module ActiveRecord
# = Active Record Persistence
module Persistence
# Returns true if this object hasn't been saved yet -- that is, a record
# for the object doesn't exist in the data store 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.
# This is especially useful for boolean flags on existing records. Also note that
#
# * validation is skipped
# * No callbacks are invoked
# * updated_at/updated_on column is updated if that column is available
# * does not work on associations
# * does not work on attr_accessor attributes. The attribute that is being updated must be column name.
#
def update_attribute(name, value)
raise ActiveRecordError, "#{name.to_s} is marked as readonly" if self.class.readonly_attributes.include? name.to_s
changes = record_update_timestamps || {}
if name
name = name.to_s
send("#{name}=", value)
changes[name] = read_attribute(name)
end
@changed_attributes.except!(*changes.keys)
primary_key = self.class.primary_key
self.class.update_all(changes, { primary_key => self[primary_key] }) == 1
end
# Updates the attributes of the model from the passed-in hash and saves the
# record, all wrapped in a transaction. If the object is invalid, the saving
# will fail and false will be returned.
def update_attributes(attributes)
# The following transaction covers any possible database side-effects of the
# attributes assignment. For example, setting the IDs of a child collection.
with_transaction_returning_status do
self.attributes = attributes
save
end
end
# Updates its receiver just like +update_attributes+ but calls <tt>save!</tt> instead
# of +save+, so an exception is raised if the record is invalid.
def update_attributes!(attributes)
# The following transaction covers any possible database side-effects of the
# attributes assignment. For example, setting the IDs of a child collection.
with_transaction_returning_status do
self.attributes = attributes
save!
end
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.unscoped { 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
