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I am developing my own class model for my database and I would like to know what you guys think of it.

For each table in my database I have 2 classes. The first one, is a fetching class (I don't know how to call it..), this class has some static methods interacting with the database (fetchAll, fetchById etc..). The second class is the model itself, it contains all methods for a row of the table (insert, update, delete, validate or any other processing on the row).

Each of the fetching class returns the model object, if it's a fetchAll, for example, the method will return an array of model, and if its a fetchById the method will return only 1 object, since id is unique.

Example of how I would use it :

$users = Users_Map::fetchAll();

foreach($users as $user)
{
    echo $user->username.'<br/>';
}

$user = new User_Model();
$user->username = 'example';
$user->insert();

$user = User_Map::fetchById(1);
$user->username = 'example2';
$user->update();

If you have any suggestion other than _Map, I'm open. I'd like to know if this “pattern” is good and what do you think of it, how can I improve it, am I wrong? Should I use only 1 class, having static and non-static method all in the _Model?

Thank you very much for your help/suggestions!

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2 Answers 2

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Sounds reasonable from what you've described, though the true test will come when you start seriously extending it.

I usually build a core of three classes:

  1. a database handler
  2. a generic object handler
  3. a generic collection handler

Each table gets one derived from the object class to represent one row in the table, and a class derived from the collection which represents some or all of the table and will return individual objects as requested. There is also a static "registration" function for seting up all the necessary information (table name, valid fields, etc) once for each class.

Sometimes, a collection class is also an object for another table. The generic objects and the registration mechanism I wrote ages ago seamlessly handles this.

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4 Comments

How do you iterate through the collection class? I thought using arrays was the way to go, since it is light and it does not need any method to go back and froward through the collection
I've made it a generator. Iteration is done with while( $item = & $collection->next() ) { ... }. This completely frees the loop from dealing with the whole collection. In addition, the collection is coded to only retrieve each object as it's required. These two characteristics help prevent the common (memory) problem in PHP of moving around large arrays of data. I've never seen performance problems using this technique; instead I've seen big memory usage benefits.
Hi staticsan, do you have a sample code tutorial of this? sounds like your idea could help me in many ways
I don't have a tutorial, but I can point you at the same places I started with. Look at the classic loop to fetch a MySQL dataset: the core statement is while( $data = mysql_fetch_row($resultset) ) { ... }. If this function call is in an object method, you can put the resultset variable into an instance variable. Now your object can be a generator. Simply have the DB handler create a new such object for the return of each query. (I learnt about generators learning to program Icon.) Then this encapsulation approach can be extended to a collection object.
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That's the model I use in many of my applications, though for simplicity I combined the fetch-style methods into the same class as the insert()-type methods. This is particularly easy to do in PHP 5.3 with late-binding static members, so you your superclass-defined fetchById map can access the subclass-defined table_name variable (for example).

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2 Comments

Yeah, I am also considering of putting it all in one class... statics and non-static.. instance = 1 row.. static methods = fetching
@valli-R Just be careful you don't mixup the concept of IS-A and HAS-A. I've seen object models derive from a database handler, which not only doesn't make sense (because a database row HAS-A a handler, but you can't say it IS-A handler), it makes the heirarchy brittle which impedes maintenence.

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