diff options
Diffstat (limited to 'activerecord')
| -rw-r--r-- | activerecord/lib/active_record/associations/collection_proxy.rb | 16 | ||||
| -rw-r--r-- | activerecord/lib/active_record/relation/calculations.rb | 6 |
2 files changed, 16 insertions, 6 deletions
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb index 6e05af894e..7f9628499c 100644 --- a/activerecord/lib/active_record/associations/collection_proxy.rb +++ b/activerecord/lib/active_record/associations/collection_proxy.rb @@ -672,7 +672,11 @@ module ActiveRecord end # Returns the size of the collection. If the collection hasn't been loaded, - # it executes a <tt>SELECT COUNT(*)</tt> query. + # it executes a <tt>SELECT COUNT(*)</tt> query. Else it calls <tt>collection.size</tt>. + # + # If the collection has been already loaded +size+ and +length+ are + # equivalent. If not and you are going to need the records anyway + # +length+ will take one less query. Otherwise +size+ is more efficient. # # class Person < ActiveRecord::Base # has_many :pets @@ -697,7 +701,8 @@ module ActiveRecord # Returns the size of the collection calling +size+ on the target. # If the collection has been already loaded, +length+ and +size+ are - # equivalent. + # equivalent. If not and you are going to need the records anyway this + # method will take one less query. Otherwise +size+ is more efficient. # # class Person < ActiveRecord::Base # has_many :pets @@ -718,7 +723,12 @@ module ActiveRecord @association.length end - # Returns +true+ if the collection is empty. + # Returns +true+ if the collection is empty. If the collection has been + # loaded or the <tt>:counter_sql</tt> option is provided, it is equivalent + # to <tt>collection.size.zero?</tt>. If the collection has not been loaded, + # it is equivalent to <tt>collection.exists?</tt>. If the collection has + # not already been loaded and you are going to fetch the records anyway it + # is better to check <tt>collection.length.zero?</tt>. # # class Person < ActiveRecord::Base # has_many :pets diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb index 72b035a023..99e77e007a 100644 --- a/activerecord/lib/active_record/relation/calculations.rb +++ b/activerecord/lib/active_record/relation/calculations.rb @@ -111,8 +111,8 @@ module ActiveRecord 0 end - # 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. + # Use <tt>pluck</tt> 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) # @@ -121,7 +121,7 @@ module ActiveRecord # 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 + # the plucked column names, if they can be deduced. Plucking an SQL fragment # returns String values by default. # # Examples: |