Lesson 4: Cannot create a Contract Call in Ganache

[Pasonnn]

Deploy.py_____

from solcx import compile_standard, install_solc
import json
from web3 import Web3
import os
from dotenv import load_dotenv

load_dotenv()

install_solc("0.6.0")

from solcx import compile_standard

with open("./SimpleStorage.sol", "r") as file:
    simple_storage_file = file.read()

# Compile Our Solidity

compiled_sol = compile_standard(
    {
        "language": "Solidity",
        "sources": {"SimpleStorage.sol": {"content": simple_storage_file}},
        "settings": {
            "outputSelection": {
                "*": {"*": ["abi", "metadata", "evm.bytecode", "evm.sourceMap"]}
            }
        },
    },
    solc_version="0.6.0",
)

with open("compiled_code.json", "w") as file:
    json.dump(compiled_sol, file)

# get bytecode
bytecode = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["evm"][
    "bytecode"
]["object"]

# get abi
abi = compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["abi"]

# for connecting to ganache
w3 = Web3(Web3.HTTPProvider("HTTP://127.0.0.1:7545"))
chain_id = 1337
version = 5777
my_address = "0x4434398D50Bf378c47C054B8d91E5862FfDad20C"
private_key = os.getenv("PRIVATE_KEY2")

# Create the contract in Python
SimpleStorage = w3.eth.contract(abi=abi, bytecode=bytecode)

# Get the latest transaction
nonce = w3.eth.getTransactionCount(my_address)
# 1. Build a transaction
# 2. Sign a transaction
# 3. Send a transaction
transaction = SimpleStorage.constructor().buildTransaction(
    {
        "chainId": chain_id,
        "gasPrice": w3.eth.gas_price,
        "from": my_address,
        "nonce": nonce,
    }
)

signed_txn = w3.eth.account.sign_transaction(transaction, private_key=private_key)

# Send this signed transaction
print("Deploying contact...")
tx_hash = w3.eth.send_raw_transaction(signed_txn.rawTransaction)
tx_receipt = w3.eth.wait_for_transaction_receipt(tx_hash)
print("Deployed!")
# Working with Contract, you need:
# Contract ABI
# Contract Address
simple_storage = w3.eth.contract(address=tx_receipt.contractAddress, abi=abi)
# Call -> Simulate making the call and getting a return value
# Transact -> Actually make a state change

# Initial value of favorite number
print(simple_storage.functions.retrieve().call())
print("Updating Contract...")
store_transaction = simple_storage.functions.store(15).buildTransaction(
    {
        "chainId": chain_id,
        "gasPrice": w3.eth.gas_price,
        "from": my_address,
        "nonce": nonce + 1,
    }
)
signed_store_txn = w3.eth.account.sign_transaction(
    store_transaction, private_key=private_key
)
send_store_tx = w3.eth.send_raw_transaction(signed_store_txn.rawTransaction)
tx_receipt = w3.eth.wait_for_transaction_receipt(send_store_tx)
print("Updated!")
print(simple_storage.functions.retrieve().call())

.env_____
export PRIVATE_KEY3=4d2xxxxx
export SOME_OTHER_VAR=7

_________________________________
Terminal:
INFO: Could not find files for the given pattern(s).
Traceback (most recent call last):
  File "C:\Users\jimmy\demos\web3_py_simple_storage\Deploy.py", line 66, in <module>
    signed_txn = w3.eth.account.sign_transaction(transaction, private_key=private_key)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_account\account.py", line 728, in sign_transaction
    account = self.from_key(private_key)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_account\account.py", line 250, in from_key
    key = self._parsePrivateKey(private_key)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\eth_account\account.py", line 775, in _parsePrivateKey
    return self._keys.PrivateKey(HexBytes(key))
  File "C:\Users\jimmy\anaconda3\lib\site-packages\hexbytes\main.py", line 38, in __new__
    bytesval = to_bytes(val)
  File "C:\Users\jimmy\anaconda3\lib\site-packages\hexbytes\_utils.py", line 32, in to_bytes
    raise TypeError(f"Cannot convert {val!r} of type {type(val)} to bytes")
TypeError: Cannot convert None of type <class 'NoneType'> to bytes

[cromewar]

Hello @Pasonnn
First of all please do not share your private keys here, I edited the post and remove it. Remember is a security risk.

Now, based on the error message it seems you are not getting correctly that private key from your env, so please be sure you are using load_dotenv and actually loading the .env key before using on this line:

signed_txn = w3.eth.account.sign_transaction(transaction, private_key=private_key)

My guess is that you should have a wrong name on the env file.. like not setting up a dot .env or creating it no the incorrect folder.
Please let us know if this make sense for you.