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import requests
from web3 import Web3
from typing import Dict, Any
class TokenApprovalHelper:
def __init__(self, web3: Web3, private_key: str):
self.web3 = web3
self.private_key = private_key
def approve_token(self, erc20_contract_address: str, exchange_proxy_address: str, sell_amount: str, eth_address: str) -> Dict[str, Any]:
"""
Approves the 0x Exchange Proxy contract to spend the specified amount of the ERC-20 token.
Args:
erc20_contract_address (str): The address of the ERC-20 token contract.
exchange_proxy_address (str): The address of the 0x Exchange Proxy contract.
sell_amount (str): The amount of the token to approve.
eth_address (str): Your Ethereum address.
Returns:
dict: The transaction receipt of the approval transaction.
Example:
>>> approve_token('0xTokenAddress', '0xProxyAddress', '1000000000000000000', '0xYourAddress')
"""
erc20_abi = [
{
"constant": False,
"inputs": [
{
"name": "_spender",
"type": "address"
},
{
"name": "_value",
"type": "uint256"
}
],
"name": "approve",
"outputs": [
{
"name": "",
"type": "bool"
}
],
"type": "function"
}
]
erc20_contract = self.web3.eth.contract(address=erc20_contract_address, abi=erc20_abi)
approve_tx = erc20_contract.functions.approve(
exchange_proxy_address,
int(sell_amount)
).buildTransaction({
'from': eth_address,
'nonce': self.web3.eth.getTransactionCount(eth_address),
'gas': 100000,
'gasPrice': self.web3.toWei('20', 'gwei')
})
signed_approve_tx = self.web3.eth.account.signTransaction(approve_tx, private_key=self.private_key)
tx_hash = self.web3.eth.sendRawTransaction(signed_approve_tx.rawTransaction)
return self.web3.eth.waitForTransactionReceipt(tx_hash)
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