Using Steem-API with Ruby Part 16 — Print Steem Engine Token balances
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:
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
Previous tutorial
Next tutorial
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:
@krischik, CC BY-NC-SA 4.0