How to connect to the Ethereum network using Ruby

Ruby has a huge fanbase. Ruby was developed by its creator with an intention to create a language people can have fun using. Ruby has been largely accepted by the developers all around the world since it’s launch, in fact, the biggest tech communities in many cities are ruby communities. In this article, we will learn how to connect to ethereum network using Ruby, ethereum.rb is a package which can be used to connect to ethereum blockchain network and help us easily accomplish meaningful things.

By using ethereum.rb you can make direct JSON RPC calls to the node from any ruby application, it has simple syntax, you can compile Solidity contracts with solc compiler from ruby, receive events from contract, and is programmer-friendly. You can also sign Ethereum transactions using another Ruby gem ruby-eth which allows separation of key and node management. Sign transactions and handle keys anywhere you can run ruby, broadcast transactions through any node.

Before installing the gem let's make sure that ruby is installed. Simply open a terminal and run:

$ ruby -v

Once we ensure ruby is installed and at the right version (2.0+), let's move forward and install the ethereum.rb gem which will help us connect to ethereum blockchain network using ruby language, You can install it from the command line using RubyGems the package manager for ruby:

$ gem install ethereum.rb

If you're using macOS you may encounter a permission related problem while installing gem that is because the version of Ruby that ships with macOS is usually for Apple's own use, you can always make few changes and get going but I won't recommend that.

Instead of that, I'll suggest using rbenv or RVM (Ruby Version Manager) to manage a separate Ruby version, which will be installed into a sandbox in your home directory, that you can make changes to without worrying about messing up the system Ruby. 

For our purposes today, we would have to use OpenEthereum (fka Parity) because ethereum.rb only works with OpenEthereum. Since that is a bit too involved for just querying for block height, we'll just grab a free endpoint from QuikNode to make this easy. After you've created your free ethereum endpoint, copy your HTTP Provider endpoint:

You'll need this later, so copy it and save it.

Now let's create a short script, let's call it `index.rb`, to fetch the block height from our node. You can copy/paste this into your code editor:

require 'ethereum.rb'
client = Ethereum::HttpClient.new('YOUR_ETHEREUM_NODE_URL')
blockNumber = client.eth_block_number
puts blockNumber["result"].to_i(16)

So go ahead and replace `ADD_YOUR_ETHEREUM_NODE_URL` with the http provider from the instructions above.

A quick explanation of the code above - we are importing the ethereum.rb gem we installed earlier (line 1), setting our Ethereum node URL (line 2), we are getting the latest Ethereum block number using client.eth_block_number API (line 3)and Printing the block number but as the API returns the block number in hexadecimal, we will convert it in decimal using to_i(16) function (lines 4).

Save this code snippet in a file index.rb we're going to run this very shortly.

Run the file by running the following in a terminal:

$ ruby index.rb

After running this command we will see the latest Ethereum block number as shown below.

That’s it we have connected through Ethereum network using ethereum.rb gem for Ruby. In addition, also check out other Ethereum library in ruby, ruby-eth.

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