- web3.py 4.7.2
- API Key from infura.io
- Source account and its private key
infuraApi = 'API'
account = 'SRC ACCOUNT'
key = 'PRIVATE KEY'
pragma solidity ^0.4.22;
contract HelloWorld {
string public message;
constructor() public {
message = "Hello, World!";
}
function setMessage(string text) public payable{
require(msg.value >= 0.01 ether);
message = text;
}
}
A simple "Hello, World" program that allows to change its message which call be called with ".message().call()".
from utils import contractSource
from solc import compile_source
contractCompiled = compile_source(contractSource("HelloWorld"))
contractInterface = contractCompiled['<stdin>:HelloWorld']Note: contractSource is a function defined in src/utils.py and its read the HelloWorld.sol file's content.
helloWorld = w3.eth.contract(abi=contractInterface['abi'], bytecode=contractInterface['bin'])contractInterface returns a dict with the Contracts inside of .sol file. In this cenario there is only one "HelloWorld".
txParams = {
'gas': 2000000,
'gasPrice': w3.eth.gasPrice,
'nonce': w3.eth.getTransactionCount(account),
'chainId': 4, # Rinkeby Test Network
'from': account
}tx = helloWorld.constructor().buildTransaction(txParams)signedTx = w3.eth.account.signTransaction(tx, key)txReceipt = w3.eth.sendRawTransaction(signedTx.rawTransaction)If sendRawTransaction is successful it returns a hash: 0xea1bb31684fa63f13008f11c3ddbfed444835e9e8d0a279ff806e52b8e527b95
which can be used to get the transaction's detail. Check in rinkeby.etherscan.io.
receipt = w3.eth.waitForTransactionReceipt(txReceipt)The function above returns the following dictionary:
AttributeDict({'blockHash': HexBytes('0x68dc9bc28a5e8fa2f5ff6325f13e8bd2f0560ca543bf011d71f9e1ed00f86e5c'),
'blockNumber': 3224432,
'contractAddress': '0x327fE98DaF48836e982396cF3cf4Bf468Ca11Ea8',
'cumulativeGasUsed': 5460633,
'from': '0xf31a44312c4cc8cfd207e5baa654f5597e461552',
'gasUsed': 282543,
'logs': [],
'logsBloom': HexBytes('a lot of zeros'),
'status': 1,
'to': None,
'transactionHash': HexBytes('0xea1bb31684fa63f13008f11c3ddbfed444835e9e8d0a279ff806e52b8e527b95'),
'transactionIndex': 9})The 'contractAddress' field will be used to interact with the deployed contract in the next section.
helloWorldInstance = w3.eth.contract(
receipt.contractAddress,
abi=contractInterface['abi'],
)helloWorldInstance.functions.message().call() # returns "Hello, World!"
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