def call_contract_function(contract,
function_name,
transaction,
*args,
**kwargs):
"""
Helper function for interacting with a contract function using the
`eth_call` API.
"""
call_transaction = contract._prepare_transaction(
fn_name=function_name,
fn_args=args,
fn_kwargs=kwargs,
transaction=transaction,
)
return_data = contract.web3.eth.call(call_transaction)
function_abi = contract._find_matching_fn_abi(function_name, args, kwargs)
output_types = get_abi_output_types(function_abi)
try:
output_data = decode_abi(output_types, return_data)
except DecodingError as e:
# Provide a more helpful error message than the one provided by
# eth-abi-utils
is_missing_code_error = (
return_data in ACCEPTABLE_EMPTY_STRINGS and
contract.web3.eth.getCode(contract.address) in ACCEPTABLE_EMPTY_STRINGS
)
if is_missing_code_error:
msg = (
"Could not transact with/call contract function, is contract "
"deployed correctly and chain synced?"
)
else:
msg = (
"Could not decode contract function call {} return data {} for "
"output_types {}".format(
function_name,
return_data,
output_types
)
)
raise BadFunctionCallOutput(msg) from e
normalizers = itertools.chain(
BASE_RETURN_NORMALIZERS,
contract._return_data_normalizers,
)
normalized_data = map_abi_data(normalizers, output_types, output_data)
if len(normalized_data) == 1:
return normalized_data[0]
else:
return normalized_data
def call_contract_function(contract,
function_name,
transaction,
*args,
**kwargs):
"""
Helper function for interacting with a contract function using the
`eth_call` API.
"""
call_transaction = contract._prepare_transaction(
fn_name=function_name,
fn_args=args,
fn_kwargs=kwargs,
transaction=transaction,
)
return_data = contract.web3.eth.call(call_transaction)
function_abi = contract._find_matching_fn_abi(function_name, args, kwargs)
output_types = get_abi_output_types(function_abi)
try:
output_data = decode_abi(output_types, return_data)
except DecodingError as e:
# Provide a more helpful error message than the one provided by
# eth-abi-utils
msg = (
"Could not decode contract function call {} return data {} for "
"output_types {}".format(
function_name,
return_data,
output_types
)
)
raise_from(BadFunctionCallOutput(msg), e)
normalized_data = [
normalize_return_type(data_type, data_value)
for data_type, data_value
in zip(output_types, output_data)
]
if len(normalized_data) == 1:
return normalized_data[0]
else:
return normalized_data