How to use expression with '<' and '>' in CakePHP Model - cakephp

Question

How to generate this statement correctly from CakePHP?
DELETE FROM table as Table WHERE Table.expire < NOW();
I have tried this but this is not working:
$this->deleteAll(array(
'Table.expire <' => $this->getDataSource()->expression('NOW()')
));
//It complains:
SQLSTATE[42S22]: Column not found: 1054 Unknown column 'Table.expire <' in 'where clause'
SQL Query:
SELECT `Table`.`id` FROM `database`.`table` AS `Table` WHERE `Table.expire <` = NOW()
The only way to make it working now is by making the whole condition as a string:
$this->deleteAll('Table.expire < NOW()');
:: OR ::
$this->deleteAll(array('Table.expire < NOW()'));

Answer 1

I've tested your situation, because I was a bit surprised that CakePHP didn't properly 'quote'
Table.expire <
to
`Table`.`expire` <
(which it normally does).
This may be related to the fact that $this->getDataSource()->expression('NOW()') Returns a stdObject with 'NOW()' as a 'value' property. Maybe this is a 'special' case in the logic of CakePHP, I'm not really sure.
Array-notation assumes 'literal' values, not 'expressions'
Anyway, in general, the 'array notation' will regard the value passed a 'literal' value, not an expression, and therefore quote it as such, e.g.
'conditions' => array('Table.expire <' => 'some value')
'conditions' => array('Table.expire < ?' => 'another value')
'conditions' => array('Table.expire <' => 'NOW()')
Will all be regarded 'literal' values, resulting in these SQL conditions;
WHERE `Table`.`expire` < 'some value'
WHERE `Table`.`expire` < 'another value'
WHERE `Table`.`expire` < 'NOW()'
The values are thus regarded a string and 'NOW()' will not be seen as 'the current date/time' by the database.
Options
This will leave you with some options;
Specify the condition as a String, not a key/value array
You already provided this option in your question:
'conditions' => array('Table.expire < NOW()')
This solution should be safe in your situation (no user input is included in the statement), however, if user input will be included in such statement, it should be properly sanitized. Also, NOW() may not be valid cross-database (ANSI SQL uses CURRENT_TIMESTAMP for the current date/time)
Specify the current date/time as a ISO-date, not as an 'expression'
This is the alproach I normally use;
If you prefer the array-notation, you may consider to provide a 'literal' date for the condition, preferably as an ISO-date, which is handled properly by most databases;
'conditions' => array('Table.expire <' => date('Y-m-d H:i:s'))
// or
'conditions' => array('Table.expire < ?' => date('Y-m-d H:i:s'))
note I've created all my examples to be used as the 'conditions' key for a find(), however, the same will apply for a deleteAll()
Hope this helps!

Answer 2

Try this
$this->delete("all", array('conditions'=>array(
'Table.expire < ' => $this->getDataSource()->expression('NOW()')))
);