#ruby

TILFebruary 20, 2019by Alexander Budchanov

AND & OR Operators Precedence

Are you still sure that && and and is the same operators? Look at this:


a = true && false

a

=> false


a = true and false

a

=> true

The same situation could be reproduced for || and or. Why? The answer lies in Ruby Operator Precedence.

The first example can be represented as:


a = (true && false)

Second:


(a = true) and false

Thanks to Igor Alexandrov

TILFebruary 03, 2019by Dmitry Voronov

Use hash or case-statement in Ruby?

Often, when we need to get a value based on the other one, we're using a case-statement. Like this


def realizing_trade_type(realizable_trade_type)

  case realizable_trade_type

  when 'buy'

    'sell'

  when 'short'

    'cover'

  when 'buy_contract'

    'sell_contract'

  when 'short_contract'

    'cover_contract'

  end

end

But, if the conditions and the results are simple values, why don't we use hash for this? We can :)


REALIZING_TRADE_TYPES = {

  'buy'            => 'sell',

  'short'          => 'cover',

  'buy_contract'   => 'sell_contract',

  'short_contract' => 'cover_contract'

}.freeze

Here is the benchmark of both options, executed 10000000 times. It shows that a hash is faster in times for such the kind of usage.


>> require 'benchmark'

true

>> Benchmark.bm(15) do |x|

  x.report('hash') { 10_000_000.times { REALIZING_TRADE_TYPES['buy'] } }

  x.report('case-statement') { 10_000_000.times { realizing_trade_type 'buy' } }

  x.report('empty') { 10_000_000.times {} }

end

                      user     system      total        real

hash              0.990423   0.003412   0.993835 (  1.057612)

case-statement    1.752263   0.004531   1.756794 (  1.762030)

empty             0.380810   0.000728   0.381538 (  0.382153)

So, it's better to use a hash when you are just retrieving some values (like in the example above). If there is additional logic to execute, a case-statement is still a way to go.

TILJanuary 26, 2019by Andrey Morozov

Command for create zip archive without gem's 📁


class CreateZipCommand

  def call(files)

    # Create temp directory for files 

    tmp_dir = Dir.mktmpdir

    tmp_zip_path = File.join(tmp_dir, "files.zip")



    # Move files to the temporary folder you created above

    files.map do |file|

      download_file(file, tmp_dir)

    end



    # Go to the folder and archive the entire contents

    `cd #{tmp_dir} && zip #{tmp_zip_path} ./*`



    # Return zip path

    tmp_zip_path

  end

end



> CreateZipCommand.new.call(files)

=> "/var/folders/bk/0c864z710654sx555jpdpx9c0000gn/T/d20190126-7447-d27fpl/files.zip")



Most gems for working with archives eat a lot of memory when working with large files. This solution does not have these problems.

Make sure that the zip utility is installed on your computer - it don't work without it

TILJanuary 23, 2019by Andrey Morozov

Webhook integration in development with Ngrok 🚀

All begin when I’m using the Pipedrive (is a sales management tool designed to help small sales teams manage intricate or lengthy sales processes) webhook.

The solution was easy I just create an ngrok tunnel


> ngrok http 3000 



Session Status                online

Account                       Andrey (Plan: Free)

Version                       2.2.8

Region                        United States (us)

Web Interface                 http://127.0.0.1:4040

Forwarding                    http://b1256cb6.ngrok.io -> localhost:3000

Forwarding                    https://b1256cb6.ngrok.io -> localhost:3000

and then sent the webhook to the generated address and it works. In local development I can user webhook from another api! It's work 🚀

To use it you need to do 4 steps:

  1. Register on ngrok

  2. Download ngrok from site

  3. Connect your account

  4. Run it 🚀


ps

In addition, this service has a ngrok-tunel gem that allows you to fully integrate it with your application. But that's another story 💎

TILJanuary 07, 2019by Dmitry Voronov

How to create zip files on the fly w/o Tempfile

There are many articles about how to archive files from the server and send a zip-file to a client without persisting it on the server. But usually they don't literally do it, because they use temporary files.

There is a simple way to do it without creating any file though. You just have to put files directly to Zip::OutputStream and then read from it. Btw pay attention: you must rewind the stream before reading it.


# some files objects

def download(files)

  zip_stream = Zip::OutputStream.write_buffer do |zip|

    files.each.with_index(1) do |file, index|

     # file name must be uniq in archive

      zip.put_next_entry("#{file.name}--#{index}.#{file.extension}")

      zip.write(file.read.force_encoding('utf-8'))

    end

  end

  # important - rewind the steam

  zip_stream.rewind

  send_data zip_stream.read, 

            type: 'application/zip', 

            disposition: 'attachment', 

            filename: 'files-archive.zip'

end

LongreadsMarch 01, 2018by Eugene Komissarov

Protocol OAuth2: let’s play with Doorkeeper & Omniauth/OAuth2. Part 1.

Know your sandbox: shallow dive into OAuth2 protocol with Rails and Doorkeeper.
Read more
LongreadsFebruary 20, 2018by Igor Alexandrov

Ruby string literals VS Value objects. Overengineering?

A guide on how to get rid of string literals in Ruby with Rails 5 Attributes API
Read more
LongreadsJanuary 29, 2018by Dmitry Voronov

Dry-rb and Trailblazer Reform

Why do we use dry-rb and Trailblazer Reform on the backend?
Read more