Using Steem-API with Ruby Part 7 — Print Posting Votes
All examples from this tutorial can be found as fully functional scripts on GitHub:
- steem-api sample code: Steem-Dump-Posting-Votes.rb
- radiator sample code: Steem-Print-Posting-Votes.rb.
- Project Name: Steem Ruby
- Repository: https://github.com/steemit/steem-ruby
- Official Documentation: https://github.com/steemit/steem-ruby
- Official Tutorial: N/A
- 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
What Will I Learn?
This tutorial shows how to interact with the Steem blockchain and Steem database using Ruby. When using Ruby you have two APIs available to chose: steem-api and radiator which differentiates in how return values and errors are handled:
- steem-api uses closures and exceptions and provides low level computer readable data.
- radiator uses classic function return values and provides high level human readable data.
Since both APIs have advantages and disadvantages sample code for both APIs will be provided so the reader ca decide which is more suitable.
This chapter teaches how to display all up and downvotes in present on any posting. In the next part will teach how to calculate the value in SBD for each post.
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 steem-ruby gem install radiator
Note: Both steem-ruby and radiator provide a file called
steem.rb. This means that:
- When both APIs are installed ruby must be told which one to use.
- Both APIs can't be used in the same script.
If there is anything not clear you can ask in the comments.
For reader with programming experience this tutorial is basic level.
Information on the postings are accessed via the
get_active_votes method of the
CondenserApi. The method takes two parameter: the authors name and the id of the posting. Both can be extracted from the URL of the posting. As Result you get an array of voting results:
|voter||Name of the voter.|
|percent||percentage of vote (times 10000).|
|weight||Used to calculate the vote value.|
|rshares||Used to calculate the vote value.|
|reputation||Voters reputation. Not used any more and always 0.|
|time||Time and date of the actual vote.|
A little reminder: A % sign behind the number usually means that the number was multiplied by 100. So 1% equals 0.01 and 100% equals 1.0. Steem itself however doesn't use floating-point numbers and multiplies the percentage with 10000 instead to make them integers while still allowing for a 0.0001 / 0.01% precision.
The correct use if
rshares is rather complex and will be described in a separate tutorial.
Implementation using steem-ruby
To ease the use of the voting values we define a
Value class which does all the a parsing and converts the integer values into floating points as well as converting time stamps ti the
Time instances. Note that floating point values are not as precise but easier to use the fixed points numbers.
Class to handle vote values from postings.
class Vote < Steem::Type::BaseType include Contracts::Core include Contracts::Builtin attr_reader :voter, :percent, :weight, :rshares, :reputation, :time
Create a new instance from the data returned from the
get_active_votes method. The percent is divided by 10000 to make the value mathematically correct.
Contract HashOf[String => Or[String, Num]] => nil def initialize(value) super(:vote, value) @voter = value.voter @percent = value.percent / 10000.0 @weight = value.weight @rshares = value.rshares @reputation = value.reputation @time = Time.strptime(value.time + "Z" , "%Y-%m-%dT%H:%M:%S") return end
Create a colorised string from the instance. The vote percentages are multiplied with 100 and are colorised (positive values are printed in green, negative values in red and zero votes (yes they exist) are shown in grey), for improved human readability.
Contract None => String def to_ansi_s _percent = @percent * 100.0 return ( "%1$-16s : " + "%2$7.2f%%".colorize( if _percent > 0 then :green elsif _percent < 0 then :red else :white end ) + "%3$12d" + "%4$15d" + "%5$20s") % [ @voter, _percent, @weight, @rshares, @time.strftime("%Y-%m-%d %H:%M:%S")] end
Print a list a vote values:
- Loop over all votes.
- convert the vote JSON object into the ruby
- print as ansi strings.
Contract ArrayOf[HashOf[String => Or[String, Num]] ] => nil def self.print_list (votes) votes.each do |vote| _vote = Vote.new vote puts _vote.to_ansi_s end return end
Print the votes from a postings given as URLs:
- Extract the posting ID and author name from the URL with standard string operations.
- Print a short header
- Request the list of votes from
- print the votes.
Contract String => nil def self.print_url (url) _slug = url.split('@').last _author, _permlink = _slug.split('/') puts ("Post Author : " + "%1$s".blue) % _author puts ("Post ID : " + "%1$s".blue) % _permlink puts ("Voter name : percent weight rshares vote date & time") Condenser_Api.get_active_votes(_author, _permlink) do |votes| if votes.length == 0 then puts "No votes found.".yellow else Vote.print_list votes end rescue => error Kernel::abort(("Error reading posting “%1$s”:\n".red + "%2$s") % [_permlink, error.to_s]) end return end end
To avoid replications the rest of the operation is described in the radiator chapter.
Hint: Follow this link to Github for the complete script with comments and syntax highlighting: Steem-Dump-Posting-Votes.rb.
The output of the command (for the steem account) looks like this:
Implementation using radiator
To avoid replications the
Vote class is only described in the steem-ruby chapter
create instance to the steem condenser API which will give us access to the active votes.
Condenser_Api = Radiator::CondenserApi.new rescue => error
I am using
Kernel::abort so the script ends when data can't be loaded
Kernel::abort("Error reading global properties:\n".red + error.to_s) end
Display help if no URL are given.
if ARGV.length == 0 then puts " Steem-Print-Posting-Votes — Print voting on account. Usage: Steem-Print-Posting-Votes URL … " else
Loop over all URLs given and print the values using the Vote class.
ARGV.each do |_url| Vote.print_url _url end end
Hint: Follow this link to Github for the complete script with comments and syntax highlighting : Steem-Print-Posting-Votes.rb.
The output of the command (for the steem account) looks similar to the previous output:
This time a posting with a negative vote in red is shown.
Proof of Work
- GitHub Task: SteemRubyTutorial Issue #9
- Ruby symbol: Wikimedia, CC BY-SA 2.5.
- Steemit logo Wikimedia, CC BY-SA 4.0.
- Screenshots: @krischik, CC BY-NC-SA 4.0