PyOST

Python SDK for the IOST blockchain, wrap the RPC API to easily create and send transactions, manage accounts, publish and execute smart contracts, etc.

Installation

Install the library and its dependencies. Needs at least Python 3.7.

$ pip install pyost

Examples

Blockchain Information

Connect to the blockchain:

from pyost.iost import IOST
iost = IOST('localhost:30002')

Get information about the blockchain:

print(iost.get_node_info())
print(iost.get_chain_info())
print(iost.get_ram_info())
print(iost.get_gas_ratio())

Get information about a block:

# By block number.
block0 = iost.get_block_by_num(0)
print(block0)

# By block hash, complete=True will retrieve the full list of Transactions.
print(iost.get_block_by_hash(block0.hash, complete=True))

Account Creation

Load an account from a base58 secret key:

from base58 import b58decode
from pyost.account import Account
from pyost.algorithm import Ed25519
from pyost.signature import KeyPair
acc_seckey = b58decode(b'<your base58 private key>')
acc_kp = KeyPair(Ed25519, acc_seckey)
acc = Account('<account_name>')
acc.add_key_pair(acc_kp, 'active')
acc.add_key_pair(acc_kp, 'owner')

Get account information and token balances:

print(iost.get_account_info(acc.name))
print(iost.get_token_balance(acc.name))
print(iost.get_token721_balance(acc.name, 'token_name'))

Create a new account, first we need to generate a pair of public and private keys:

acc2_kp = KeyPair(Ed25519)
# WARNING Do not forget to store the new account secret key:
from base58 import b58encode
print(b58encode(acc2_kp.seckey))

acc2 = Account('<new_account_name>')
acc2.add_key_pair(acc2_kp, 'active')
acc2.add_key_pair(acc2_kp, 'owner')

Then we must use an existing account to pledge coins for this new account:

from pyost.transaction import TransactionError

tx = iost.create_new_account_tx(acc2.name, acc.name,
                                b58encode(acc2_kp.pubkey),
                                b58encode(acc2_kp.pubkey), 0, 100.0, 100.0)
tx.gas_limit = 1000000.0
acc.sign_publish(tx)

try:
    receipt = iost.send_and_wait_tx(tx)
except (TransactionError, TimeoutError):
    pass

There is a shorter version for the previous 2 blocks of code:

# Need to set the first account as the default publisher to automatically sign Transactions:
iost.publisher = acc

try:
    acc2 = iost.new_account('<new_account_name>', acc.name, 0, 100.0, 100.0, Ed25519)
except (TransactionError, TimeoutError):
    pass

# WARNING Do not forget to store the new account secret key:
print(b58encode(acc2.get_key_pair('active').seckey))

Calling an ABI function

Example to buy RAM for own account:

ram_amount = 1024
tx = iost.create_call_tx('ram.iost', 'buy', acc.name, acc.name, ram_amount)
acc.sign_publish(tx)

try:
    receipt = iost.send_and_wait_tx(tx)
except (TransactionError, TimeoutError):
    pass

Token Transfer

token = 'iost'
from_name = acc.name
to_name = acc2.name
amount = 10000

Create a transfer Transaction, there are multiple way. Manually:

from pyost.transaction import Transaction
tx = Transaction(gas_limit=100000.0, gas_ratio=1.0, expiration=90, delay=0)
tx.add_amount_limit('*', 'unlimited')
tx.add_amount_limit('iost', str(amount))
tx.add_action('token.iost', 'transfer', token, from_name, to_name, str(amount), '')

By using the Transaction creation helper function:

tx = iost.create_tx()
tx.add_action('token.iost', 'transfer', token, from_name, to_name, str(amount), '')
tx.add_amount_limit('iost', str(amount))

By using the call creation helper function:

tx = iost.create_call_tx('token.iost', 'transfer', token, from_name, to_name, str(amount), '')
tx.add_amount_limit('iost', str(amount))

By using the transfer creation helper function:

tx = iost.create_transfer_tx('iost', from_name, to_name, amount)

You can now sign this Transaction with multiple signers (this is not mandatory for transfer, just to illustrate multi-sig):

tx.add_signer(acc2.name, 'active')
acc2.sign(tx, 'active')

You must sign the Transaction with one publisher (if no signers was added in the previous step, the publisher must be the same as the from_name account):

acc.sign_publish(tx)

And finally send the Transaction and wait for it to be processed:

try:
    receipt = iost.send_and_wait_tx(tx)
    # Alternatively:
    # receipt = iost.wait_tx(iost.send_tx(tx), verbose=True)
except (TransactionError, TimeoutError):
    pass

There is a shorter version for all code in this section:

iost.publisher = acc

try:
    receipt = iost.transfer('iost', from_name, to_name, amount)
except (TransactionError, TimeoutError):
    pass

Publishing and Calling Smart Contract

Load the smart contract code and ABI files:

with open(js_file, 'r') as f:
    code = f.read()
with open(js_abi_file, 'r') as f:
    abi_file = json.load(f)

from pyost.contract import Contract
contract = Contract(code=code).from_json(abi_file)

Publish it as follow and save the returned contract id:

try:
    receipt = iost.publish(contract)
except (TransactionError, TimeoutError):
    pass
contract_id = json.loads(receipt.returns[0])[0]

Call the contract's ABI:

txr = iost.call(contract_id, '<func_name>', '<args1>', '<args2>')
res = json.loads(txr.returns[0])[0]
print(f'Response: {res}')

Upate the contract's code:

txr = iost.call('system.iost', 'updateCode', new_contract.to_json(), '')
print(txr.status_code.name)

Token Creation

Create a new token:

token_sym = '<token_name>'
token_amount = 21000000
tx = iost.create_call_tx('token.iost', 'create', token_sym, acc.name, token_amount,
                         {"fullName": "bit coin", "decimal": 9})
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)

Issue tokens:

issue_amount = 99.1
tx = iost.create_call_tx('token.iost', 'issue', token_sym, acc.name, str(issue_amount))
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)

print(iost.get_balance(acc.name, token_sym))

Transfer tokens:

transfer_amount = 55.000000001
print(iost.get_balance(acc.name, token_sym))
print(iost.get_balance(acc2.name, token_sym))

tx = iost.create_transfer_tx(token_sym, acc.name, acc2.name, transfer_amount)
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)

print(iost.get_balance(acc.name, token_sym))
print(iost.get_balance(acc2.name, token_sym))

Transfer freeze:

transfer_amount = 5
tx = iost.create_call_tx('token.iost', 'transferFreeze',
                         token_sym, acc.name, acc2.name, str(transfer_amount),
                         int((time.time() + 5000) * 1e6), '')
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)
print(iost.get_token_balance(acc2.name, token_sym).frozen_balances[0])

Balance of:

tx = iost.create_call_tx('token.iost', 'balanceOf',
                         token_sym, acc.name)
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)
print(iost.get_balance(acc2.name, token_sym))

Get token supply:

tx = iost.create_call_tx('token.iost', 'supply', token_sym)
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)
print(txr.returns[0])

Destroy tokens:

destroy_amount = 10
tx = iost.create_call_tx('token.iost', 'destroy',
                         token_sym, acc.name, str(destroy_amount))
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)

Total supply:

tx = iost.create_call_tx('token.iost', 'totalSupply', token_sym)
acc.sign_publish(tx)
txr = iost.send_and_wait_tx(tx)
print(txr.returns[0])