Module: ActiveRecord::Persistence

Defined in:
lib/active_record/persistence.rb

Overview

Active Record Persistence

Instance Method Summary collapse

Instance Method Details

#becomes(klass) ⇒ Object

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, Client < Company to do something like render :partial => @client.becomes(Company) 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.



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# File 'lib/active_record/persistence.rb', line 111

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.type = klass.name unless self.class.descends_from_active_record?
  became
end

#decrement(attribute, by = 1) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 198

def decrement(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] -= by
  self
end

#decrement!(attribute, by = 1) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 208

def decrement!(attribute, by = 1)
  decrement(attribute, by).update_attribute(attribute, self[attribute])
end

#delete ⇒ Object

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 an 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 :dependent association options, use #destroy.



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# File 'lib/active_record/persistence.rb', line 70

def delete
  if persisted?
    self.class.delete(id)
    IdentityMap.remove(self) if IdentityMap.enabled?
  end
  @destroyed = true
  freeze
end

#destroy ⇒ Object

Deletes the record in the database and freezes this instance to reflect that no changes should be made (since they can’t be persisted).



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# File 'lib/active_record/persistence.rb', line 81

def destroy
  destroy_associations

  if persisted?
    IdentityMap.remove(self) if IdentityMap.enabled?
    pk         = self.class.primary_key
    column     = self.class.columns_hash[pk]
    substitute = connection.substitute_at(column, 0)

    relation = self.class.unscoped.where(
      self.class.arel_table[pk].eq(substitute))

    relation.bind_values = [[column, id]]
    relation.delete_all
  end

  @destroyed = true
  freeze
end

#destroyed? ⇒ Boolean

Returns true if this object has been destroyed, otherwise returns false.

Returns:

  • (Boolean) 


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# File 'lib/active_record/persistence.rb', line 11

def destroyed?
  @destroyed
end

#increment(attribute, by = 1) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 181

def increment(attribute, by = 1)
  self[attribute] ||= 0
  self[attribute] += by
  self
end

#increment!(attribute, by = 1) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 191

def increment!(attribute, by = 1)
  increment(attribute, by).update_attribute(attribute, self[attribute])
end

#new_record? ⇒ Boolean

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.

Returns:

  • (Boolean) 


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# File 'lib/active_record/persistence.rb', line 6

def new_record?
  @new_record
end

#persisted? ⇒ Boolean

Returns if the record is persisted, i.e. it’s not a new record and it was not destroyed.

Returns:

  • (Boolean) 


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# File 'lib/active_record/persistence.rb', line 17

def persisted?
  !(new_record? || destroyed?)
end

#reload(options = nil) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 233

def reload(options = nil)
  clear_aggregation_cache
  clear_association_cache

  IdentityMap.without do
    fresh_object = self.class.unscoped { self.class.find(self.id, options) }
    @attributes.update(fresh_object.instance_variable_get('@attributes'))
  end

  @attributes_cache = {}
  self
end

#save ⇒ Object

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 before_* callbacks return false the action is cancelled and save returns false. See ActiveRecord::Callbacks for further details.



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# File 'lib/active_record/persistence.rb', line 35

def save(*)
  begin
    create_or_update
  rescue ActiveRecord::RecordInvalid
    false
  end
end

#save! ⇒ Object

Saves the model.

If the model is new a record gets created in the database, otherwise the existing record gets updated.

With save! 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 save!. If any of the before_* callbacks return false the action is cancelled and save! raises ActiveRecord::RecordNotSaved. See ActiveRecord::Callbacks for further details.



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# File 'lib/active_record/persistence.rb', line 56

def save!(*)
  create_or_update || raise(RecordNotSaved)
end

#toggle(attribute) ⇒ Object

Assigns to attribute the boolean opposite of attribute?. So if the predicate returns true the attribute will become false. This method toggles directly the underlying value without calling any setter. Returns self.



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# File 'lib/active_record/persistence.rb', line 216

def toggle(attribute)
  self[attribute] = !send("#{attribute}?")
  self
end

#toggle!(attribute) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 225

def toggle!(attribute)
  toggle(attribute).update_attribute(attribute, self[attribute])
end

#touch(name = nil) ⇒ Object

Saves the record with the updated_at/on attributes set to the current time. Please note that no validation is performed and no callbacks are executed. If an attribute name is passed, that attribute is updated along with updated_at/on attributes.

product.touch               # updates updated_at/on
product.touch(:designed_at) # updates the designed_at attribute and updated_at/on

If used along with belongs_to then touch will invoke touch method on associated object.

class Brake < ActiveRecord::Base
  belongs_to :car, :touch => true
end

class Car < ActiveRecord::Base
  belongs_to :corporation, :touch => true
end

# triggers @brake.car.touch and @brake.car.corporation.touch
@brake.touch



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# File 'lib/active_record/persistence.rb', line 266

def touch(name = nil)
  attributes = timestamp_attributes_for_update_in_model
  attributes << name if name

  unless attributes.empty?
    current_time = current_time_from_proper_timezone
    changes = {}

    attributes.each do |column|
      changes[column.to_s] = write_attribute(column.to_s, current_time)
    end

    changes[self.class.locking_column] = increment_lock if locking_enabled?

    @changed_attributes.except!(*changes.keys)
    primary_key = self.class.primary_key
    self.class.unscoped.update_all(changes, { primary_key => self[primary_key] }) == 1
  end
end

#update_attribute(name, value) ⇒ Object

Updates a single attribute and saves the record. This is especially useful for boolean flags on existing records. Also note that

  • Validation is skipped.

  • Callbacks are invoked.

  • updated_at/updated_on column is updated if that column is available.

  • Updates all the attributes that are dirty in this object.

Raises:



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# File 'lib/active_record/persistence.rb', line 129

def update_attribute(name, value)
  name = name.to_s
  raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
  send("#{name}=", value)
  save(:validate => false)
end

#update_attributes(attributes, options = {}) ⇒ Object

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.

When updating model attributes, mass-assignment security protection is respected. If no :as option is supplied then the :default role will be used. If you want to bypass the protection given by attr_protected and attr_accessible then you can do so using the :without_protection option.



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# File 'lib/active_record/persistence.rb', line 158

def update_attributes(attributes, options = {})
  # 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.assign_attributes(attributes, options)
    save
  end
end

#update_attributes!(attributes, options = {}) ⇒ Object

Updates its receiver just like update_attributes but calls save! instead of save, so an exception is raised if the record is invalid.



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# File 'lib/active_record/persistence.rb', line 169

def update_attributes!(attributes, options = {})
  # 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.assign_attributes(attributes, options)
    save!
  end
end

#update_column(name, value) ⇒ Object

Updates a single attribute of an object, without calling save.

  • Validation is skipped.

  • Callbacks are skipped.

  • updated_at/updated_on column is not updated if that column is available.

Raises:



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# File 'lib/active_record/persistence.rb', line 142

def update_column(name, value)
  name = name.to_s
  raise ActiveRecordError, "#{name} is marked as readonly" if self.class.readonly_attributes.include?(name)
  raise ActiveRecordError, "can not update on a new record object" unless persisted?
  raw_write_attribute(name, value)
  self.class.update_all({ name => value }, self.class.primary_key => id) == 1
end