FundVirtualPsbt

FundVirtualPsbt selects inputs from the available asset commitments to fund a virtual transaction matching the template.

Source: assetwalletrpc/assetwallet.proto

gRPC

rpc FundVirtualPsbt (FundVirtualPsbtRequest) returns (FundVirtualPsbtResponse);

REST

HTTP Method	Path
POST	/v1/taproot-assets/wallet/virtual-psbt/fund

Code Samples

gRPC

Javascript

const fs = require('fs');
const grpc = require('@grpc/grpc-js');
const protoLoader = require('@grpc/proto-loader');

const GRPC_HOST = 'localhost:10029'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
const TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

const loaderOptions = {
  keepCase: true,
  longs: String,
  enums: String,
  defaults: true,
  oneofs: true,
};
const packageDefinition = protoLoader.loadSync('assetwalletrpc/assetwallet.proto', loaderOptions);
const assetwalletrpc = grpc.loadPackageDefinition(packageDefinition).assetwalletrpc;
process.env.GRPC_SSL_CIPHER_SUITES = 'HIGH+ECDSA';
const tlsCert = fs.readFileSync(TLS_PATH);
const sslCreds = grpc.credentials.createSsl(tlsCert);
const macaroon = fs.readFileSync(MACAROON_PATH).toString('hex');
const macaroonCreds = grpc.credentials.createFromMetadataGenerator(function(args, callback) {
  let metadata = new grpc.Metadata();
  metadata.add('macaroon', macaroon);
  callback(null, metadata);
});
let creds = grpc.credentials.combineChannelCredentials(sslCreds, macaroonCreds);
let client = new assetwalletrpc.AssetWallet(GRPC_HOST, creds);
let request = {
  psbt: <bytes>,
  raw: <TxTemplate>,
  coin_select_type: <CoinSelectType>,
};
client.fundVirtualPsbt(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "funded_psbt": <bytes>,
//    "change_output_index": <int32>,
//    "passive_asset_psbts": <bytes>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the assetwalletrpc/assetwallet.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import assetwallet_pb2 as assetwalletrpc, assetwallet_pb2_grpc as assetwalletstub

GRPC_HOST = 'localhost:10029'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

# create macaroon credentials
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
def metadata_callback(context, callback):
  callback([('macaroon', macaroon)], None)
auth_creds = grpc.metadata_call_credentials(metadata_callback)
# create SSL credentials
os.environ['GRPC_SSL_CIPHER_SUITES'] = 'HIGH+ECDSA'
cert = open(TLS_PATH, 'rb').read()
ssl_creds = grpc.ssl_channel_credentials(cert)
# combine macaroon and SSL credentials
combined_creds = grpc.composite_channel_credentials(ssl_creds, auth_creds)
# make the request
channel = grpc.secure_channel(GRPC_HOST, combined_creds)
stub = assetwalletstub.AssetWalletStub(channel)
request = assetwalletrpc.FundVirtualPsbtRequest(
  psbt=<bytes>,
  raw=<TxTemplate>,
  coin_select_type=<CoinSelectType>,
)
response = stub.FundVirtualPsbt(request)
print(response)
# {
#    "funded_psbt": <bytes>,
#    "change_output_index": <int32>,
#    "passive_asset_psbts": <bytes>,
# }

REST

Javascript

const fs = require('fs');
const request = require('request');

const REST_HOST = 'localhost:8089'
const MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'

let requestBody = {
  psbt: <string>, // <bytes> (base64 encoded)
  raw: <object>, // <TxTemplate> 
  coin_select_type: <string>, // <CoinSelectType> 
};
let options = {
  url: `https://${REST_HOST}/v1/taproot-assets/wallet/virtual-psbt/fund`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
  form: JSON.stringify(requestBody),
}
request.post(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "funded_psbt": <string>, // <bytes> 
//    "change_output_index": <integer>, // <int32> 
//    "passive_asset_psbts": <array>, // <bytes> 
//  }

Python

import base64, codecs, json, requests

REST_HOST = 'localhost:8089'
MACAROON_PATH = 'TAPROOT-ASSETS_DIR/regtest/taproot-assets.macaroon'
TLS_PATH = 'TAPROOT-ASSETS_DIR/tls.cert'

url = f'https://{REST_HOST}/v1/taproot-assets/wallet/virtual-psbt/fund'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
data = {
  'psbt': base64.b64encode(<bytes>),
  'raw': <TxTemplate>,
  'coin_select_type': <CoinSelectType>,
}
r = requests.post(url, headers=headers, data=json.dumps(data), verify=TLS_PATH)
print(r.json())
# {
#    "funded_psbt": <bytes>,
#    "change_output_index": <int32>,
#    "passive_asset_psbts": <bytes>,
# }

Shell

# There is no CLI command for this RPC

Messages

assetwalletrpc.FundVirtualPsbtRequest

Source: assetwalletrpc/assetwallet.proto

Field	gRPC Type	REST Type	REST Placement
psbt Use an existing PSBT packet as the template for the funded PSBT.	bytes	string	body
raw Use the asset outputs and optional asset inputs from this raw template.	TxTemplate	object	body
coin_select_type Specify the type of coins that should be selected. Defaults to allowing both script trees and BIP-086 compliant inputs.	CoinSelectType	string	body

assetwalletrpc.FundVirtualPsbtResponse

Source: assetwalletrpc/assetwallet.proto

Field	gRPC Type	REST Type
funded_psbt The funded but not yet signed virtual PSBT packet.	bytes	string
change_output_index The index of the added change output or -1 if no change was left over.	int32	integer
passive_asset_psbts The list of passive virtual transactions that are anchored in the same BTC level anchor transaction inputs as the funded "active" asset above. These assets can be ignored when using the AnchorVirtualPsbts RPC, since they are retrieved, signed and committed automatically in that method. But the passive assets have to be included in the CommitVirtualPsbts RPC which is used when custom BTC level anchor transactions are created. The main difference to the "active" asset above is that the passive assets will not get their own entry in the transfer table of the database, since they are just carried along and not directly affected by the direct user action.	bytes[]	array

Nested Messages

assetwalletrpc.PrevId

Field	gRPC Type	REST Type
outpoint The bitcoin anchor output on chain that contains the input asset.	OutPoint	object
id The asset ID of the previous asset tree.	bytes	string
script_key The tweaked Taproot output key committing to the possible spending conditions of the asset.	bytes	string

assetwalletrpc.TxTemplate

Field	gRPC Type	REST Type
inputs An optional list of inputs to use. Every input must be an asset UTXO known to the wallet. The sum of all inputs must be greater than or equal to the sum of all outputs. If no inputs are specified, asset coin selection will be performed instead and inputs of sufficient value will be added to the resulting PSBT.	PrevId[]	array
recipients A map of all Taproot Asset addresses mapped to the anchor transaction's output index that should be sent to.	RecipientsEntry[]	object

assetwalletrpc.TxTemplate.RecipientsEntry

Field	gRPC Type	REST Type
key	string	unknown
value	uint64	unknown

taprpc.OutPoint

Field	gRPC Type	REST Type
txid Raw bytes representing the transaction id.	bytes	string
output_index The index of the output on the transaction.	uint32	integer

Enums

assetwalletrpc.CoinSelectType

Name	Number
COIN_SELECT_DEFAULT Use the default coin selection type, which currently allows script keys and key spend paths.	0
COIN_SELECT_BIP86_ONLY Explicitly only select inputs that are known to be BIP-086 compliant (have a key-spend path only and no script tree).	1
COIN_SELECT_SCRIPT_TREES_ALLOWED Allow the selection of inputs that have a script tree spend path as well as a key spend path.	2