Web3.py: Consider adding Chain Id to library

[nueverest]

• Version: 4.0.0-b
• Python: 3.6.3
• OS: linux

What was wrong?

No clear way to access known chain ids.

How can it be fixed?

Proposed syntax

>>> from web3 import Chains
>>> Chains.Ropsten.id
3

I ran into issues here: https://web3py.readthedocs.io/en/latest/web3.eth.account.html#sign-a-contract-transaction as buildTransaction() requires a chainId. I didn't even know the chains had ids.

>>> unicorn_txn = unicorns.functions.transfer(
...     '0xfB6916095ca1df60bB79Ce92cE3Ea74c37c5d359',
...     1,
... ).buildTransaction({
...     'chainId': 1,
...     'gas': 70000,
...     'gasPrice': w3.toWei('1', 'gwei'),
...     'nonce': nonce,
... })

Maybe this will help others

According to this answer https://ethereum.stackexchange.com/a/17101/7187 the chain ids are as follows:

0: Olympic, Ethereum public pre-release testnet
1: Frontier, Homestead, Metropolis, the Ethereum public main network
1: Classic, the (un)forked public Ethereum Classic main network, chain ID 61
1: Expanse, an alternative Ethereum implementation, chain ID 2
2: Morden, the public Ethereum testnet, now Ethereum Classic testnet
3: Ropsten, the public cross-client Ethereum testnet
4: Rinkeby, the public Geth PoA testnet
42: Kovan, the public Parity PoA testnet
77: Sokol, the public POA Network testnet
99: Core, the public POA Network main network
7762959: Musicoin, the music blockchain

[carver]

Yeah, looks like this needs documentation (and maybe renaming, because it's not intuitive to me):
w3.version.network will give you the chain ID.

[scottydelta]

Just renaming network in web3.version to chainId will be enough? Would it make sense to return name based on the chain ID aswell?

[carver]

The unintuitive part to me is the module name version. Unfortunately chain id and network id seem to be used interchangeably in a lot of places, so someone will be confused no matter which we pick. Maybe we should even just have both names.

[scottydelta]

can we rename version to something like info and have chainId return the chain id and it can have an alias of networkId for the reason you mentioned above?

[carver]

The thing most consistent with https://github.com/ethereum/wiki/wiki/JSON-RPC would be to call it net.

[nueverest]

The terms network and chain could be combined: networkchain or networkchainid

If net is used does that imply that chainId inside of the transaction dict will change to net for consistency?

transaction = {
        'chainId': 1     # chainId --> 'net'
        'to': address,
        'from': w3.eth.coinbase,
        'data': '',
        'value': 1000,
        'gas': gas_limit_hex,
        'gasPrice': gas_price_hex,
        'nonce': nonce_hex,        
    }

[carver]

Ah, to clarify: because net is the prefix of the json-rpc call net_version, the most consistent with that spec would be: w3.net.version (and if we wanted to alias it, something like: w3.net.id or w3.net.chainId)

[nueverest]

I like w3.net.chainId.