Method: Og::SqlStore#aggregate

Defined in:
lib/og/store/sql.rb

#aggregate(term = 'COUNT(*)', options = {}) ⇒ Object Also known as: calculate

Perform an aggregation or calculation over query results. This low level method is used by the Entity calculation / aggregation methods.

Options

:field = the return type.

Example

calculate ‘COUNT(*)’ calculate ‘MIN(age)’ calculate ‘SUM(age)’, :group => :name



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# File 'lib/og/store/sql.rb', line 280

def aggregate(term = 'COUNT(*)', options = {})
  # Leave this .dup here, causes problems because options are changed
  options = options.dup
  
  klass = options[:class]
  field = options[:field]
  
  # Rename search term, SQL92 but _not_ SQL89 compatible
  options.update(:select => "#{term} AS #{term[/^\w+/]}")
  
  unless options[:group] || options[:group_by]
    options.delete(:order)
    options.delete(:order_by)
  end
  
  sql = resolve_options(klass, options)
  
  if anno = klass.ann[field]
    return_type = anno.class
  end
  return_type ||= Integer
  
  if options[:group] || options[:group_by]
    # This is an aggregation, so return the calculated values
    # as an array.
    values = []
    res = query(sql)
    res.each_row do |row, idx|
      values << type_cast(return_type, row[0])
    end
    return values
  else
    return type_cast(return_type, query(sql).first_value)
  end
  
end