Transaction from metamask using web3 in python

How to perform transaction from ethereum wallet on metamask

Steps to be followed:

1. First install and import web3 in python:

         from web3 import Web3

2. Now create connection with your network using web3

   w = Web3(Web3.HTTPProvider('https://ropsten.infura.io/v3/<API_TOKEN>'))

    

3. Now create nonce for you payment (Note: Nonce is a unique whole number which can be used only once)

   nonce = w.eth.getTransactionCount(account)

    

4. Now we will verify account using checksum

   addr_bytes = eth_utils.to_bytes(hexstr=account_2)

   checksum_encoded = checksum_encode(addr_bytes)

# Checksum (checksum_encode()) function

def checksum_encode(addr): 

    hex_addr = addr.hex()

    checksummed_buffer = ""

    # Treat the hex address as ascii/utf-8 for keccak256 hashing

    hashed_address = eth_utils.keccak(text=hex_addr).hex()

    # Iterate over each character in the hex address

    for nibble_index, character in enumerate(hex_addr):

        if character in "0123456789":

            # We can't upper-case the decimal digits

            checksummed_buffer += character

        elif character in "abcdef":

            # Check if the corresponding hex digit (nibble) in the hash is 8 or higher

            hashed_address_nibble = int(hashed_address[nibble_index], 16)

           if hashed_address_nibble > 7:

               checksummed_buffer += character.upper()

           else:

               checksummed_buffer += character

       else:

           raise eth_utils.ValidationError(

               f"Unrecognized hex character {character!r} at position {nibble_index}"

           )

   return "0x" + checksummed_buffer

4. Now we will convert amount for ethereum using Wei

   balance = w.eth.get_balance(checksum_encoded)

   ether_value = w.fromWei(balance, 'ether')

    

5. Now we will check account signature using private key

   signed_tx = w.eth.account.sign_transaction(tx, private_key1)

    

6. Now we will send the transaction

   tx_hash = w.eth.sendRawTransaction(signed_tx.rawTransaction)

    

7. Below is the full code

from web3 import Web3

def payment_by_metamask(acc1, acc2, pkey, amount, chain_id):

    res = False

    # Ropsten Test Net

    if chain_id == '0x3':

        w = Web3(Web3.HTTPProvider('https://ropsten.infura.io/v3/<API_TOKEN>'))

    # Main net

    if chain_id == '0x1':

        w = Web3(Web3.HTTPProvider('https://mainnet.infura.io/<API_TOKEN>'))

    account_1 = acc1

    private_key1 = pkey

    account_2 = acc2

    nonce = w.eth.getTransactionCount(account_1)

    addr_bytes = eth_utils.to_bytes(hexstr=account_2)

    checksum_encoded = checksum_encode(addr_bytes)

    balance = w.eth.get_balance(checksum_encoded)

    ether_value = w.fromWei(balance, 'ether')

    tx = {

        'nonce': nonce,

        'to': checksum_encoded,

        'value': w.toWei(amount, 'ether'),

        'gas': 2000000,

        'gasPrice': w.toWei('50', 'gwei')

    }

    signed_tx = w.eth.account.sign_transaction(tx, private_key1)

    # send transaction

    tx_hash = w.eth.sendRawTransaction(signed_tx.rawTransaction)

    res = w.toHex(tx_hash)

    return res