Class: Mongoid::MapReduce::Formula::ArrayValues

Inherits:
Object
  • Object
show all
Includes:
Serialization
Defined in:
lib/mongoid/mapreduce/formula/array_values.rb

Instance Method Summary collapse

Methods included from Serialization

#serialize

Constructor Details

#initialize(fields, options = {}) ⇒ ArrayValues

Returns a new instance of ArrayValues.



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# File 'lib/mongoid/mapreduce/formula/array_values.rb', line 10

def initialize(fields, options={})
  options[:map_key] ||= :_id
  options[:count_type] ||= Integer
  options[:count_field] ||= :_count

  if fields.any?
    raise "Error: The Array Values formula does not take any fields. Please see documentation."
  end

  @field_name = options[:map_key]
  @field_type = options[:count_type]
  @count_field = options[:count_field]
end

Instance Method Details

#map ⇒ Object

Generate a map function Emits the value 1 for each value of the given array field

Returns String



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# File 'lib/mongoid/mapreduce/formula/array_values.rb', line 28

def map
  fn =  "function() { "
  fn <<   "this.#{@field_name.to_s}.forEach(function(value) { "
  fn <<     "emit(value, 1); "
  fn <<   "}); "
  fn << "}"
end

#process(collection) ⇒ Object

Process the results of a given collection

collection - the MongoDB collection returned from the map/reduce op

Returns Results



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# File 'lib/mongoid/mapreduce/formula/array_values.rb', line 53

def process(collection)
  return collection.inject(Results.new) do |h, k|
    key = k.values[0].to_s =~ /(^[-+]?[0-9]+$)|(\.0+)$/ ? Integer(k.values[0]) : Float(k.values[0])
    val = serialize(k.values[1].is_a?(String) ? k.values[1].split(',') : k.values[1], @field_type)
    h << Document.new(:_key_name => @field_name, :_key_value => key, key.to_s => val, @count_field => val)
  end
end

#reduce ⇒ Object

Generates a reduce function Adds the given values

Returns String



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# File 'lib/mongoid/mapreduce/formula/array_values.rb', line 40

def reduce
  fn =  "function(k, v) { "
  fn <<   "var result = 0; "
  fn <<   "v.forEach(function(val) { result += val; }); "
  fn <<   "return result; "
  fn << "}"
end