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:

ruby 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 )

ruby 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:

ruby 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:

ruby 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:

ruby 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

"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 contractgetabi 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 parsecallargs 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.parsecallargs tx ```

Parsing smart contract constructor arguments

Method parseconstructorargs 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.parseconstructorargs tx ```

Parsing transaction logs

Method parselogargs 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); txreceipt = web3.eth.getTransactionReceipt '0x83da408b05061a2512fe1abf065b37a6aad9ae96d604b288a3da34bf9f1af9e6' myContract.parselogargs txreceipt.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.