diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/calculations.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 260 |
1 files changed, 143 insertions, 117 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 50239f7cb2..7c43d844d0 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -1,61 +1,30 @@ -require 'active_support/core_ext/object/blank' require 'active_support/core_ext/object/try' module ActiveRecord module Calculations - # 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 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 ]. - # 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. - # 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 - # 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 - # SELECT COUNT(DISTINCT posts.id) ... - # * <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: - # Person.count # returns the total count of all people - # - # Examples for counting by column: - # Person.count(:age) # returns the total count of all people whose age is present in database - # - # Examples for count with options: - # 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) - # - # # 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('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. - # Use Person.count instead. + # Count the records. + # + # Person.count + # # => the total count of all people + # + # Person.count(:age) + # # => returns the total count of all people whose age is present in database + # + # Person.count(:all) + # # => performs a COUNT(*) (:all is an alias for '*') + # + # Person.count(:age, distinct: true) + # # => counts the number of different age values + # + # Person.where("age > 26").count { |person| person.gender == 'female' } + # # => queries people where "age > 26" then count the loaded results filtering by gender def count(column_name = nil, options = {}) - column_name, options = nil, column_name if column_name.is_a?(Hash) - calculate(:count, column_name, options) + if block_given? + self.to_a.count { |item| yield item } + else + column_name, options = nil, column_name if column_name.is_a?(Hash) + calculate(:count, column_name, options) + end end # Calculates the average value on a given column. Returns +nil+ if there's @@ -89,30 +58,35 @@ module ActiveRecord # +calculate+ for examples with options. # # Person.sum('age') # => 4562 + # # => returns the total sum of all people's age + # + # Person.where('age > 100').sum { |person| person.age - 100 } + # # queries people where "age > 100" then perform a sum calculation with the block returns def sum(*args) if block_given? - self.to_a.sum(*args) {|*block_args| yield(*block_args)} + self.to_a.sum(*args) { |item| yield item } else calculate(:sum, *args) end 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>, - # <tt>:order</tt>, <tt>:group</tt>, <tt>:having</tt>, and <tt>:joins</tt> can be passed to customize the query. + # minimum, and maximum have been added as shortcuts. # # There are two basic forms of output: + # # * 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 - # <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') + # * Grouped values: This returns an ordered hash of the values and groups them. It + # takes either a column name, or the name of a belongs_to association. + # + # values = Person.group('last_name').maximum(:age) # puts values["Drake"] # => 43 # # drake = Family.find_by_last_name('Drake') - # values = Person.maximum(:age, :group => :family) # Person belongs_to :family + # values = Person.group(:family).maximum(:age) # Person belongs_to :family # puts values[drake] # => 43 # @@ -120,73 +94,113 @@ module ActiveRecord # ... # end # - # Options: - # * <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, - # 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". - # (Rarely needed). - # 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 - # 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) ... - # # 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 - # # 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.group(:last_name).having("min(age) > 17").minimum(:age) # # Person.sum("2 * age") def calculate(operation, column_name, options = {}) - if options.except(:distinct).present? - apply_finder_options(options.except(:distinct)).calculate(operation, column_name, :distinct => options[:distinct]) - else - relation = with_default_scope + relation = with_default_scope - if relation.equal?(self) - if eager_loading? || (includes_values.present? && references_eager_loaded_tables?) - construct_relation_for_association_calculations.calculate(operation, column_name, options) - else - perform_calculation(operation, column_name, options) - end + if relation.equal?(self) + if has_include?(column_name) + construct_relation_for_association_calculations.calculate(operation, column_name, options) else - relation.calculate(operation, column_name, options) + perform_calculation(operation, column_name, options) end + else + relation.calculate(operation, column_name, options) end rescue ThrowResult 0 end - # This method is designed to perform select by a single column as direct SQL query - # Returns <tt>Array</tt> with values of the specified column name - # The values has same data type as column. + # Use <tt>pluck</tt> as a shortcut to select a single attribute without + # loading a bunch of records just to grab one attribute you want. + # + # Person.pluck(:name) + # + # instead of + # + # Person.all.map(&:name) + # + # Pluck returns an <tt>Array</tt> of attribute values type-casted to match + # the plucked column name, if it can be deduced. Plucking an SQL fragment + # returns String values by default. # # Examples: # - # Person.pluck(:id) # SELECT people.id FROM people - # Person.uniq.pluck(:role) # SELECT DISTINCT role FROM people - # Person.where(:confirmed => true).limit(5).pluck(:id) + # Person.pluck(:id) + # # SELECT people.id FROM people + # # => [1, 2, 3] + # + # Person.pluck(:id, :name) + # # SELECT people.id, people.name FROM people + # # => [[1, 'David'], [2, 'Jeremy'], [3, 'Jose']] + # + # Person.uniq.pluck(:role) + # # SELECT DISTINCT role FROM people + # # => ['admin', 'member', 'guest'] + # + # Person.where(:age => 21).limit(5).pluck(:id) + # # SELECT people.id FROM people WHERE people.age = 21 LIMIT 5 + # # => [2, 3] + # + # Person.pluck('DATEDIFF(updated_at, created_at)') + # # SELECT DATEDIFF(updated_at, created_at) FROM people + # # => ['0', '27761', '173'] # - def pluck(column_name) - if column_name.is_a?(Symbol) && column_names.include?(column_name.to_s) - column_name = "#{table_name}.#{column_name}" + def pluck(*column_names) + column_names.map! do |column_name| + if column_name.is_a?(Symbol) && self.column_names.include?(column_name.to_s) + "#{connection.quote_table_name(table_name)}.#{connection.quote_column_name(column_name)}" + else + column_name + end end - klass.connection.select_all(select(column_name).arel).map! do |attributes| - klass.type_cast_attribute(attributes.keys.first, klass.initialize_attributes(attributes)) + + if has_include?(column_names.first) + construct_relation_for_association_calculations.pluck(*column_names) + else + result = klass.connection.select_all(select(column_names).arel, nil, bind_values) + columns = result.columns.map do |key| + klass.column_types.fetch(key) { + result.column_types.fetch(key) { + Class.new { def type_cast(v); v; end }.new + } + } + end + + result = result.map do |attributes| + values = klass.initialize_attributes(attributes).values + + columns.zip(values).map do |column, value| + column.type_cast(value) + end + end + columns.one? ? result.map!(&:first) : result end end + # Pluck all the ID's for the relation using the table's primary key + # + # Examples: + # + # Person.ids # SELECT people.id FROM people + # Person.joins(:companies).ids # SELECT people.id FROM people INNER JOIN companies ON companies.person_id = people.id + def ids + pluck primary_key + end + private + def has_include?(column_name) + eager_loading? || (includes_values.present? && (column_name || references_eager_loaded_tables?)) + end + def perform_calculation(operation, column_name, options = {}) operation = operation.to_s.downcase @@ -204,7 +218,7 @@ module ActiveRecord distinct = nil if column_name =~ /\s*DISTINCT\s+/i end - if @group_values.any? + if group_values.any? execute_grouped_calculation(operation, column_name, distinct) else execute_simple_calculation(operation, column_name, distinct) @@ -242,14 +256,21 @@ module ActiveRecord query_builder = relation.arel end - type_cast_calculated_value(@klass.connection.select_value(query_builder), column_for(column_name), operation) + result = @klass.connection.select_value(query_builder, nil, relation.bind_values) + type_cast_calculated_value(result, 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_attrs = group_values + + if group_attrs.first.respond_to?(:to_sym) + association = @klass.reflect_on_association(group_attrs.first.to_sym) + associated = group_attrs.size == 1 && association && association.macro == :belongs_to # only count belongs_to associations + group_fields = Array(associated ? association.foreign_key : group_attrs) + else + group_fields = group_attrs + end + group_aliases = group_fields.map { |field| column_alias_for(field) } group_columns = group_aliases.zip(group_fields).map { |aliaz,field| [aliaz, column_for(field)] @@ -269,16 +290,20 @@ module ActiveRecord operation, distinct).as(aggregate_alias) ] - select_values += @select_values unless @having_values.empty? + select_values += select_values unless having_values.empty? select_values.concat group_fields.zip(group_aliases).map { |field,aliaz| - "#{field} AS #{aliaz}" + if field.respond_to?(:as) + field.as(aliaz) + else + "#{field} AS #{aliaz}" + end } - relation = except(:group).group(group.join(',')) + relation = except(:group).group(group) relation.select_values = select_values - calculated_data = @klass.connection.select_all(relation) + calculated_data = @klass.connection.select_all(relation, nil, bind_values) if association key_ids = calculated_data.collect { |row| row[group_aliases.first] } @@ -286,11 +311,11 @@ module ActiveRecord key_records = Hash[key_records.map { |r| [r.id, r] }] end - ActiveSupport::OrderedHash[calculated_data.map do |row| - key = group_columns.map { |aliaz, column| + Hash[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.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] @@ -305,6 +330,7 @@ module ActiveRecord # column_alias_for("count(*)") # => "count_all" # column_alias_for("count", "id") # => "count_id" def column_alias_for(*keys) + keys.map! {|k| k.respond_to?(:to_sql) ? k.to_sql : k} table_name = keys.join(' ') table_name.downcase! table_name.gsub!(/\*/, 'all') @@ -316,7 +342,7 @@ module ActiveRecord end def column_for(field) - field_name = field.to_s.split('.').last + field_name = field.respond_to?(:name) ? field.name.to_s : field.to_s.split('.').last @klass.columns.detect { |c| c.name.to_s == field_name } end @@ -334,8 +360,8 @@ module ActiveRecord end def select_for_count - if @select_values.present? - select = @select_values.join(", ") + if select_values.present? + select = select_values.join(", ") select if select !~ /[,*]/ end end |