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https://github.com/blockchain-etl/ethereum-etl.git
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77 lines
3.1 KiB
Python
77 lines
3.1 KiB
Python
# MIT License
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#
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# Copyright (c) 2018 Evgeny Medvedev, evge.medvedev@gmail.com
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in all
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# copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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from web3.exceptions import BadFunctionCallOutput
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from ethereumetl.domain.erc20_token import EthErc20Token
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from ethereumetl.erc20_abi import ERC20_ABI
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class EthErc20TokenService(object):
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def __init__(self, web3, function_call_result_transformer=None):
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self._web3 = web3
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self._function_call_result_transformer = function_call_result_transformer
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def get_token(self, token_address):
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checksum_address = self._web3.toChecksumAddress(token_address)
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contract = self._web3.eth.contract(address=checksum_address, abi=ERC20_ABI)
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symbol = self._call_contract_function(contract.functions.symbol())
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name = self._call_contract_function(contract.functions.name())
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decimals = self._call_contract_function(contract.functions.decimals())
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total_supply = self._call_contract_function(contract.functions.totalSupply())
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token = EthErc20Token()
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token.erc20_token_address = token_address
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token.erc20_token_symbol = symbol
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token.erc20_token_name = name
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token.erc20_token_decimals = decimals
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token.erc20_token_total_supply = total_supply
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return token
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def _call_contract_function(self, func):
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# BadFunctionCallOutput exception happens if the token doesn't implement a particular function
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# or was self-destructed
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# OverflowError exception happens if the return type of the function doesn't match the expected type
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result = call_contract_function(
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func=func,
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ignore_errors=(BadFunctionCallOutput, OverflowError),
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default_value=None)
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if self._function_call_result_transformer is not None:
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return self._function_call_result_transformer(result)
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else:
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return result
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def call_contract_function(func, ignore_errors, default_value=None):
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try:
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result = func.call()
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return result
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except Exception as ex:
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if type(ex) in ignore_errors:
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return default_value
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else:
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raise ex
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