Module: CompositePrimaryKeys::ActiveRecord::Calculations

Included in:
CompositeRelation
Defined in:
lib/composite_primary_keys/relation/calculations.rb

Instance Method Summary collapse

Instance Method Details

#aggregate_column(column_name) ⇒ Object 



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# File 'lib/composite_primary_keys/relation/calculations.rb', line 4

def aggregate_column(column_name)
  # CPK
  if column_name.kind_of?(Array)
    column_name.map do |column|
      Arel::Attribute.new(@klass.unscoped.table, column)
    end
  elsif @klass.column_names.include?(column_name.to_s)
    Arel::Attribute.new(@klass.unscoped.table, column_name)
  else
    Arel.sql(column_name == :all ? "*" : column_name.to_s)
  end
end

#build_count_subquery(relation, column_name, distinct) ⇒ Object 



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# File 'lib/composite_primary_keys/relation/calculations.rb', line 57

def build_count_subquery(relation, column_name, distinct)
  relation.select_values = [
      if column_name == :all
        distinct ? table[Arel.star] : Arel.sql(::ActiveRecord::FinderMethods::ONE_AS_ONE)
      # CPK
      elsif column_name.is_a?(Array)
        relation.select_values = column_name.map do |column|
          Arel::Attribute.new(@klass.unscoped.table, column)
        end
      else
        column_alias = Arel.sql("count_column")
        aggregate_column(column_name).as(column_alias)
      end
  ]

  subquery = relation.arel.as(Arel.sql("subquery_for_count"))
  select_value = operation_over_aggregate_column(column_alias || Arel.star, "count", false)

  Arel::SelectManager.new(subquery).project(select_value)
end

#execute_simple_calculation(operation, column_name, distinct) ⇒ Object

:nodoc:



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# File 'lib/composite_primary_keys/relation/calculations.rb', line 17

def execute_simple_calculation(operation, column_name, distinct) #:nodoc:
  column_alias = column_name

  # CPK
  # if operation == "count" && has_limit_or_offset?
  #   # Shortcut when limit is zero.
  #   return 0 if limit_value == 0
  #
  #   query_builder = build_count_subquery(spawn, column_name, distinct)
  if operation == "count"
    relation = unscope(:order)
    query_builder = build_count_subquery(relation, column_name, distinct)
  else
    # PostgreSQL doesn't like ORDER BY when there are no GROUP BY
    relation = unscope(:order).distinct!(false)

    column = aggregate_column(column_name)

    select_value = operation_over_aggregate_column(column, operation, distinct)
    if operation == "sum" && distinct
      select_value.distinct = true
    end

    column_alias = select_value.alias
    column_alias ||= @klass.connection.column_name_for_operation(operation, select_value)
    relation.select_values = [select_value]

    query_builder = relation.arel
  end

  result = skip_query_cache_if_necessary { @klass.connection.select_all(query_builder, nil) }
  row    = result.first
  value  = row && row.values.first
  type   = result.column_types.fetch(column_alias) do
    type_for(column_name)
  end

  type_cast_calculated_value(value, type, operation)
end