[Ethereum] Cannot import Web3 from web3

web3.py

I've repeatedly installed web3 via pip on an ubuntu OS (17.04, running on a DigitalOcean droplet) but for some reason when I attempt to run "from web3 import Web3" I get this response:

ModuleNotFoundError: No module named 'web3'

I think it has to do with pip because I've had trouble installing other modules (eth-testrpc). Any advice?

Best Answer

From the terminal, install Web3.py using pip with the following command:

pip install web3

To use the web3 library you will need to instantiate a Web3 object:

>>> from web3 import Web3, HTTPProvider, IPCProvider
>>> web3 = Web3(HTTPProvider('http://localhost:8545'))

>>> web3.eth.blockNumber
4000000

or for an IPC based connection

>>> web3 = Web3(IPCProvider())

Note that you should create only one RPCProvider per process, as it recycles underlying TCP/IP network connections between your process and Ethereum node.

Related Solutions

[Ethereum] Cannot create filter on Infura via web3.py

Infura doesn't support filters.

Per https://api.infura.io/v1/jsonrpc/ropsten/methods (from the documentation, these are the supported methods:

{
  "get": [
    "web3_clientVersion",
    "net_version",
    "net_listening",
    "net_peerCount",
    "eth_protocolVersion",
    "eth_syncing",
    "eth_mining",
    "eth_hashrate",
    "eth_gasPrice",
    "eth_accounts",
    "eth_blockNumber",
    "eth_getBalance",
    "eth_getStorageAt",
    "eth_getTransactionCount",
    "eth_getBlockTransactionCountByHash",
    "eth_getBlockTransactionCountByNumber",
    "eth_getUncleCountByBlockHash",
    "eth_getUncleCountByBlockNumber",
    "eth_getCode",
    "eth_call",
    "eth_estimateGas",
    "eth_getBlockByHash",
    "eth_getBlockByNumber",
    "eth_getTransactionByHash",
    "eth_getTransactionByBlockHashAndIndex",
    "eth_getTransactionByBlockNumberAndIndex",
    "eth_getTransactionReceipt",
    "eth_getUncleByBlockHashAndIndex",
    "eth_getUncleByBlockNumberAndIndex",
    "eth_getCompilers",
    "eth_getLogs",
    "eth_getWork"
  ],
  "post": [
    "eth_sendRawTransaction",
    "eth_call",
    "eth_estimateGas",
    "eth_submitWork",
    "eth_submitHashrate"
  ]
}

[Ethereum] Getting Tokens Transferred from Web3.py

It searches for all events:

Which have been emitted by the designated ERC20 token contract, which in your case is:

To: Contract 0xc73e0383f3aff3215e6f04b0331d58cecf0ab849

This value should appear in the to field of the transaction receipt
Whose first topic (topics[0]) is equal to the hash of the signature of the Transfer event:

In Javascript, this value is Web3.utils.keccak256("Transfer(address,address,uint256)")

You may use the equivalent code in Python if you need to...

Best Answer

Related Solutions

[Ethereum] Cannot create filter on Infura via web3.py

[Ethereum] Getting Tokens Transferred from Web3.py

Related Topic