcilver-gift-card\",\n  \"display_name\": \"Qwikcilver UK\",\n  \"fields\": [\n    {\n      \"key\": \"private_key\",\n      \"value\": \"pk_26PHem9AhJZvU623DfE1x4sd\"\n    }\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://api.sandbox.{id}.gr4vy.app/gift-card-services")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"gift_card_service_definition_id\": \"qwikcilver-gift-card\",\n  \"display_name\": \"Qwikcilver UK\",\n  \"fields\": [\n    {\n      \"key\": \"private_key\",\n      \"value\": \"pk_26PHem9AhJZvU623DfE1x4sd\"\n    }\n  ]\n}")
  .asString();

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.sandbox.{id}.gr4vy.app/gift-card-services",
  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([
    'gift_card_service_definition_id' => 'qwikcilver-gift-card',
    'display_name' => 'Qwikcilver UK',
    'fields' => [
        [
                'key' => 'private_key',
                'value' => 'pk_26PHem9AhJZvU623DfE1x4sd'
        ]
    ]
  ]),
  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;
}

import requests

url = "https://api.sandbox.{id}.gr4vy.app/gift-card-services"

payload = {
    "gift_card_service_definition_id": "qwikcilver-gift-card",
    "display_name": "Qwikcilver UK",
    "fields": [
        {
            "key": "private_key",
            "value": "pk_26PHem9AhJZvU623DfE1x4sd"
        }
    ]
}
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({
    gift_card_service_definition_id: 'qwikcilver-gift-card',
    display_name: 'Qwikcilver UK',
    fields: [{key: 'private_key', value: 'pk_26PHem9AhJZvU623DfE1x4sd'}]
  })
};

fetch('https://api.sandbox.{id}.gr4vy.app/gift-card-services', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

curl --request POST \
  --url https://api.sandbox.{id}.gr4vy.app/gift-card-services \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "gift_card_service_definition_id": "qwikcilver-gift-card",
  "display_name": "Qwikcilver UK",
  "fields": [
    {
      "key": "private_key",
      "value": "pk_26PHem9AhJZvU623DfE1x4sd"
    }
  ]
}
'

{
  "type": "gift-card-service",
  "id": "6c020bf3-179b-4f4f-858d-84e39e196e0f",
  "merchant_account_id": "default",
  "gift_card_service_definition_id": "qwikcilver-gift-card",
  "display_name": "Qwikcilver UK",
  "active": true,
  "fields": [
    {
      "key": "secret_key",
      "value": "sk_test_26PHem9AhJZvU623DfE1x4sd"
    }
  ],
  "created_at": "2012-12-12T10:53:43+00:00",
  "updated_at": "2012-12-12T10:53:43+00:00"
}

{
  "type": "error",
  "code": "bad_request",
  "status": 400,
  "message": "Missing '****' field",
  "details": [
    {
      "location": "body",
      "type": "value_error.missing",
      "pointer": "/payment_method/number",
      "message": "field required"
    }
  ]
}

{
  "type": "error",
  "code": "unauthorized",
  "status": 401,
  "message": "No valid API authentication found",
  "details": []
}

{
  "type": "error",
  "code": "duplicate_record",
  "status": 409,
  "message": "A duplicate record exists with this external_identifier value",
  "details": []
}