Class: Chicago::Flow::Transformation

Inherits:
Object
  • Object
show all
Defined in:
lib/chicago/flow/transformation.rb

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Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(*args) ⇒ Transformation

Returns a new instance of Transformation.



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# File 'lib/chicago/flow/transformation.rb', line 6

def initialize(*args)
  stream, options = *args
  if stream.kind_of?(Hash)
    @stream = :default
    @options = stream
  else
    @stream = stream || :default
    @options = options || {}
  end
end

Class Attribute Details

.added_fields ⇒ Object (readonly)

Returns the value of attribute added_fields.



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# File 'lib/chicago/flow/transformation.rb', line 18

def added_fields
  @added_fields
end

.removed_fields ⇒ Object (readonly)

Returns the value of attribute removed_fields.



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# File 'lib/chicago/flow/transformation.rb', line 18

def removed_fields
  @removed_fields
end

Class Method Details

.adds_fields(*fields) ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 20

def adds_fields(*fields)
  @added_fields ||= []
  @added_fields += fields.flatten
end

.removes_fields(*fields) ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 25

def removes_fields(*fields)
  @removed_fields ||= []
  @removed_fields += fields.flatten
end

Instance Method Details

#added_fields ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 31

def added_fields
  self.class.added_fields
end

#applies_to_stream?(target_stream) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/chicago/flow/transformation.rb', line 59

def applies_to_stream?(target_stream)
  @stream == :all ||
    (target_stream.nil? && @stream == :default) ||
    target_stream == @stream
end

#downstream_fields(fields) ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 43

def downstream_fields(fields)
  ((fields - removed_fields) + added_fields).uniq
end

#flush ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 51

def flush
  []
end

#output_streams ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 55

def output_streams
  [:default]
end

#process(row) ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 47

def process(row)
  applies_to_stream?(row[STREAM]) ? process_row(row) : row
end

#removed_fields ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 35

def removed_fields
  self.class.removed_fields
end

#upstream_fields(fields) ⇒ Object 



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# File 'lib/chicago/flow/transformation.rb', line 39

def upstream_fields(fields)
  ((fields + removed_fields) - added_fields).uniq
end