Web3.eth API — Web3.py 7.12.0 Documentation

The web3.eth object provides methods and properties to interact with Ethereum's RPC APIs under the eth_ namespace. By default, returned mappings are AttributeDict instances—immutable dictionaries allowing attribute-style key access.

Key Features

Immutable Data: Returned objects (AttributeDict) prevent field modifications but allow attribute access.
Type Hinting Note: Attribute access may break type hints; use dictionary access or disable AttributeDictMiddleware if typing is critical.

# Example: Accessing block data
block = web3.eth.get_block('latest')
block['number']    # Dictionary access
block.number       # Attribute access
block.number = 42  # Raises TypeError (immutable)

Properties

Property	Description
`default_account`	Ethereum address used as default `from` in transactions.
`default_block`	Default block identifier (default: `'latest'`).
`syncing`	Returns sync status or `False` if not syncing.
`max_priority_fee`	Suggested max priority fee (Wei) for dynamic fee transactions.
`gas_price`	Current gas price (Wei).
`accounts`	List of known accounts.
`block_number`	Latest block number (alias for `get_block_number()`).
`chain_id`	Chain ID (EIP-155); `None` if unavailable.

Methods

Blockchain Data

get_balance(account, block_identifier): Returns account balance at specified block.
get_block(block_identifier, full_transactions=False): Retrieves block data.
get_transaction(transaction_hash): Returns transaction details.
get_transaction_receipt(transaction_hash): Retrieves transaction receipt.

Transactions

send_transaction(transaction): Signs and sends a transaction.
estimate_gas(transaction): Estimates gas consumption for a transaction.

# Example: Sending a transaction
tx_hash = web3.eth.send_transaction({
    'to': '0x...',
    'from': web3.eth.accounts[0],
    'value': 12345
})

Filters

filter(filter_params): Creates event filters (logs/blocks/pending transactions).
get_filter_changes(filter_id): Returns new entries since last poll.
uninstall_filter(filter_id): Removes a filter.

Contracts

contract(address=None, abi=None): Instantiates or returns a contract class.

# Example: Deploying/interacting with a contract
Contract = web3.eth.contract(abi=...)
deployed_contract = Contract(address='0x...')

FAQs

How do I access immutable data returned by `web3.eth`?

Use either dictionary-style (block['number']) or attribute access (block.number). Modifications raise a TypeError.

What’s the recommended way to handle gas fees post-London fork?

Use maxFeePerGas and maxPriorityFeePerGas in transactions instead of gasPrice for dynamic fee support.

👉 Explore dynamic fee transactions

How can I fetch historical event logs?

Create a log filter with web3.eth.filter({'fromBlock':..., 'toBlock':...}) and poll using get_filter_changes().

👉 Learn more about Ethereum event logs


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