<p>I'm looking for Ruby's Active record for PHP. Something that is so simple that I just define my fields, extend the base ORM class, and I get ACID operations for free. I should get default getters and setters without writing any code, but overriding a default getter or setter is as easy as declaring get$fieldName or set$fieldName functions with the behavior I want.  Symphony makes you create about 5 files per object, and all defined objects always load as far as I can tell. What is a better alternative? Why is it better? Can you put simple examples in your answers please?</p>

<p>Doctrine is another ORM I've looked at besides symphony . There also you need to create yaml files that describe your data structures. The database already defines this stuff. What will just read my table defs without having to generate and store config files everywhere?</p>

Zend_Db_Table
and
Zend_Db_Table_Row
are fairly good at what you're describing.  You don't need any configuration file, most metadata is "discovered" from the database itself.
Technically these classes don't implement the ActiveRecord pattern.  Instead, they implement the
Table Data Gateway
and
Row Data Gateway
patterns.  Together, these offer similar value as ActiveRecord, and in some ways are more flexible than ActiveRecord.
But as with any ORM, there are inevitably some SQL queries and operations that you can't do through the OO interface.  No ORM can serve as one-stop shopping.
Footnote:  I worked on the Zend Framework project for a little over a year, especially on the Zend_Db component.  But I don't work for them anymore.