diff options
Diffstat (limited to 'activerecord/lib/active_record/relation/calculations.rb')
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 31 |
1 files changed, 16 insertions, 15 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index ee078102ca..16d5774fec 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) @@ -66,8 +67,8 @@ 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(column_name = nil, &block) @@ -75,8 +76,8 @@ module ActiveRecord 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. # # Person.calculate(:count, :all) # The same as Person.count # Person.average(:age) # SELECT AVG(age) FROM people... @@ -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| |