Place class level `update`, `destroy`, and `delete` in `Persistence::ClassMethods`

The docs are obviously for class level `update`, `destroy`, and
`delete`. It should be placed in `Persistence::ClassMethods` rather than
`Relation`. And also, these methods are not dependent on relation. So it
is not needed to delegate to `all` (plus, `klass.find` is faster than
`relation.find`).

1 files changed, 92 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
index fbbf9082cc..4a5ccdc597 100644
--- a/activerecord/lib/active_record/persistence.rb
+++ b/activerecord/lib/active_record/persistence.rb
@@ -71,6 +71,98 @@ module ActiveRecord
         klass.allocate.init_with("attributes" => attributes, "new_record" => false, &block)
       end
 
+      # Updates an object (or multiple objects) and saves it to the database, if validations pass.
+      # The resulting object is returned whether the object was saved successfully to the database or not.
+      #
+      # ==== Parameters
+      #
+      # * +id+ - This should be the id or an array of ids to be updated.
+      # * +attributes+ - This should be a hash of attributes or an array of hashes.
+      #
+      # ==== Examples
+      #
+      #   # Updates one record
+      #   Person.update(15, user_name: "Samuel", group: "expert")
+      #
+      #   # Updates multiple records
+      #   people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
+      #   Person.update(people.keys, people.values)
+      #
+      #   # Updates multiple records from the result of a relation
+      #   people = Person.where(group: "expert")
+      #   people.update(group: "masters")
+      #
+      # Note: Updating a large number of records will run an UPDATE
+      # query for each record, which may cause a performance issue.
+      # When running callbacks is not needed for each record update,
+      # it is preferred to use {update_all}[rdoc-ref:Relation#update_all]
+      # for updating all records in a single query.
+      def update(id = :all, attributes)
+        if id.is_a?(Array)
+          id.map.with_index { |one_id, idx| update(one_id, attributes[idx]) }
+        elsif id == :all
+          all.each { |record| record.update(attributes) }
+        else
+          if ActiveRecord::Base === id
+            raise ArgumentError,
+              "You are passing an instance of ActiveRecord::Base to `update`. " \
+              "Please pass the id of the object by calling `.id`."
+          end
+          object = find(id)
+          object.update(attributes)
+          object
+        end
+      end
+
+      # Destroy an object (or multiple objects) that has the given id. The object is instantiated first,
+      # therefore all callbacks and filters are fired off before the object is deleted. This method is
+      # less efficient than #delete but allows cleanup methods and other actions to be run.
+      #
+      # This essentially finds the object (or multiple objects) with the given id, creates a new object
+      # from the attributes, and then calls destroy on it.
+      #
+      # ==== Parameters
+      #
+      # * +id+ - Can be either an Integer or an Array of Integers.
+      #
+      # ==== Examples
+      #
+      #   # Destroy a single object
+      #   Todo.destroy(1)
+      #
+      #   # Destroy multiple objects
+      #   todos = [1,2,3]
+      #   Todo.destroy(todos)
+      def destroy(id)
+        if id.is_a?(Array)
+          id.map { |one_id| destroy(one_id) }
+        else
+          find(id).destroy
+        end
+      end
+
+      # Deletes the row with a primary key matching the +id+ argument, using a
+      # SQL +DELETE+ statement, and returns the number of rows deleted. Active
+      # Record objects are not instantiated, so the object's callbacks are not
+      # executed, including any <tt>:dependent</tt> association options.
+      #
+      # You can delete multiple rows at once by passing an Array of <tt>id</tt>s.
+      #
+      # Note: Although it is often much faster than the alternative, #destroy,
+      # skipping callbacks might bypass business logic in your application
+      # that ensures referential integrity or performs other essential jobs.
+      #
+      # ==== Examples
+      #
+      #   # Delete a single row
+      #   Todo.delete(1)
+      #
+      #   # Delete multiple rows
+      #   Todo.delete([2,3,4])
+      def delete(id_or_array)
+        where(primary_key => id_or_array).delete_all
+      end
+
       private
         # Called by +instantiate+ to decide which class to use for a new
         # record instance.