Repositories

SteemRubyTutorial

All examples from this tutorial can be found as fully functional scripts on GitHub:

• SteemRubyTutorial
• radiator sample code: Steem-Print-Balances.rb.

radiator

Radiator is one of the tree Ruby APIs to the Steem Blockchain.

• Project Name: Radiator
• Repository: https://github.com/inertia186/radiator
• Official Documentation: https://www.rubydoc.info/gems/radiator
• Official Tutorial: https://developers.steem.io/tutorials-ruby/getting_started

Steem Engine

• Project Name: Steem Engine
• Home Page: https://steem-engine.com
• Repository: https://github.com/harpagon210/steem-engine
• Official Documentation: https://github.com/harpagon210/sscjs (JavaScript only)
• Official Tutorial: N/A

What Will I Learn?

This tutorial shows how to interact with the Steem blockchain, Steem database and Steem Engine using Ruby. When accessing Steem Engine using Ruby their only the radiator APIs available.

In this particular chapter you learn how extend Steem-Print-Balances.rb from the Print Account Balances improved tutorial so it prints the steem engine token as well.

Requirements

Basic knowledge of Ruby programming is needed. It is necessary to install at least Ruby 2.5 as well as the following ruby gems:

gem install bundler
gem install colorize
gem install contracts
gem install radiator

The tutorial build on top of the following previous chapters:

• Print Steem Engine Token values
• Print Account Balances improved

Difficulty

For reader with programming experience this tutorial is basic level.

Tutorial Contents

Just like the last tutorial the majority of the work is done inside a newly written class. This class can read the ballances from the database and converts the JSON objects returned into propper ruby classes.

Implementation using radiator

---

A simple standard constructor for the various properties a balance holds:

Property	Description
symbol	ID of token held
account	ID of account holding
balance	balance held
stake	balance staked
delegated_stake	stake delegated
received_stake	stake stake
pending_unstake	delegated stake to be returned to owner.
loki	some internal informations

module SCC
   class Balance < SCC::Steem_Engine
      include Contracts::Core
      include Contracts::Builtin

      attr_reader :key, :value,
                  :symbol,
                  :account,
                  :balance,
                  :stake,
                  :delegated_Stake,
                  :received_stake,
                  :pending_unstake,
                  :loki

      public

         Contract Any => nil
         def initialize(balance)
            super(:symbol, balance.symbol)

            @symbol          = balance.symbol
            @account         = balance.account
            @balance         = balance.balance.to_f
            @stake           = balance.stake.to_f
            @delegated_stake = balance.delegatedStake.to_f
            @received_stake  = balance.receivedStake.to_f
            @pending_unstake = balance.pendingUnstake.to_f
            @loki            = balance["$loki"]

            return
         end

Convert the balance into steem using the Metric class from Print Steem Engine Token values tutorial.

         Contract None => Radiator::Type::Amount
         def to_steem
            _steem = if @symbol == "STEEMP" then
               @balance
            else
               @balance * metric.last_price
            end

            return Radiator::Type::Amount.to_amount(
               _steem,
               Radiator::Type::Amount::STEEM)
         end

Convert the current balance into SBD using the Amount class from the Print Account Balances improved tutorial.

         Contract None => Radiator::Type::Amount
         def to_sbd
            return to_steem.to_sbd
         end

The metrics for the balance as lazy initialised property. The metric is used to convert the balance into Steem.

         Contract None => SCC::Metric
         def metric
            if @metric == nil then
               @metric = SCC::Metric.symbol @symbol
            end

            return @metric
         end

The token information of the balance also as lazy initialised property. The token informations contain, among other, the display name of the token which we will later use.

         Contract None => SCC::Token
         def token
            if @token == nil then
               @token = SCC::Token.symbol @symbol
            end

            return @token
         end

Create a colourised string showing the amount in SDB, STEEM and the steem engine token. The actual value is colourised in blue while the converted values are colourised in grey (aka dark white).

A try catch is used for token which have no metics and therefore no steem value. "N/A" is then printed instead of the steem values.

         Contract None => String
         def to_ansi_s
            begin
               _steem = self.to_steem
               _sbd   = self.to_sbd

               _retval = (
               "%1$15.3f %2$s".white +
                  " " +
                  "%3$15.3f %4$s".white +
                  " " +
                  "%5$18.6f %6$s".blue) % [
                  _sbd.to_f,
                  _sbd.asset,
                  _steem.to_f,
                  _steem.asset,
                  @balance,
                  @symbol]
            rescue KeyError
               _na = "N/A"

               _retval = (
               "%1$15s %2$s".white +
                  " " +
                  "%3$15s %4$5s".white +
                  " " +
                  "%5$18.6f %6$s".blue) % [
                  _na,
                  _na,
                  _na,
                  _na,
                  @balance,
                  @symbol]
            end

            return _retval
         end

Get the list of balances for a gives account using the find function from contracs API. The find function has been explained in the Print Steem Engine Token values tutorial.

         class << self
            Contract String => ArrayOf[SCC::Balance]
            def account (name)
               _retval  = []
               _current = 0
               _query   = {
                  "account": name
               }

               loop do
                  # Read the next batch of balances using
                  # the find function.
                  #
                  _balances = Steem_Engine.contracts_api.find(
                     contract:   "tokens",
                     table:      "balances",
                     query:      _query,
                     limit:      SCC::Steem_Engine::QUERY_LIMIT,
                     offset:     _current,
                     descending: false)

                  # Exit loop when no result set is
                  # returned.
                  #
               break if (not _balances) || (_balances.length == 0)

                  # convert each returned JSON object into
                  # a class instance.
                  #
                  _retval += _balances.map do |_balance|
                     SCC::Balance.new _balance
                  end

                  # Move current by the actual amount of
                  # rows returned
                  #
                  _current = _current + _balances.length
               end

               return _retval
            end
         end # self
   end # Balance
end # SCC

In addition to this method the balance class committed to git has examples for retrieving the balances for a given token and all balances in the database. All three methods are very similar. For this only the one method which is actually needed for the final script has been described.

Hint: Follow this link to Github for the complete script with comments and syntax highlighting : Balance.rb.

---

Most of the Steem-Print-Balances.rb script has already been described in Print Account Balances improved and there are only few changes needed to print the steem engine balances as well:

Most of the functionality is not encapsulated in classes which have been explained previously. All that is needed is too require those classes.

require_relative 'Radiator/Amount'
require_relative 'Radiator/Price'
require_relative 'SCC/Balance'
require_relative 'SCC/Token'

First print the account value without the steem engine token added.

      puts(("  Account Value (steem)= " + "%1$15.3f %2$s".green) % [
         _account_value.to_f,
         _account_value.asset])

Then retrieve all balances for the currently account from the steem engine database

      _scc_balances = SCC::Balance.account account.name

Loop over all balances printing the balance and adding the value (in SBD) to the account value. For the latter a try catch is used for token which don't have a Steem value.

      _scc_balances.each do |_scc_balance|
         token = _scc_balance.token

         puts("  %1$-20.20s = %2$s" % [token.name, _scc_balance.to_ansi_s])

         begin
            _sbd           = _scc_balance.to_sbd
            _account_value = _account_value + _sbd
         rescue KeyError
            # do nothing.
         end
      end

Lastly print the account value with the value of the steem engine token added.

      puts(("  Account Value (total)= " + "%1$15.3f %2$s".green) % [
         _account_value.to_f,
         _account_value.asset])

Hint: Follow this link to Github for the complete script with comments and syntax highlighting : Steem-Print-Balances.rb.

---

The output of the command changes from previous only printing the steem token:

to now printing the values of the Steem Engine Token as well:

Curriculum

First tutorial

• Using Steem-API with Ruby Part 1

Previous tutorial

• Using Steem-API with Ruby Part 15

Next tutorial

• Using Steem-API with Ruby Part 17

Proof of Work

• GitHub: SteemRubyTutorial Issue #18

Image Source

• Ruby symbol: Wikimedia, CC BY-SA 2.5.
• Steemit logo Wikimedia, CC BY-SA 4.0.
• Steem Engine logo Steem Engine
• Screenshots: Hive account@krischik, CC BY-NC-SA 4.0