Installation

1. Add exw3 to your list of dependencies in mix.exs:

   def deps do [{:exw3, "~> 0.1.0"}] end

2. Ensure exw3 is started before your application:

   def application do [applications: [:exw3]] end

Overview

ExW3 is a wrapper around ethereumex to provide a high level, and user friendly json rpc api. It currently only supports Http. The primary feature it provides is a handy abstraction for working with smart contracts.

Usage

Ensure you have an ethereum node to connect to at the specified url in your config. Any easy local testnet to use is ganache-cli:

ganache-cli

Make sure your config includes:

config :ethereumex,
  url: "http://localhost:8545"

Currently ExW3 supports a handful of json rpc commands. Mostly just the useful ones. If it doesn't support those specific commands you can always use the Ethereumex commands.

iex(1)> accounts = ExW3.accounts()
["0xb5c17637ccc1a5d91715429de76949fbe49d36f0",
 "0xecf00f60a29acf81d7fdf696fd2ca1fa82b623b0",
 "0xbf11365685e07ad86387098f27204700d7568ee2",
 "0xba76d611c29fb25158e5a7409cb627cf1bd220cf",
 "0xbb209f51ef097cc5ca320264b5373a48f7ee0fba",
 "0x31b7a2c8b2f82a92bf4cb5fd13971849c6c956fc",
 "0xeb943cee8ec3723ab3a06e45dc2a75a3caa04288",
 "0x59315d9706ac567d01860d7ede03720876972162",
 "0x4dbd23f361a4df1ef5e517b68e099bf2fcc77b10",
 "0x150eb320428b9bc93453b850b4ea454a35308f17"]
iex(2)> ExW3.balance(Enum.at(accounts, 0))
99999999999962720359
iex(3)> ExW3.block_number()
835
iex(4)> simple_storage_abi = ExW3.load_abi("test/examples/build/SimpleStorage.abi")
%{
  "get" => %{
    "constant" => true,
    "inputs" => [],
    "name" => "get",
    "outputs" => [%{"name" => "", "type" => "uint256"}],
    "payable" => false,
    "stateMutability" => "view",
    "type" => "function"
  },
  "set" => %{
    "constant" => false,
    "inputs" => [%{"name" => "_data", "type" => "uint256"}],
    "name" => "set",
    "outputs" => [],
    "payable" => false,
    "stateMutability" => "nonpayable",
    "type" => "function"
  }
}
iex(5)> ExW3.Contract.start_link(SimpleStorage, abi: simple_storage_abi)
{:ok, #PID<0.239.0>}
iex(6)> {:ok, address} = ExW3.Contract.deploy(SimpleStorage, bin: ExW3.load_bin("test/examples/build/SimpleStorage.bin"), options: %{gas: 300000, from: Enum.at(accounts, 0)})
{:ok, "0xd99306b81bd61cb0ecdd3f2c946af513b3395088"}
iex(7)> ExW3.Contract.at(SimpleStorage, address)
:ok
iex(8)> ExW3.Contract.call(SimpleStorage, :get)
{:ok, 0}
iex(9)> ExW3.Contract.send(SimpleStorage, :set, [1], %{from: Enum.at(accounts, 0)})
{:ok, "0xb7e9cbdd2cec8ca017e675059a3af063d754496c960f156e1a41fe51ea82f3b8"}
iex(10)> ExW3.Contract.call(SimpleStorage, :get)                                
{:ok, 1}

Compiling Solidity

Ensure you have solc installed:

solc --version

Then if you've made changes to the example contracts you can compile them like this:

mix solc