Web3 RPC client for Ethereum node

This Ruby Gem is used to connect and communicate with Ethereum node ( geth, parity, etc), having RPC interface. Also it has support to call Etherscan API.

What you can do using this GEM:

• use Web3 eth interface methods to read blocks, transactions
• query Etherscan to get ABI for validated contracts
• parse transaction method calls according to ABI
• parse transaction logs according to ABI
• parse contract creation arguments accroding to ABI
• list internal transaction using parity extended trace JSONRPC API

Installation

Add this line to your application's Gemfile:

gem 'web3-eth'

And then execute:

$ bundle

Or install it yourself as:

$ gem install web3-eth

Usage

Connect

Connecting to local node ( or by SSH Tunnel )

web3 = Web3::Eth::Rpc.new

To connect to remote Ethereum node, follow instructions: https://github.com/paritytech/parity/wiki/Wallet-Remote-Access

If you need to connect to remote host, you can specify host, port and HTTP connection options:

web3 = Web3::Eth::Rpc.new host: 'node.host.com', 
                          port: 8545,  
                          connect_options: { use_ssl: true, read_timeout: 120 } 

HTTP connection options are from Ruby HTTP plus additional optional property rpc_path - path to RPC interface.

For example, to connect to infura node, you need the following configuration:

web3 = Web3::Eth::Rpc.new host: 'mainnet.infura.io', 
                          port: 443,  
                          connect_options: {
                            open_timeout: 20,
                            read_timeout: 140,
                            use_ssl: true,
                            rpc_path: '/<YOUR INFURA PERSONAL KEY>'
                          }

or to connect to Ropsten:

web3 = Web3::Eth::Rpc.new host: 'ropsten.infura.io', 
                          port: 443,  
                          connect_options: {
                            open_timeout: 20,
                            read_timeout: 140,
                            use_ssl: true
                          }

Calling eth interface

>> web3.eth.blockNumber
4376369

>> web3.eth.getBalance '0x829BD824B016326A401d083B33D092293333A830'
3916.6597314456685

>> block = web3.eth.getBlockByNumber 4376369
#<Web3::Eth::Block:0x007f844d6f1138 @block_data={"author"=>"0x829bd824b016326a401d083b33d092293333a830", ...

>> block.timestamp_time
2017-10-17 12:51:36 +0300

>> block.transactions.count
129

>> block.transactions[0].from
"0xb2930b35844a230f00e51431acae96fe543a0347"

>> block.transactions[0].value_eth
0.51896811

Calling Etherscan API:

api = Web3::Eth::Etherscan.new 'Your API Key'
abi = api.contract_getabi address: '0xe3fedaecd47aa8eab6b23227b0ee56f092c967a9'

Method name for Etherscan must be constructed as _, for example contract_getabi calls method getabi in module contract

If method accepts only one parameter address, the call can be simplified to:

abi = api.contract_getabi '0xe3fedaecd47aa8eab6b23227b0ee56f092c967a9'

Accesing contract methods

# creation of contract object
myContract = web3.eth.contract(abi);

# initiate contract for an address
myContractInstance = myContract.at('0x2ad180cbaffbc97237f572148fc1b283b68d8861');

# call constant function
result = myContractInstance.balanceOf('0x...'); # any constant method works
puts result 

or using Etherscan API ( requires contract ABI be published in Etherescan ):

api = Web3::Eth::Etherscan.new 'Your API Key'
myContractInstance = web3.eth.load_contract(api, '0x2ad180cbaffbc97237f572148fc1b283b68d8861')

// call constant function
result = myContractInstance.balanceOf('0x....'); # any constant method works
puts result // '0x25434534534'

Parsing transaction call arguments

Method parse_call_args parses call arguments according to ABI. Code example is:

api = Web3::Eth::Etherscan.new 'Your API Key'
abi = api.contract_getabi address: '0x2ad180cbaffbc97237f572148fc1b283b68d8861'

myContract = web3.eth.contract(abi);
tx = web3.eth.getTransactionByHash '0x83da408b05061a2512fe1abf065b37a6aad9ae96d604b288a3da34bf9f1af9e6'
myContract.parse_call_args tx

Parsing smart contract constructor arguments

Method parse_constructor_args parses smart contract creation arguments according to ABI. Code example is:

api = Web3::Eth::Etherscan.new 'Your API Key'
abi = api.contract_getabi address: '0xf4702b0918a8a89dfc38459ce42198834818f26b'

myContract = web3.eth.contract(abi);
tx = web3.eth.getTransactionByHash '0x35f0cf1d1c7ec14dd40fe3949d1c535ec3f3953f118cb9dc1394370f966cf957'
myContract.parse_constructor_args tx

Parsing transaction logs

Method parse_log_args parses indexed and not-indexed log event arguments according to ABI. Code example is:

api = Web3::Eth::Etherscan.new 'Your API Key'
abi = api.contract_getabi address: '0x2ad180cbaffbc97237f572148fc1b283b68d8861'

myContract = web3.eth.contract(abi);
tx_receipt = web3.eth.getTransactionReceipt '0x83da408b05061a2512fe1abf065b37a6aad9ae96d604b288a3da34bf9f1af9e6'
myContract.parse_log_args tx_receipt.logs.first

Listing internal transactions

To use this feature, you should run parity node with the option --tracing on, refer to [https://github.com/paritytech/parity/wiki/Configuring-Parity#cli-options].

calls = web3.trace.internalCallsByHash '0x7ac18a1640e443cd069ff51da382b92b585e42dae8f38db0932380bfe86908a6'
puts calls.first.from
puts calls.first.to
puts calls.first.value_eth

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/izetex/web3-eth. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.