Web3.py – How to Get Gas Estimate and Gas Price on Polygon Mumbai Chain Using Web3.py

I have deployed a contract on Goerli test net and used the following to get the estimated gas and current gas price.

contract = web3.eth.contract(address=contract_address, abi=contract_abi)    

contract_transaction_struct = contract.functions.addRow(_var1, _var2,...).buildTransaction()

gas_estimate = web3.eth.estimateGas(contract_transaction_struct)

current_gas_price = web3.eth.gasPrice

and it worked fine.

Now, I deployed the same contract on Polygom Mumbai test net.

Getting the following error

contract_transaction_struct = contract.functions.addRow(_root, _length, _secret, _file_extension, _storage_peers, _backup_peers, _upload_endpoint ).buildTransaction()   File "/usr/local/lib/python3.6/site-packages/web3/_utils/decorators.py",

line 51, in wrapper
return to_wrap(*args, **kwargs) File "/usr/local/lib/python3.6/site-packages/web3/contract.py", line 1112,
in buildTransaction
return self.build_transaction(transaction) File "/usr/local/lib/python3.6/site-packages/web3/contract.py", line 1107,
in build_transaction
**self.kwargs File "/usr/local/lib/python3.6/site-packages/web3/contract.py", line 1672,
in build_transaction_for_function
prepared_transaction = fill_transaction_defaults(web3, prepared_transaction) File "cytoolz/functoolz.pyx", line 249, in
cytoolz.functoolz.curry.call File
"/usr/local/lib/python3.6/site-packages/web3/_utils/transactions.py",
line 114, in fill_transaction_defaults
default_val = default_getter(web3, transaction) File "/usr/local/lib/python3.6/site-packages/web3/_utils/transactions.py",
line 64, in
web3.eth.max_priority_fee + (2 * web3.eth.get_block('latest')['baseFeePerGas']) File
"/usr/local/lib/python3.6/site-packages/web3/eth.py", line 690, in
get_block
return self._get_block(block_identifier, full_transactions) File "/usr/local/lib/python3.6/site-packages/web3/module.py", line 60, in
caller
null_result_formatters) File "/usr/local/lib/python3.6/site-packages/web3/manager.py", line 197, in
request_blocking
response = self._make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/manager.py", line 150, in
_make_request
return request_func(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 94, in middleware
response = make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/gas_price_strategy.py",
line 90, in middleware
return make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 94, in middleware
response = make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/attrdict.py",
line 33, in middleware
response = make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 94, in middleware
response = make_request(method, params) File "/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 96, in middleware
return _apply_response_formatters(method=method, response=response, **formatters) File
"/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 51, in _apply_response_formatters
return _format_response("result", result_formatters[method]) File
"/usr/local/lib/python3.6/site-packages/web3/middleware/formatting.py",
line 47, in _format_response
response, response_type, method_response_formatter(appropriate_response) File
"cytoolz/functoolz.pyx", line 249, in cytoolz.functoolz.curry.call
File
"/usr/local/lib/python3.6/site-packages/eth_utils/applicators.py",
line 72, in apply_formatter_if
return formatter(value) File "cytoolz/functoolz.pyx", line 249, in cytoolz.functoolz.curry.call File
"/usr/local/lib/python3.6/site-packages/eth_utils/functional.py", line
45, in inner
return callback(fn(*args, **kwargs)) File "/usr/local/lib/python3.6/site-packages/eth_utils/applicators.py",
line 84, in apply_formatters_to_dict
yield key, formatterskey File "/usr/local/lib/python3.6/site-packages/web3/middleware/validation.py",
line 79, in _check_extradata_length
len(result), MAX_EXTRADATA_LENGTH, result web3.exceptions.ExtraDataLengthError: The field extraData is 97 bytes,
but should be 32. It is quite likely that you are connected to a POA
chain. Refer to
http://web3py.readthedocs.io/en/stable/middleware.html#geth-style-proof-of-authority
for more details. The full extraData is:
HexBytes('0xd682030283626f7288676f312e31392e34856c696e7578000000000000000000ed945a3cb9bde3dd4c588e8710adb72e1668e8933f5c6d840d37e615658cbd741944e15deda7e4905984ae8c041574eee5b2daf32b7166c9457c6a71525a705b00')

I did some research and added

w3.middleware_stack.inject(geth_poa_middleware, layer=0)

Got error

w3.middleware_stack.inject(geth_poa_middleware, layer=0) AttributeError: 'Web3' object has no attribute 'middleware_stack'

I am using Web3.py version 5.31.3.

Anyways, I again chaged to

w3.add_middleware(geth_poa_middleware)

Getting the same error.

Any suggestions?

Edit: As suggested by Mikko Ohtamaa..yes was doing it wrong. the correct way to use geth_poa_middleware is

web3.middleware_onion.inject(geth_poa_middleware, layer=0)

As suggested here