FetchAssetMeta

FetchAssetMeta allows a caller to fetch the reveal meta data for an asset either by the asset ID for that asset, or a meta hash.

Source: taprootassets.proto

gRPC

rpc FetchAssetMeta (FetchAssetMetaRequest) returns (AssetMeta);

REST

HTTP Method	Path
GET	/v1/taproot-assets/assets/meta/asset-id/{asset_id_str}

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('taprootassets.proto', loaderOptions);
const taprpc = grpc.loadPackageDefinition(packageDefinition).taprpc;
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 taprpc.TaprootAssets(GRPC_HOST, creds);
let request = {
  asset_id: <bytes>,
  meta_hash: <bytes>,
  asset_id_str: <string>,
  meta_hash_str: <string>,
};
client.fetchAssetMeta(request, function(err, response) {
  console.log(response);
});
// Console output:
//  {
//    "data": <bytes>,
//    "type": <AssetMetaType>,
//    "meta_hash": <bytes>,
//  }

Python

import codecs, grpc, os
# Generate the following 2 modules by compiling the taprootassets.proto with the grpcio-tools.
# See https://github.com/lightningnetwork/lnd/blob/master/docs/grpc/python.md for instructions.
import taprootassets_pb2 as taprpc, taprootassets_pb2_grpc as taprootassetsstub

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 = taprootassetsstub.TaprootAssetsStub(channel)
request = taprpc.FetchAssetMetaRequest(
  asset_id=<bytes>,
  meta_hash=<bytes>,
  asset_id_str=<string>,
  meta_hash_str=<string>,
)
response = stub.FetchAssetMeta(request)
print(response)
# {
#    "data": <bytes>,
#    "type": <AssetMetaType>,
#    "meta_hash": <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 options = {
  url: `https://${REST_HOST}/v1/taproot-assets/assets/meta/asset-id/{asset_id_str}`,
  // Work-around for self-signed certificates.
  rejectUnauthorized: false,
  json: true,
  headers: {
    'Grpc-Metadata-macaroon': fs.readFileSync(MACAROON_PATH).toString('hex'),
  },
}
request.get(options, function(error, response, body) {
  console.log(body);
});
// Console output:
//  {
//    "data": <string>, // <bytes> 
//    "type": <string>, // <AssetMetaType> 
//    "meta_hash": <string>, // <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/assets/meta/asset-id/{asset_id_str}'
macaroon = codecs.encode(open(MACAROON_PATH, 'rb').read(), 'hex')
headers = {'Grpc-Metadata-macaroon': macaroon}
r = requests.get(url, headers=headers, verify=TLS_PATH)
print(r.json())
# {
#    "data": <bytes>,
#    "type": <AssetMetaType>,
#    "meta_hash": <bytes>,
# }

Shell

$ tapcli assets meta --help

NAME:
   tapcli assets meta - fetch asset meta

USAGE:
   tapcli assets meta [command options] [arguments...]

DESCRIPTION:
   fetch the meta bytes for an asset based on the asset_id or meta_hash

OPTIONS:
   --asset_id value    asset_id to fetch meta for
   --asset_meta value  meta_hash to fetch meta for
   

Messages

taprpc.FetchAssetMetaRequest

Source: taprootassets.proto

Field	gRPC Type	REST Type	REST Placement
asset_id The asset ID of the asset to fetch the meta for.	bytes	string	query
meta_hash The 32-byte meta hash of the asset meta.	bytes	string	query
asset_id_str The hex encoded asset ID of the asset to fetch the meta for.	string	string	path
meta_hash_str The hex encoded meta hash of the asset meta.	string	string	query

taprpc.AssetMeta

Source: taprootassets.proto

Field	gRPC Type	REST Type
data The raw data of the asset meta data. Based on the type below, this may be structured data such as a text file or PDF. The size of the data is limited to 1MiB.	bytes	string
type The type of the asset meta data.	AssetMetaType	string
meta_hash The hash of the meta. This is the hash of the TLV serialization of the meta itself.	bytes	string

Enums

taprpc.AssetMetaType

Name	Number
META_TYPE_OPAQUE Opaque is used for asset meta blobs that have no true structure and instead should be interpreted as opaque blobs.	0
META_TYPE_JSON JSON is used for asset meta blobs that are to be interpreted as valid JSON strings.	1