Module: AbacusCount::Calculations

Defined in:
lib/abacus_count/calculations.rb

Instance Method Summary collapse

Instance Method Details

#build_subquery(relation, aliaz) ⇒ Object 



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# File 'lib/abacus_count/calculations.rb', line 29

def build_subquery(relation, aliaz)
  # Since arel 2.1.1 it will look like
  # relation.arel.as(subquery_alias)
  Arel::Nodes::As.new(Arel::Nodes::Grouping.new(relation.arel.ast), Arel::Nodes::SqlLiteral.new(aliaz))
end

#execute_grouped_calculation(operation, column_name, distinct) ⇒ Object 



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# File 'lib/abacus_count/calculations.rb', line 7

def execute_grouped_calculation(operation, column_name, distinct)
  execute_subquery_calculation(operation, column_name, distinct)
end

#execute_simple_calculation(operation, column_name, distinct) ⇒ Object 



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# File 'lib/abacus_count/calculations.rb', line 3

def execute_simple_calculation(operation, column_name, distinct)
  execute_subquery_calculation(operation, column_name, distinct)
end

#execute_subquery_calculation(operation, column_name, distinct) ⇒ Object 



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# File 'lib/abacus_count/calculations.rb', line 11

def execute_subquery_calculation(operation, column_name, distinct)
  relation = reorder(nil)

  column_alias = Arel.sql("#{operation}_column")
  subquery_alias = Arel.sql("subquery_for_#{operation}")

  aliased_column = aggregate_column(column_name == :all ? 1 : column_name).as(column_alias)
  relation.select_values += [aliased_column]

  subquery = build_subquery(relation, subquery_alias)

  sm = Arel::SelectManager.new relation.engine
  select_value = operation_over_aggregate_column(column_alias, operation, distinct)
  query_builder = sm.project(select_value).from(subquery)

  type_cast_calculated_value(@klass.connection.select_value(query_builder.to_sql), column_for(column_name), operation)
end