Basic use of SmartBCH with Python, Web3Py

SmartBCH becoming is becoming more popular with time, It brings the best of Ethereum world to BCH. I wanted to explore it and help others too so I created this short introduction to use smartBCH for Python developers.

First you should install web3 :

pip3 install web3

Let us start a Python interpreter and import Web3:

>>> from web3 import Web3

Then we should use a provider, for a quick start you will depend on an external service that connects us to the network

>>> w3 = Web3(Web3.HTTPProvider('https://smartbch.fountainhead.cash/mainnet'))

We have used here the smartBCH node from fountainhead.cash here is a list of provider that we can use:

• https://smartbch.fountainhead.cash/mainnet

• wss://smartbch-wss.greyh.at

• https://global.uat.cash

• https://rpc.uatvo.com

• http://35.220.203.194:8545 (testnet) ℹ️

• https://moeing.tech:9545 (testnet) ℹ️

If you use the one with Websocket instead of http you will have to change the provider method to be Websocket like this:

w3 = Web3(Web3.WebsocketProvider('wss://smartbch-wss.greyh.at'))

Testing connection

Let us test connection, we should get True if the node is up and ready:

>>> w3.isConnected()
True

Lest us start querying for some useful data, Let us query for the latest block :

>>> w3.eth.get_block('latest')
AttributeDict({'difficulty': 0, 'extraData': HexBytes('0x'), 'gasLimit': 1000000000, 'gasUsed': 0, 'hash': HexBytes('0xcfa93b9979df7ea7658940eb319a22a208947f43c4983a83c5d7bc7934d88d5c'), 'logsBloom': HexBytes('0x00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'), 'miner': '0x930C23CE7536B0ede6AfE7754134d4011217D6AA', 'mixHash': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'nonce': HexBytes('0x0000000000000000'), 'number': 665462, 'parentHash': HexBytes('0xbe439275cbc6588651ea43c4b58c3372c3a5a7ee18b639a9f0390f58d05adceb'), 'receiptsRoot': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'sha3Uncles': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'size': 557, 'stateRoot': HexBytes('0x38bbd2b0bfb71e273080fee38aaf84edd25bcf04e30a874f781a10252a93a521'), 'timestamp': 1631452685, 'totalDifficulty': 0, 'transactions': [], 'transactionsRoot': HexBytes('0x0000000000000000000000000000000000000000000000000000000000000000'), 'uncles': []})

To just get the number of latest block:

>>> w3.eth.block_number
665466

To get the balance of an account/address:

>>> w3.eth.get_balance('0x54E4F23a819F0DDe10344F5BD06b57906a752934')
393343977270000000

Balances are shown in a unit called Wei by default, to convert to BCH use:

>>> balance = w3.eth.get_balance('0x54E4F23a819F0DDe10344F5BD06b57906a752934')
>>> w3.fromWei(balance, 'ether')
Decimal('0.39117037731')

To convert from BCH to Wei:

>>> w3.toWei(Decimal('0.000000005'), 'ether')
5000000000

To get a transaction detail:

>>> w3.eth.get_transaction('0xaac856e36d6ccae43bc07c1e078e4c29efb14efc8f0d795c63632557c1bb1642')
AttributeDict({'blockHash': HexBytes('0x649d3f7eb7fbe805edb6ad7d63aceb60041c4ede1ca5f1e31b4bab6da1ad0442'), 'blockNumber': 631598, 'from': '0x579564809ACDA82232b91f2931a0876f97669df6', 'gas': 208096, 'gasPrice': 1050000000, 'hash': HexBytes('0xaac856e36d6ccae43bc07c1e078e4c29efb14efc8f0d795c63632557c1bb1642'), 'input': '0xe2bbb158000000000000000000000000000000000000000000000000000000000000000100000000000000000000000000000000000000000000000f3b4741d5bbf42c20', 'nonce': 32, 'to': '0xDEa721EFe7cBC0fCAb7C8d65c598b21B6373A2b6', 'transactionIndex': 1, 'value': 0, 'v': None, 'r': None, 's': None})

To lookup transaction receipt:

>>> w3.eth.get_transaction_receipt('0xaac856e36d6ccae43bc07c1e078e4c29efb14efc8f0d795c63632557c1bb1642') 

Contracts

I don't have good understanding of how contracts work on Ethereum but still we can query them and get some useful information.

To start dealing with contracts we need two pieces of information:

1. Contract address

2. ABI (Application Binary Interface)

Contract Address

Normally you can find the contract on the explorer and it seems it serve similar purpose to token id for SLP token.

You can look it from here:

https://www.smartscan.cash/address/0x481De06DCA0198844faA36FCa04Db364e5c2f86C

Address should be in Checksum format (few letters should be capitals), if you got the address in non-checksum format you can use this to convert it:

>>> w3.toChecksumAddress('0x481de06dca0198844faa36fca04db364e5c2f86c')
'0x481De06DCA0198844faA36FCa04Db364e5c2f86C'

ABI

@b_s_z in smartBCH community group on Telegram provided me with the ABI for the Maze token, you can get it from this gitlab snippet:

https://gitlab.com/-/snippets/2174502

In Etherscan you can see an Ethereum Token API like this one for Tether

Dealing with contracts

After getting the address and ABI we assign them, I'll not post the full ABI here as it's a bit long. Just copy it from snippet, you may want to minify so it fit in one line.

>>> address = '0x481De06DCA0198844faA36FCa04Db364e5c2f86C'
>>> abi = '[{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"payable":false, OMITTED

Then we create an instance for the contract and check for the address:

>>> contract = w3.eth.contract(address=address, abi=abi)
>>> contract.address
'0x481De06DCA0198844faA36FCa04Db364e5c2f86C'

Get token symbol:

>>> contract.functions.symbol().call()
'MAZE'

We can ask for total supply:

>>> contract.functions.totalSupply().call()
21000000000000

Number of decimals:

>>> contract.functions.decimals().call()
6

Get Token balance on account:

>>> bob = '0x481De06DCA0198844faA36FCa04Db364e5c2f86C'
>>> raw_balance = contract.functions.balanceOf(bob).call()
>>> raw_balance
1000000000

You can find much more examples from Web3.py example page, All what I've to do is to set the provider to SmartBCH provider. You need also to make sure that unites are correct because apparently it uses Ethereum definition like wei and ether.

Resources

• Web3py quickstart

• Web3py examples

• How to get an ABI, seems extractable from contract.

• Maze contract, Maze ABI

• SmartBCH explorer

• SmartBCH community on Telegram

• SmartBCH official website

In this article I've just explained few very basic uses. Hopefully in the feature I'll have time to explore EVM more. It's attractive and very useful.