OO Question

[NeoGeo]

I have a problem that would be perfectly solved with multiple constructors, but since those aren't allowed in PHP, I'd like to see how some of you are solving this problem:

Say I have a database full of customer records and in my PHP code I create a class called Customer as a data container. The problem is that there are two ways I want to construct the object:

1.) I want to create a Customer object with data from an existing record in the database.

2.) I want to create a Customer object AND insert a new record into the database.

For #1 I would create a constructor that would only take a database ID, query the db and populate the object's properties:

$customer = new Customer($id);

For #2 I would create a constructor that would take all the values so that it can use those to insert a new record in the DB and populate the object's properties.

$customer = new Customer($first_name, $last_name);

The only thing I can think of is to create a function that inserts the record, then run mysql_insert_id() to get ID of last inserted record, and use that ID to construct the class:

<?php

  insertCustomerRecord($first_name, $last_name);

  $id = mysql_insert_id();

  $customer = new Customer($id);

?>

But that just seems sloppy to me. Anyone have any better solutions to this problem?

[NogDog]

If using PHP5, I might use an abstract class:

abstract class Customer
{
   abstract public function __construct();

   // other methods common to all Customer type classes...
}

class ExistingCustomer extends Customer
{
   public function __construct($id)
   {
      // get data from DB based on $id
   }
}

class NewCustomer extends Customer
{
   public function __construct($firstname, $lastname)
   {
      // create new customer record in DB
   }
}

[Weedpacket]

Or you might use one constructor that does both, and decides which based on the number and types of its arguments; if there is only one numeric argument, then it's taken to be the ID of an existing record - otherwise, the arguments are the fields for the new record.

[greenie2600]

I agree with Weedpacket. I generally do something like this:

class Customer {

private $_db;
private $_id;

public function __construct( $db, $id = null ) {
    $this->_db = $db;
    $this->_id = $id;
    if ( !is_null( $id ) ) {
        $this->_loadFromDB();
    }
}

private function _loadFromDB() {
    // ... code to query DB and set properties...
}

}