curl --request PATCH \
  --url https://merchant.zahlo.eu/api/v1/invoices/{id} \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "customerId": "cus_demo_1001",
  "amountDue": {
    "amountMinor": 1900,
    "currency": "EUR"
  }
}
'

import requests

url = "https://merchant.zahlo.eu/api/v1/invoices/{id}"

payload = {
    "customerId": "cus_demo_1001",
    "amountDue": {
        "amountMinor": 1900,
        "currency": "EUR"
    }
}
headers = {
    "x-api-key": "<api-key>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'PATCH',
  headers: {'x-api-key': '<api-key>', 'Content-Type': 'application/json'},
  body: JSON.stringify({customerId: 'cus_demo_1001', amountDue: {amountMinor: 1900, currency: 'EUR'}})
};

fetch('https://merchant.zahlo.eu/api/v1/invoices/{id}', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "id": "inv_demo_1001",
  "customerId": "cus_demo_1001",
  "status": "open",
  "amountDue": {
    "amountMinor": 1900,
    "currency": "EUR"
  }
}

{
  "error": "invalid_request",
  "message": "amountMinor must be positive",
  "requestId": "req_demo_1001"
}

{
  "error": "invalid_request",
  "message": "amountMinor must be positive",
  "requestId": "req_demo_1001"
}

{
  "error": "invalid_request",
  "message": "amountMinor must be positive",
  "requestId": "req_demo_1001"
}

{
  "error": "invalid_request",
  "message": "amountMinor must be positive",
  "requestId": "req_demo_1001"
}