Re: DataObject & calculated fields

On Friday 23 January 2004 01:02 pm, Norbert Mocsnik wrote: > Hi again, > > Yesterday I was thinkin about DataObject and calculated fields.. > I know calcfields from Delphi and find them really useful. The main idea > is very simple: let the developer be able to create new fields in any > table, from code. The value of this field is calculated on-the-fly after > fetching a record. Imagine a simple scenario about user profiles: > users > ----- > userid > first_name > last_name > .. > > You can create a (virtual) field from code called full_name which > contains the concatenation of first and last name fields. I did the > following: > Sounds like a good place to use stored procedures. > 1. added a new function to the DataObject core: > function _calcFields() { > if (method_exists($this, 'calcFields')) { > $this->calcFields(); > } > } > > 2. at the end of fetch() (before "return true;") I call: > $this->_calcFields(); > so my function will be called every time after fetching a record. > * Note: I'm not sure about where to place this call. I'm not sure this > will be called after every fetch because there are fetches when the > fetch() function itself won't be called. It would be nice if someone > could help me to find the points to call it from. > I have something similar, DataObject_Filter[1]. It's got more features, as it allows you to have a function triggered after fetch, and before insert and update. Handlers are field-specific, and can be stacked. So, for example, I use it to strip backslashes off strings stored in the database. I have a function called _filterStripSlashes() which does this, and in my DataObject's constructor I call: $this->addFilter('fetch', 'stringField', array(get_class($this), '_filterStripSlashes')); And that registers the filter, and your field is automagically processed. I also use it for transparent encryption of passwords, like so: function _filterMD5Password(&$object, $field) { $object->$field = md5($object->$field); } and in the constructor: $this->addFilter('insert', 'password', array(get_class($this), '_filterMD5Password')); $this->addFilter('update', 'password', array(get_class($this), '_filterMD5Password')); So when you insert or update, you just set the plaintext password in the DataObject, and it's encrypted before it goes into the database. [1]: http://www.websprockets.com/~ieure/PEAR/