Class: Amazon::Util::DataReader

Inherits:
Object
  • Object
show all
Defined in:
lib/amazon/util/data_reader.rb

Overview

DataReader is a class for loading in data files. It is used to support bulk file-based operations. DataReader supports a number of different formats:

  • YAML

  • Tabular

  • CSV

  • Java Properties

By default, DataReader assumes Tabular, but load and save both support your choice of format

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data = []) ⇒ DataReader

Returns a new instance of DataReader.



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# File 'lib/amazon/util/data_reader.rb', line 22

def initialize(data=[])
  @data = data
end

Instance Attribute Details

#data ⇒ Object

Returns the value of attribute data.



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# File 'lib/amazon/util/data_reader.rb', line 20

def data
  @data
end

Class Method Details

.load(filename, format = :Tabular) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 69

def self.load( filename, format=:Tabular )
  reader = DataReader.new()
  reader.load( filename, format )
end

.save(filename, data, format = :Tabular, force_headers = false) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 74

def self.save( filename, data, format=:Tabular, force_headers=false )
  reader = DataReader.new( data )
  reader.save( filename, format, force_headers )
end

Instance Method Details

#[](index) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 26

def [](index)
  return @data[index]
end

#[]=(index) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 30

def []=(index)
  return @data[index]
end

#load(filename, format = :Tabular) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 34

def load( filename, format=:Tabular )
  return {} unless File.exist? filename
  raw_data = File.read( filename )
  case format
  when :Tabular
    @data = parse_csv( raw_data, "\t" )
  when :YAML
    @data = YAML.load( raw_data ) || {}
  when :CSV
    @data = parse_csv( raw_data )
  when :Properties
    @data = parse_properties( raw_data )
  else
    raise "invalid format.  options are :Tabular, :YAML, :CSV, :Properties"
  end
end

#save(filename, format = :Tabular, force_headers = false) ⇒ Object 



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# File 'lib/amazon/util/data_reader.rb', line 51

def save( filename, format=:Tabular, force_headers=false )
  return if @data.nil? or @data.empty?
  existing = File.exist?( filename ) && File.size( filename ) > 0
  File.open( filename, 'a+' ) {|f| 
    f << case format
    when :Tabular
      generate_csv( @data, force_headers || !existing, "\t" )
    when :YAML
      YAML.dump( @data )
    when :CSV
      generate_csv( @data, force_headers || !existing )
    when :Properties
      generate_properties( @data )
    end
    f << "\n" # adding a newline on the end, so appending is happy
  }
end