construction/payloads - Cardano

Example code for the construction/payloads JSON-RPC method. Complete guide on how to use construction/payloads JSON-RPC in GetBlock Web3 documentation.

This endpoint builds an unsigned transaction and the payloads that must be signed, from the operations and metadata. It is an offline step that returns the material to sign.

Parameters

The request body is a JSON object with the following fields.

Field	Type	Required	Description
network_identifier	object	Yes	The network to construct for
operations	array	Yes	The operations describing the transaction
metadata	object	Yes	Metadata returned by the metadata endpoint

Request

cURL

curl --location --request POST 'https://go.getblock.io/<ACCESS-TOKEN>/construction/payloads' \
--header 'Content-Type: application/json' \
--data-raw '{
    "network_identifier": {
        "blockchain": "cardano",
        "network": "mainnet"
    },
    "operations": [
        {
            "operation_identifier": {
                "index": 0
            },
            "type": "output",
            "account": {
                "address": "addr1qxy2lpan99fcnhhyzr8w8qk4dqz4mp7g6b8h3r2v5c9d0e1f2g3h4j5k6l7m8n9p0q"
            },
            "amount": {
                "value": "9240398",
                "currency": {
                    "symbol": "ADA",
                    "decimals": 6
                }
            }
        }
    ],
    "metadata": {
        "ttl": "10454789"
    }
}'

JavaScript

example.js

const response = await fetch(
    'https://go.getblock.io/<ACCESS-TOKEN>/construction/payloads',
    {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({"network_identifier": {"blockchain": "cardano", "network": "mainnet"}, "operations": [{"operation_identifier": {"index": 0}, "type": "output", "account": {"address": "addr1qxy2lpan99fcnhhyzr8w8qk4dqz4mp7g6b8h3r2v5c9d0e1f2g3h4j5k6l7m8n9p0q"}, "amount": {"value": "9240398", "currency": {"symbol": "ADA", "decimals": 6}}}], "metadata": {"ttl": "10454789"}})
    }
);
console.log(await response.json());

Python

example.py

import requests

response = requests.post(
    'https://go.getblock.io/<ACCESS-TOKEN>/construction/payloads',
    headers={'Content-Type': 'application/json'},
    json={"network_identifier": {"blockchain": "cardano", "network": "mainnet"}, "operations": [{"operation_identifier": {"index": 0}, "type": "output", "account": {"address": "addr1qxy2lpan99fcnhhyzr8w8qk4dqz4mp7g6b8h3r2v5c9d0e1f2g3h4j5k6l7m8n9p0q"}, "amount": {"value": "9240398", "currency": {"symbol": "ADA", "decimals": 6}}}], "metadata": {"ttl": "10454789"}}
)

print(response.json())

Response

{
    "unsigned_transaction": "a400818258200e...unsigned-cbor...",
    "payloads": [
        {
            "account_identifier": {
                "address": "addr1qxy2lpan99fcnhhyzr8w8qk4dqz4mp7g6b8h3r2v5c9d0e1f2g3h4j5k6l7m8n9p0q"
            },
            "hex_bytes": "3e6f2d8c...signing-payload",
            "signature_type": "ed25519"
        }
    ]
}

Response Parameters

Field	Type	Description
unsigned_transaction	string	The unsigned transaction in CBOR hex
payloads	array	The payloads to sign, each with the account and bytes

Use Cases

• Transaction Building: Produce an unsigned transaction from operations

• Offline Signing: Return payloads to sign on an air-gapped device

• Multi-Signature: Enumerate the payloads each signer must sign

• Construction Flow: Advance the flow to the parse and combine steps

Error Handling

Error Code	Message	Description
1	Invalid request	A required construction field is missing or malformed
6	Transaction decode failed	The supplied transaction could not be decoded
14	Invalid signature	A supplied signature is malformed or does not match
5	Internal error	The node failed to process the construction step