Lesson 4: Error when I apply Environment Variables in Visual Studio

[HalaAura]

Hello!
When I run: python deploy.py after adding os.getenv("PRIVATE_KEY") to the code it gives me type error I couldn't know where is the problem :( what did I miss?

Here's the code:

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

solcx.install_solc("0.8.7")  # or whatever version we want
with open("SimpleStorage.sol", "r") as file:
    simple_storage_file = file.read()
    print("Installing...")
    install_solc("0.6.0")

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",
)

# print(compiled_sol)
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 = json.loads(
    compiled_sol["contracts"]["SimpleStorage.sol"]["SimpleStorage"]["metadata"]
)["output"]["abi"]


w3 = Web3(Web3.HTTPProvider("HTTP://127.0.0.1:7545"))
chain_id = 1337
my_address = "0xaADe4fEB069c55E1394Db2E5467Ff147D0fbC7Eb"
private_key = os.getenv("PRIVATE_KEY")
print(private_key)


SimpleStorage = w3.eth.contract(abi=abi, bytecode=bytecode)
# Get the latest transaction
nonce = w3.eth.getTransactionCount(my_address)
print(nonce)

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)

The error:

NFO: Could not find files for the given pattern(s).
Installing...
None
0
Traceback (most recent call last):
  File "C:\Users\user\web3.py\deploy.py", line 61, in <module>
    signed_txn = w3.eth.account.sign_transaction(transaction, private_key=private_key)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_account\account.py", line 727, in sign_transaction
    account = self.from_key(private_key)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_account\account.py", line 250, in from_key
    key = self._parsePrivateKey(private_key)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_utils\decorators.py", line 18, in _wrapper
    return self.method(obj, *args, **kwargs)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\eth_account\account.py", line 774, in _parsePrivateKey
    return self._keys.PrivateKey(HexBytes(key))
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\hexbytes\main.py", line 23, in __new__
    bytesval = to_bytes(val)
  File "C:\Users\user\AppData\Local\Programs\Python\Python310\lib\site-packages\hexbytes\_utils.py", line 30, 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
PS C:\Users\user\web3.py> 

[cromewar]

Hello @HalaAura you have a mismatch on the solcx versions solcx.install_solc("0.8.7") # or whatever version we want you don't need this line. Also regarding to the env variables, as you are on windows you'll probably would have to add them to your path through windows advanced configuration, otherwise vscode might not recognize it.

Best regards, Cromewar.

[HalaAura]

Thank you so much! I continued the video and I created .env file. Now everything seems fine :)

[cromewar]

I'm glad you solved the problem.