Class: Prosperity::Aggregate::Sql

Inherits:
Base
  • Object
show all
Defined in:
lib/prosperity/aggregate/sql.rb

Instance Method Summary collapse

Constructor Details

#initialize(sql) ⇒ Sql

Returns a new instance of Sql.



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# File 'lib/prosperity/aggregate/sql.rb', line 3

def initialize(sql)
  @sql = sql
end

Instance Method Details

#apply(scope, group_by_sql: nil) ⇒ Object 



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# File 'lib/prosperity/aggregate/sql.rb', line 11

def apply(scope, group_by_sql: nil)
  # This is pretty hacky.. this assumes that the aggregate SQL can be
  # inserted into this query and provide a valid query. We also leave it to
  # the extractor to set this value if needed
  if group_by_sql
    s = scope.select("#{group_by_sql} AS bucket, #{to_sql}")
    s.inject({}) {|accum, el|
      attr = el.attributes.keys.select do |key|
        !%w(id bucket).include?(key)
      end.first
      accum[el["bucket"]] = el.attributes[attr].to_f
      accum
    }
  else
    s = scope.select(to_sql)

    # This isn't a group by, we should return a single value rather than a
    # scope
    if s.group_values.empty?
      raise "Unexpected size" unless s.to_a.size == 1
      record = s.first
      # Assumes that the select statement as a single value attribute
      # AR always add id, so get rid of that
      value_attr = record.attributes.keys.first { |a| a != "id" }
      record.attributes[value_attr]
    else
      s
    end
  end
end

#to_sql ⇒ Object 



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# File 'lib/prosperity/aggregate/sql.rb', line 7

def to_sql
  @sql
end