diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/calculations.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 188 |
1 files changed, 107 insertions, 81 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index a679c444cf..c1842b1a96 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -6,32 +6,30 @@ module ActiveRecord # Count operates using three different approaches. # # * Count all: By not passing any parameters to count, it will return a count of all the rows for the model. - # * Count using column: By passing a column name to count, it will return a count of all the - # rows for the model with supplied column present + # * Count using column: By passing a column name to count, it will return a count of all the + # rows for the model with supplied column present. # * Count using options will find the row count matched by the options used. # # The third approach, count using options, accepts an option hash as the only parameter. The options are: # - # * <tt>:conditions</tt>: An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. + # * <tt>:conditions</tt>: An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. # See conditions in the intro to ActiveRecord::Base. - # * <tt>:joins</tt>: Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (rarely needed) - # or named associations in the same form used for the <tt>:include</tt> option, which will - # perform an INNER JOIN on the associated table(s). - # If the value is a string, then the records will be returned read-only since they will have - # attributes that do not correspond to the table's columns. + # * <tt>:joins</tt>: Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" + # (rarely needed) or named associations in the same form used for the <tt>:include</tt> option, which will + # perform an INNER JOIN on the associated table(s). If the value is a string, then the records + # will be returned read-only since they will have attributes that do not correspond to the table's columns. # Pass <tt>:readonly => false</tt> to override. - # * <tt>:include</tt>: Named associations that should be loaded alongside using LEFT OUTER JOINs. - # The symbols named refer to already defined associations. When using named associations, count + # * <tt>:include</tt>: Named associations that should be loaded alongside using LEFT OUTER JOINs. + # The symbols named refer to already defined associations. When using named associations, count # returns the number of DISTINCT items for the model you're counting. # See eager loading under Associations. # * <tt>:order</tt>: An SQL fragment like "created_at DESC, name" (really only used with GROUP BY calculations). # * <tt>:group</tt>: An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause. - # * <tt>:select</tt>: By default, this is * as in SELECT * FROM, but can be changed if you, for example, - # want to do a join but not - # include the joined columns. - # * <tt>:distinct</tt>: Set this to true to make this a distinct calculation, such as + # * <tt>:select</tt>: By default, this is * as in SELECT * FROM, but can be changed if you, for example, + # want to do a join but not include the joined columns. + # * <tt>:distinct</tt>: Set this to true to make this a distinct calculation, such as # SELECT COUNT(DISTINCT posts.id) ... - # * <tt>:from</tt> - By default, this is the table name of the class, but can be changed to an + # * <tt>:from</tt> - By default, this is the table name of the class, but can be changed to an # alternate table name (or even the name of a database view). # # Examples for counting all: @@ -44,16 +42,16 @@ module ActiveRecord # Person.count(:conditions => "age > 26") # # # because of the named association, it finds the DISTINCT count using LEFT OUTER JOIN. - # Person.count(:conditions => "age > 26 AND job.salary > 60000", :include => :job) + # Person.count(:conditions => "age > 26 AND job.salary > 60000", :include => :job) # # # finds the number of rows matching the conditions and joins. - # Person.count(:conditions => "age > 26 AND job.salary > 60000", - # :joins => "LEFT JOIN jobs on jobs.person_id = person.id") + # Person.count(:conditions => "age > 26 AND job.salary > 60000", + # :joins => "LEFT JOIN jobs on jobs.person_id = person.id") # # Person.count('id', :conditions => "age > 26") # Performs a COUNT(id) # Person.count(:all, :conditions => "age > 26") # Performs a COUNT(*) (:all is an alias for '*') # - # Note: <tt>Person.count(:all)</tt> will not work because it will use <tt>:all</tt> as the condition. + # Note: <tt>Person.count(:all)</tt> will not work because it will use <tt>:all</tt> as the condition. # Use Person.count instead. def count(column_name = nil, options = {}) column_name, options = nil, column_name if column_name.is_a?(Hash) @@ -95,14 +93,14 @@ module ActiveRecord calculate(:sum, column_name, options) end - # This calculates aggregate values in the given column. Methods for count, sum, average, - # minimum, and maximum have been added as shortcuts. Options such as <tt>:conditions</tt>, + # This calculates aggregate values in the given column. Methods for count, sum, average, + # minimum, and maximum have been added as shortcuts. Options such as <tt>:conditions</tt>, # <tt>:order</tt>, <tt>:group</tt>, <tt>:having</tt>, and <tt>:joins</tt> can be passed to customize the query. # # There are two basic forms of output: - # * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float + # * Single aggregate value: The single value is type cast to Fixnum for COUNT, Float # for AVG, and the given column's type for everything else. - # * Grouped values: This returns an ordered hash of the values and groups them by the + # * Grouped values: This returns an ordered hash of the values and groups them by the # <tt>:group</tt> option. It takes either a column name, or the name of a belongs_to association. # # values = Person.maximum(:age, :group => 'last_name') @@ -119,29 +117,29 @@ module ActiveRecord # end # # Options: - # * <tt>:conditions</tt> - An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. + # * <tt>:conditions</tt> - An SQL fragment like "administrator = 1" or [ "user_name = ?", username ]. # See conditions in the intro to ActiveRecord::Base. - # * <tt>:include</tt>: Eager loading, see Associations for details. Since calculations don't load anything, + # * <tt>:include</tt>: Eager loading, see Associations for details. Since calculations don't load anything, # the purpose of this is to access fields on joined tables in your conditions, order, or group clauses. - # * <tt>:joins</tt> - An SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id". + # * <tt>:joins</tt> - An SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id". # (Rarely needed). - # The records will be returned read-only since they will have attributes that do not correspond to the + # The records will be returned read-only since they will have attributes that do not correspond to the # table's columns. # * <tt>:order</tt> - An SQL fragment like "created_at DESC, name" (really only used with GROUP BY calculations). # * <tt>:group</tt> - An attribute name by which the result should be grouped. Uses the GROUP BY SQL-clause. - # * <tt>:select</tt> - By default, this is * as in SELECT * FROM, but can be changed if you for example + # * <tt>:select</tt> - By default, this is * as in SELECT * FROM, but can be changed if you for example # want to do a join, but not include the joined columns. - # * <tt>:distinct</tt> - Set this to true to make this a distinct calculation, such as + # * <tt>:distinct</tt> - Set this to true to make this a distinct calculation, such as # SELECT COUNT(DISTINCT posts.id) ... # # Examples: # Person.calculate(:count, :all) # The same as Person.count # Person.average(:age) # SELECT AVG(age) FROM people... - # Person.minimum(:age, :conditions => ['last_name != ?', 'Drake']) # Selects the minimum age for + # Person.minimum(:age, :conditions => ['last_name != ?', 'Drake']) # Selects the minimum age for # # everyone with a last name other than 'Drake' # # # Selects the minimum age for any family without any minors - # Person.minimum(:age, :having => 'min(age) > 17', :group => :last_name) + # Person.minimum(:age, :having => 'min(age) > 17', :group => :last_name) # # Person.sum("2 * age") def calculate(operation, column_name, options = {}) @@ -163,80 +161,112 @@ module ActiveRecord def perform_calculation(operation, column_name, options = {}) operation = operation.to_s.downcase + distinct = nil + if operation == "count" column_name ||= (select_for_count || :all) - joins = arel.joins(arel) - if joins.present? && joins =~ /LEFT OUTER/i + unless arel.ast.grep(Arel::Nodes::OuterJoin).empty? distinct = true - column_name = @klass.primary_key if column_name == :all + column_name = primary_key if column_name == :all end - distinct = nil if column_name.to_s =~ /\s*DISTINCT\s+/i - distinct ||= options[:distinct] - else - distinct = nil + distinct = nil if column_name =~ /\s*DISTINCT\s+/i end distinct = options[:distinct] || distinct - column_name = :all if column_name.blank? && operation == "count" if @group_values.any? - return execute_grouped_calculation(operation, column_name) + execute_grouped_calculation(operation, column_name, distinct) else - return execute_simple_calculation(operation, column_name, distinct) + execute_simple_calculation(operation, column_name, distinct) end end - def execute_simple_calculation(operation, column_name, distinct) #:nodoc: - column = if @klass.column_names.include?(column_name.to_s) - Arel::Attribute.new(@klass.unscoped, column_name) + def aggregate_column(column_name) + if @klass.column_names.include?(column_name.to_s) + Arel::Attribute.new(@klass.unscoped.table, column_name) else - Arel::SqlLiteral.new(column_name == :all ? "*" : column_name.to_s) + Arel.sql(column_name == :all ? "*" : column_name.to_s) end + end - # Postgresql doesn't like ORDER BY when there are no GROUP BY - relation = except(:order).select(operation == 'count' ? column.count(distinct) : column.send(operation)) - type_cast_calculated_value(@klass.connection.select_value(relation.to_sql), column_for(column_name), operation) + def operation_over_aggregate_column(column, operation, distinct) + operation == 'count' ? column.count(distinct) : column.send(operation) end - def execute_grouped_calculation(operation, column_name) #:nodoc: - group_attr = @group_values.first - association = @klass.reflect_on_association(group_attr.to_sym) - associated = association && association.macro == :belongs_to # only count belongs_to associations - group_field = associated ? association.primary_key_name : group_attr - group_alias = column_alias_for(group_field) - group_column = column_for(group_field) + def execute_simple_calculation(operation, column_name, distinct) #:nodoc: + column = aggregate_column(column_name) - group = @klass.connection.adapter_name == 'FrontBase' ? group_alias : group_field + # Postgresql doesn't like ORDER BY when there are no GROUP BY + relation = except(:order) + select_value = operation_over_aggregate_column(column, operation, distinct) + + relation.select_values = [select_value] - aggregate_alias = column_alias_for(operation, column_name) + query_builder = relation.arel - select_statement = if operation == 'count' && column_name == :all - "COUNT(*) AS count_all" + if operation == "count" + limit = relation.limit_value + offset = relation.offset_value + + unless limit && offset + query_builder.limit = nil + query_builder.offset = nil + end + end + + type_cast_calculated_value(@klass.connection.select_value(query_builder.to_sql), column_for(column_name), operation) + end + + def execute_grouped_calculation(operation, column_name, distinct) #:nodoc: + group_attr = @group_values + association = @klass.reflect_on_association(group_attr.first.to_sym) + associated = group_attr.size == 1 && association && association.macro == :belongs_to # only count belongs_to associations + group_fields = Array(associated ? association.foreign_key : group_attr) + group_aliases = group_fields.map { |field| column_alias_for(field) } + group_columns = group_aliases.zip(group_fields).map { |aliaz,field| + [aliaz, column_for(field)] + } + + group = @klass.connection.adapter_name == 'FrontBase' ? group_aliases : group_fields + + if operation == 'count' && column_name == :all + aggregate_alias = 'count_all' else - Arel::Attribute.new(@klass.unscoped, column_name).send(operation).as(aggregate_alias).to_sql + aggregate_alias = column_alias_for(operation, column_name) end - select_statement << ", #{group_field} AS #{group_alias}" + select_values = [ + operation_over_aggregate_column( + aggregate_column(column_name), + operation, + distinct).as(aggregate_alias) + ] + + select_values.concat group_fields.zip(group_aliases).map { |field,aliaz| + "#{field} AS #{aliaz}" + } - relation = except(:group).select(select_statement).group(group) + relation = except(:group).group(group.join(',')) + relation.select_values = select_values calculated_data = @klass.connection.select_all(relation.to_sql) if association - key_ids = calculated_data.collect { |row| row[group_alias] } + key_ids = calculated_data.collect { |row| row[group_aliases.first] } key_records = association.klass.base_class.find(key_ids) - key_records = key_records.inject({}) { |hsh, r| hsh.merge(r.id => r) } + key_records = Hash[key_records.map { |r| [r.id, r] }] end - calculated_data.inject(ActiveSupport::OrderedHash.new) do |all, row| - key = type_cast_calculated_value(row[group_alias], group_column) - key = key_records[key] if associated - value = row[aggregate_alias] - all[key] = type_cast_calculated_value(value, column_for(column_name), operation) - all - end + ActiveSupport::OrderedHash[calculated_data.map do |row| + key = group_columns.map { |aliaz, column| + type_cast_calculated_value(row[aliaz], column) + } + key = key.first if key.size == 1 + key = key_records[key] if associated + [key, type_cast_calculated_value(row[aggregate_alias], column_for(column_name), operation)] + end] end # Converts the given keys to the value that the database adapter returns as @@ -264,15 +294,11 @@ module ActiveRecord end def type_cast_calculated_value(value, column, operation = nil) - if value.is_a?(String) || value.nil? - case operation - when 'count' then value.to_i - when 'sum' then type_cast_using_column(value || '0', column) - when 'average' then value.try(:to_d) - else type_cast_using_column(value, column) - end - else - value + case operation + when 'count' then value.to_i + when 'sum' then type_cast_using_column(value || '0', column) + when 'average' then value.respond_to?(:to_d) ? value.to_d : value + else type_cast_using_column(value, column) end end @@ -282,7 +308,7 @@ module ActiveRecord def select_for_count if @select_values.present? - select = @select_values.join(", ") + select = @select_values.join(", ") select if select !~ /(,|\*)/ end end |