Class: Mongoid::MapReduce::Formula::AggregateFields

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

Instance Method Summary collapse

Methods included from Serialization

#serialize

Constructor Details

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

Returns a new instance of AggregateFields.



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

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

  @map_key = options[:map_key]
  @count_field = options[:count_field]
  @fields = fields
end

Instance Method Details

#map ⇒ Object

Generate a map function Emits the map key with an array of field values

Returns String



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# File 'lib/mongoid/mapreduce/formula/aggregate_fields.rb', line 23

def map
  fn =  "function() { "
  fn <<   "emit (this.#{@map_key}, [#{[1, @fields.collect{|k,v| "this.#{k}"}].flatten.join(", ")}]); "
  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/aggregate_fields.rb', line 50

def process(collection)
  return collection.inject(Results.new) do |h, k|
    key = k.values[0]
    vals = (k.values[1].is_a?(String) ? k.values[1].split(',') : k.values[1])
    doc = Document.new :_key_name => @map_key.to_s, :_key_value => key, @map_key => key, @count_field => vals[0].to_i
    @fields.each_with_index do |f, i|
      doc[f[0].to_sym] = serialize(vals[i + 1], f[1][:type])
    end
    h << doc
  end
end

#reduce ⇒ Object

Generates a reduce function Adds each value in the given array

Returns String



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# File 'lib/mongoid/mapreduce/formula/aggregate_fields.rb', line 33

def reduce
  fn =  "function(k, v) { "
  fn <<   "var results = [#{(["0"] * (@fields.length + 1)).flatten.join(", ")}]; "
  fn <<   "v.forEach(function(val) { "
  fn <<     "for(var i=0; i<= #{@fields.length}; i++) { "
  fn <<       "results[i] += (typeof val[i] == Boolean) ? (val[i] ? 1 : 0) : val[i] "
  fn <<     "} "
  fn <<   "}); "
  fn <<   "return results.toString(); "
  fn << "}"
end