Difference between #9 and #8 of How to automate timestamps in ActiveRecord models

There are dozens ofmany ways to automate the setting of
timestamps in yii ActiveRecord models. Two ways you can do this
areof them are:

1. Via rules()
2. Via beforeSave()

To start off we need to create a database table.

    [sql]
    CREATE TABLE IF NOT EXISTS `Nodes` (
      `id` bigint(20) NOT NULL auto_increment,
      `title` varchar(255) NOT NULL,
      `created` datetime NOT NULL,
      `modified` datetime NOT NULL,
      PRIMARY KEY  (`id`)
    ) ENGINE=MyISAM  DEFAULT CHARSET=latin1 AUTO_INCREMENT=3
;);

Following this we'll generateAfter we have the table
we need to create a model with the Yii shell tool:and CRUD
for it by using Gii.

    model Node Nodes

To createCheck the crud functionality we
needguide on [How to type this:

    crud Nodegenerate model and CRUD with
Gii](http://www.yiiframework.com/doc/guide/1.1/en/quickstart.first-app#implementing-crud-operations
"How to generate model and CRUD with Gii").

The first way you can do it is via your model's rules.  Here is an example.

    [php]
	/**
	 * @return array validation rules for model attributes.
	 */
	public function rules()
	{
		return array(
			array('title','length','max'=>255),
			array('title, created, modified', 'required'),
            array('modified','default',
                  'value'=>new CDbExpression('NOW()'),
                  'setOnEmpty'=>false,'on'=>'update'),
            array('created,modified','default',
                  'value'=>new CDbExpression('NOW()'),
                  'setOnEmpty'=>false,'on'=>'insert')
		);
	}

You see the two rules at the end, one changes the modified field when the
record's being updated, and the other changes both fields when the record's
being created. You'll also see the "new CDbExpression('NOW()')"
statement. This passes "NOW()" to the MySQL server and it will not be
escaped. MySQL will interpret it as a statement and not as a string. This means
that the field types could have been any other date/time type (timestamp, etc.)
and it would still work.

Another solution is to use beforeSave() as follows:

	[php]
	public function beforeSave() {
		if ($this->isNewRecord)
			$this->created = new CDbExpression('NOW()');
		
		$this->modified		else
			$this->modified = new CDbExpression('NOW()');
			
		return parent::beforeSave();
	}

Note that in the above code, when creating a new record only the 'created' field
will be assigned/updated, while the 'modified' record will be assigned/updated
only when updating an existing record.

If you want to assign/update the 'modified' field even when creating a new
record... use this code:

	[php]
	public function beforeSave() {
		if ($this->isNewRecord)
			$this->created = new CDbExpression('NOW()');

		$this->modified = new CDbExpression('NOW()');
		
		return parent::beforeSave();
	}


These are simple and elegant solutions to this issue.