diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/calculations.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 97 |
1 files changed, 47 insertions, 50 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 0f6015fa93..f45844a9ea 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -14,33 +14,34 @@ module ActiveRecord # Person.distinct.count(:age) # # => counts the number of different age values # - # If +count+ is used with +group+, it returns a Hash whose keys represent the aggregated column, + # If #count is used with {Relation#group}[rdoc-ref:QueryMethods#group], + # it returns a Hash whose keys represent the aggregated column, # and the values are the respective amounts: # # Person.group(:city).count # # => { 'Rome' => 5, 'Paris' => 3 } # - # If +count+ is used with +group+ for multiple columns, it returns a Hash whose + # If #count is used with {Relation#group}[rdoc-ref:QueryMethods#group] for multiple columns, it returns a Hash whose # keys are an array containing the individual values of each column and the value - # of each key would be the +count+. + # of each key would be the #count. # # Article.group(:status, :category).count # # => {["draft", "business"]=>10, ["draft", "technology"]=>4, # ["published", "business"]=>0, ["published", "technology"]=>2} # - # If +count+ is used with +select+, it will count the selected columns: + # If #count is used with {Relation#select}[rdoc-ref:QueryMethods#select], it will count the selected columns: # # Person.select(:age).count # # => counts the number of different age values # - # Note: not all valid +select+ expressions are valid +count+ expressions. The specifics differ + # Note: not all valid {Relation#select}[rdoc-ref:QueryMethods#select] expressions are valid #count expressions. The specifics differ # between databases. In invalid cases, an error from the database is thrown. def count(column_name = nil) calculate(:count, column_name) end # Calculates the average value on a given column. Returns +nil+ if there's - # no row. See +calculate+ for examples with options. + # no row. See #calculate for examples with options. # # Person.average(:age) # => 35.8 def average(column_name) @@ -49,7 +50,7 @@ module ActiveRecord # Calculates the minimum value on a given column. The value is returned # with the same data type of the column, or +nil+ if there's no row. See - # +calculate+ for examples with options. + # #calculate for examples with options. # # Person.minimum(:age) # => 7 def minimum(column_name) @@ -58,7 +59,7 @@ module ActiveRecord # Calculates the maximum value on a given column. The value is returned # with the same data type of the column, or +nil+ if there's no row. See - # +calculate+ for examples with options. + # #calculate for examples with options. # # Person.maximum(:age) # => 93 def maximum(column_name) @@ -66,46 +67,46 @@ module ActiveRecord end # Calculates the sum of values on a given column. The value is returned - # with the same data type of the column, 0 if there's no row. See - # +calculate+ for examples with options. + # with the same data type of the column, +0+ if there's no row. See + # #calculate for examples with options. # # Person.sum(:age) # => 4562 - def sum(*args) - return super if block_given? - calculate(:sum, *args) + def sum(column_name = nil, &block) + return super(&block) if block_given? + calculate(:sum, column_name) end - # This calculates aggregate values in the given column. Methods for count, sum, average, - # minimum, and maximum have been added as shortcuts. + # This calculates aggregate values in the given column. Methods for #count, #sum, #average, + # #minimum, and #maximum have been added as shortcuts. # - # There are two basic forms of output: + # Person.calculate(:count, :all) # The same as Person.count + # Person.average(:age) # SELECT AVG(age) FROM people... # - # * 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. + # # Selects the minimum age for any family without any minors + # Person.group(:last_name).having("min(age) > 17").minimum(:age) # - # * 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. + # Person.sum("2 * age") # - # values = Person.group('last_name').maximum(:age) - # puts values["Drake"] - # # => 43 + # There are two basic forms of output: # - # drake = Family.find_by(last_name: 'Drake') - # values = Person.group(:family).maximum(:age) # Person belongs_to :family - # puts values[drake] - # # => 43 + # * 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. # - # values.each do |family, max_age| - # ... - # end + # * 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. # - # Person.calculate(:count, :all) # The same as Person.count - # Person.average(:age) # SELECT AVG(age) FROM people... + # values = Person.group('last_name').maximum(:age) + # puts values["Drake"] + # # => 43 # - # # Selects the minimum age for any family without any minors - # Person.group(:last_name).having("min(age) > 17").minimum(:age) + # drake = Family.find_by(last_name: 'Drake') + # values = Person.group(:family).maximum(:age) # Person belongs_to :family + # puts values[drake] + # # => 43 # - # Person.sum("2 * age") + # values.each do |family, max_age| + # ... + # end def calculate(operation, column_name) if column_name.is_a?(Symbol) && attribute_alias?(column_name) column_name = attribute_alias(column_name) @@ -118,7 +119,7 @@ module ActiveRecord end end - # Use <tt>pluck</tt> as a shortcut to select one or more attributes without + # Use #pluck as a shortcut to select one or more attributes without # loading a bunch of records just to grab the attributes you want. # # Person.pluck(:name) @@ -127,7 +128,7 @@ module ActiveRecord # # Person.all.map(&:name) # - # Pluck returns an <tt>Array</tt> of attribute values type-casted to match + # Pluck returns an Array of attribute values type-casted to match # the plucked column names, if they can be deduced. Plucking an SQL fragment # returns String values by default. # @@ -151,7 +152,7 @@ module ActiveRecord # # SELECT DATEDIFF(updated_at, created_at) FROM people # # => ['0', '27761', '173'] # - # See also +ids+. + # See also #ids. # def pluck(*column_names) column_names.map! do |column_name| @@ -218,6 +219,8 @@ module ActiveRecord end def aggregate_column(column_name) + return column_name if Arel::Expressions === column_name + if @klass.column_names.include?(column_name.to_s) Arel::Attribute.new(@klass.unscoped.table, column_name) else @@ -272,15 +275,10 @@ module ActiveRecord else group_fields = group_attrs end + group_fields = arel_columns(group_fields) - group_aliases = group_fields.map { |field| - column_alias_for(field) - } - group_columns = group_aliases.zip(group_fields).map { |aliaz,field| - [aliaz, field] - } - - group = group_fields + group_aliases = group_fields.map { |field| column_alias_for(field) } + group_columns = group_aliases.zip(group_fields) if operation == 'count' && column_name == :all aggregate_alias = 'count_all' @@ -296,7 +294,7 @@ module ActiveRecord ] select_values += select_values unless having_clause.empty? - select_values.concat group_fields.zip(group_aliases).map { |field,aliaz| + select_values.concat group_columns.map { |aliaz, field| if field.respond_to?(:as) field.as(aliaz) else @@ -305,7 +303,7 @@ module ActiveRecord } relation = except(:group) - relation.group_values = group + relation.group_values = group_fields relation.select_values = select_values calculated_data = @klass.connection.select_all(relation, nil, relation.bound_attributes) @@ -338,7 +336,6 @@ module ActiveRecord # column_alias_for("sum(id)") # => "sum_id" # column_alias_for("count(distinct users.id)") # => "count_distinct_users_id" # column_alias_for("count(*)") # => "count_all" - # column_alias_for("count", "id") # => "count_id" def column_alias_for(keys) if keys.respond_to? :name keys = "#{keys.relation.name}.#{keys.name}" @@ -367,9 +364,9 @@ module ActiveRecord end end - # TODO: refactor to allow non-string `select_values` (eg. Arel nodes). def select_for_count if select_values.present? + return select_values.first if select_values.one? select_values.join(", ") else :all |