eliminate alias_method_chain from ActiveRecord

1 files changed, 230 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/persistence.rb b/activerecord/lib/active_record/persistence.rb
new file mode 100644
index 0000000000..10788630a5
--- /dev/null
+++ b/activerecord/lib/active_record/persistence.rb
@@ -0,0 +1,230 @@
+module ActiveRecord
+  module Persistence
+    # Returns true if this object hasn't been saved yet -- that is, a record for the object doesn't exist yet; otherwise, returns false.
+    def new_record?
+      @new_record
+    end
+
+    # Returns true if this object has been destroyed, otherwise returns false.
+    def destroyed?
+      @destroyed
+    end
+
+    # Returns if the record is persisted, i.e. it's not a new record and it was not destroyed.
+    def persisted?
+      !(new_record? || destroyed?)
+    end
+
+    # :call-seq:
+    #   save(options)
+    #
+    # Saves the model.
+    #
+    # If the model is new a record gets created in the database, otherwise
+    # the existing record gets updated.
+    #
+    # By default, save always run validations. If any of them fail the action
+    # is cancelled and +save+ returns +false+. However, if you supply
+    # :validate => false, validations are bypassed altogether. See
+    # ActiveRecord::Validations for more information.
+    #
+    # There's a series of callbacks associated with +save+. If any of the
+    # <tt>before_*</tt> callbacks return +false+ the action is cancelled and
+    # +save+ returns +false+. See ActiveRecord::Callbacks for further
+    # details.
+    def save(*)
+      create_or_update
+    end
+
+    # Saves the model.
+    #
+    # If the model is new a record gets created in the database, otherwise
+    # the existing record gets updated.
+    #
+    # With <tt>save!</tt> validations always run. If any of them fail
+    # ActiveRecord::RecordInvalid gets raised. See ActiveRecord::Validations
+    # for more information.
+    #
+    # There's a series of callbacks associated with <tt>save!</tt>. If any of
+    # the <tt>before_*</tt> callbacks return +false+ the action is cancelled
+    # and <tt>save!</tt> raises ActiveRecord::RecordNotSaved. See
+    # ActiveRecord::Callbacks for further details.
+    def save!(*)
+      create_or_update || raise(RecordNotSaved)
+    end
+
+    # Deletes the record in the database and freezes this instance to
+    # reflect that no changes should be made (since they can't be
+    # persisted). Returns the frozen instance.
+    #
+    # The row is simply removed with a SQL +DELETE+ statement on the
+    # record's primary key, and no callbacks are executed.
+    #
+    # To enforce the object's +before_destroy+ and +after_destroy+
+    # callbacks, Observer methods, or any <tt>:dependent</tt> association
+    # options, use <tt>#destroy</tt>.
+    def delete
+      self.class.delete(id) if persisted?
+      @destroyed = true
+      freeze
+    end
+
+    # Deletes the record in the database and freezes this instance to reflect that no changes should
+    # be made (since they can't be persisted).
+    def destroy
+      if persisted?
+        self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).delete_all
+      end
+
+      @destroyed = true
+      freeze
+    end
+
+    # Returns an instance of the specified +klass+ with the attributes of the current record. This is mostly useful in relation to
+    # single-table inheritance structures where you want a subclass to appear as the superclass. This can be used along with record
+    # identification in Action Pack to allow, say, <tt>Client < Company</tt> to do something like render <tt>:partial => @client.becomes(Company)</tt>
+    # to render that instance using the companies/company partial instead of clients/client.
+    #
+    # Note: The new instance will share a link to the same attributes as the original class. So any change to the attributes in either
+    # instance will affect the other.
+    def becomes(klass)
+      became = klass.new
+      became.instance_variable_set("@attributes", @attributes)
+      became.instance_variable_set("@attributes_cache", @attributes_cache)
+      became.instance_variable_set("@new_record", new_record?)
+      became.instance_variable_set("@destroyed", destroyed?)
+      became
+    end
+
+    # Updates a single attribute and saves the record without going through the normal validation procedure.
+    # This is especially useful for boolean flags on existing records. The regular +update_attribute+ method
+    # in Base is replaced with this when the validations module is mixed in, which it is by default.
+    def update_attribute(name, value)
+      send("#{name}=", value)
+      save(:validate => false)
+    end
+
+    # Updates all the attributes from the passed-in Hash and saves the record. If the object is invalid, the saving will
+    # fail and false will be returned.
+    def update_attributes(attributes)
+      self.attributes = attributes
+      save
+    end
+
+    # Updates an object just like Base.update_attributes but calls save! instead of save so an exception is raised if the record is invalid.
+    def update_attributes!(attributes)
+      self.attributes = attributes
+      save!
+    end
+
+    # Initializes +attribute+ to zero if +nil+ and adds the value passed as +by+ (default is 1).
+    # The increment is performed directly on the underlying attribute, no setter is invoked.
+    # Only makes sense for number-based attributes. Returns +self+.
+    def increment(attribute, by = 1)
+      self[attribute] ||= 0
+      self[attribute] += by
+      self
+    end
+
+    # Wrapper around +increment+ that saves the record. This method differs from
+    # its non-bang version in that it passes through the attribute setter.
+    # Saving is not subjected to validation checks. Returns +true+ if the
+    # record could be saved.
+    def increment!(attribute, by = 1)
+      increment(attribute, by).update_attribute(attribute, self[attribute])
+    end
+
+    # Initializes +attribute+ to zero if +nil+ and subtracts the value passed as +by+ (default is 1).
+    # The decrement is performed directly on the underlying attribute, no setter is invoked.
+    # Only makes sense for number-based attributes. Returns +self+.
+    def decrement(attribute, by = 1)
+      self[attribute] ||= 0
+      self[attribute] -= by
+      self
+    end
+
+    # Wrapper around +decrement+ that saves the record. This method differs from
+    # its non-bang version in that it passes through the attribute setter.
+    # Saving is not subjected to validation checks. Returns +true+ if the
+    # record could be saved.
+    def decrement!(attribute, by = 1)
+      decrement(attribute, by).update_attribute(attribute, self[attribute])
+    end
+
+    # Assigns to +attribute+ the boolean opposite of <tt>attribute?</tt>. So
+    # if the predicate returns +true+ the attribute will become +false+. This
+    # method toggles directly the underlying value without calling any setter.
+    # Returns +self+.
+    def toggle(attribute)
+      self[attribute] = !send("#{attribute}?")
+      self
+    end
+
+    # Wrapper around +toggle+ that saves the record. This method differs from
+    # its non-bang version in that it passes through the attribute setter.
+    # Saving is not subjected to validation checks. Returns +true+ if the
+    # record could be saved.
+    def toggle!(attribute)
+      toggle(attribute).update_attribute(attribute, self[attribute])
+    end
+
+    # Reloads the attributes of this object from the database.
+    # The optional options argument is passed to find when reloading so you
+    # may do e.g. record.reload(:lock => true) to reload the same record with
+    # an exclusive row lock.
+    def reload(options = nil)
+      clear_aggregation_cache
+      clear_association_cache
+      @attributes.update(self.class.send(:with_exclusive_scope) { self.class.find(self.id, options) }.instance_variable_get('@attributes'))
+      @attributes_cache = {}
+      self
+    end
+
+  private
+    def create_or_update
+      raise ReadOnlyRecord if readonly?
+      result = new_record? ? create : update
+      result != false
+    end
+
+    # Updates the associated record with values matching those of the instance attributes.
+    # Returns the number of affected rows.
+    def update(attribute_names = @attributes.keys)
+      attributes_with_values = arel_attributes_values(false, false, attribute_names)
+      return 0 if attributes_with_values.empty?
+      self.class.unscoped.where(self.class.arel_table[self.class.primary_key].eq(id)).arel.update(attributes_with_values)
+    end
+
+    # Creates a record with values matching those of the instance attributes
+    # and returns its id.
+    def create
+      if self.id.nil? && connection.prefetch_primary_key?(self.class.table_name)
+        self.id = connection.next_sequence_value(self.class.sequence_name)
+      end
+
+      attributes_values = arel_attributes_values
+
+      new_id = if attributes_values.empty?
+        self.class.unscoped.insert connection.empty_insert_statement_value
+      else
+        self.class.unscoped.insert attributes_values
+      end
+
+      self.id ||= new_id
+
+      @new_record = false
+      id
+    end
+
+    # Initializes the attributes array with keys matching the columns from the linked table and
+    # the values matching the corresponding default value of that column, so
+    # that a new instance, or one populated from a passed-in Hash, still has all the attributes
+    # that instances loaded from the database would.
+    def attributes_from_column_definition
+      self.class.columns.inject({}) do |attributes, column|
+        attributes[column.name] = column.default unless column.name == self.class.primary_key
+        attributes
+      end
+    end
+  end
+end
\ No newline at end of file