Ruby notes 1

ruby_notes_1.md

Ruby Notes - 1

• Use is_a?, kind_of?, instance_of? method to check type of any variable

• Explain the usage of method in detail, as a comments before method

• Use compact method to remove nil from arrays

• Use tap method as follows, avoid writing an extra line to return object Instead of,

  def update_params(params)
    params[:foo] = 'bar'
    params
  end

  Use,

  def update_params(params)
    params.tap {|p| p[:foo] = 'bar' }
  end

• Instead of if condition? do_something; end, use return unless condition; do_something;. This is cleaner specifically in longer methods.

• Instead of,

  if a.present?
    a[key] = value
  else
    a = {}
    a[key] = value
  end

  use this,

  a ||= {}
  a[key] = value

• Always use 'str_value' instead of "str_value"

• Make constants for strings/numbers/regex which are used/called multiple times.

• For string replace, use String#sub(50%) OR String#tr(More than 50%) which is faster then String#gsub , so if not needed we should not use gsub.

• Should not use exceptions for control flow, instead we can put conditions. that would be 10 times faster.

• while loop is 80% faster then Array#each_with_index when we have bigger array, but more lines of code. Following is the example,

  #Faster
  b1 = Benchmark.measure do 
    a = (0..100000).to_a
    index = 0
    while index <= 1000
      index+=1
    end
  end
  
  #Slower
  b2 = Benchmark.measure do 
    a = (0..100000).to_a
    a.each_with_index do |i,k|
    end
  end
  
  puts "While = #{b1}"
  
  puts "each_with_index = #{b2}"

• Directly make arrays with strings OR symbols

  %i{id email username uploaded_avatar_id} # creates [:id, :email, :username, :uploaded_avatar_id]
  %w{id email username uploaded_avatar_id} # creates ["id", "email", "username", "uploaded_avatar_id"]

• Use mass insert query with transaction when we have to create many rows, this is much faster.

  values = upload_ids.map{ |u| "(#{@post.id},#{u})" }.join(",") #Here, we need to insert multiple uploads for a same blog/message post. So, each row would have same post_id but different upload_id. upload_ids is an array here.
  
  PostUpload.transaction do #Start transaction
    PostUpload.delete_all(post_id: @post.id)
    if upload_ids.length > 0 #use insert query if we have at least one record
      PostUpload.exec_sql("INSERT INTO post_uploads (post_id, upload_id) VALUES #{values}")
    end
  end
  ```]

• https://www.coffeepowered.net/2009/01/23/mass-inserting-data-in-rails-without-killing-your-performance/

Updated it as a .md file for more readability.