associative array vs object

[I like pie]

I'm pretty new to OOP, and I've got a handle on the concept... but I'm still having trouble with actually using objects. I'm unsure if that's actually what I want in my current situation.

I'm re-writing an old game I made a few years back, and before what I would do to display a player's data on his "hq" page would be to query his id in the players table, and assign all that data to a $players[] array.

Now, I'm thinking it may be better to create a player object. But I'm not quite sure how to go about putting the info from a player's row in the db into the player object.

So far, this is what I have:

 class player {
    var $username;
    var $last_login;

    function player($playerName, $playerLastLogin) {
      $this->username = $playerName;
      $this->last_login = $playerLastLogin;
    }

So... when i instantiate a player, I need to pass it those 2 values, but it seems really strange to pull those values from the db into a variable just to pass them along to an object variable...

Is this making any sense? I don't quite know how to gracefully populate a player object with data from the players table in the db. I know just using an array like before would work for now, but I'm sure a player object is the better way to go.

[Arenlor]

I like arrays, I think they are better than objects. I started my programming career in C, then C++, then Java, now PHP, I love just using $arr = mysql_fetch_array($val); it's so useful. And way easier.

[I like pie]

Yeah, that's what appealing to me right now. It seems so clean to just create an array to represent a row, which in turn represents a player's basic information.

But at the same time I really like the idea of having objects that not only represent something, but can also carry out tasks.

Although, I suppose I could easily enough write functions that take an array as a parameter.

Decisions... =/

[Hades]

You can write a small script to automatically create objects from the results of a database query.

I have a database wrapper which I wrote for PHP and works like a recordset. Besides, I create classes to represent entities.

My class looks like this:

PHP Code:


class Player{

  function get($filters){
     $sql = "SELECT... from player ";
     if ($filters) $sql .= "WHERE " . $filters;
     $rData = SQL::query($sql);
     return($rData);
  }

} 


Then my frontend code looks like this:

PHP Code:


$rData = Player::get("name LIKE 'Cris%'");

for($i=0;$i<$rData->quantity();$i++){
   echo( $rData->field("name",$i) . "<br/>" );
} 


I used 3 classes there:
Class Player, which represents the player entity.
Class SQL, that acts like a database wrapper.
Class Data, that works like a recordset to manage the data.

I can post the code of these classes if you want. Let me know!

[I like pie]

It would be helpful if you could. =) I've got the idea of what you're saying, but I wouldn't know how to start implementing it.

[Hades]

OK, here we go...

First, you have three files, one that acts like a database connector, another that acts as a dataaccess wrapper and the last one will work as a recordset.

Database.php

PHP Code:


class Database{
        function connect( $hostname, $user, $password, $db )
        {
            static $connected;
            
            if ($connected) return;
            
            $connId = @mysql_connect($hostname, $user, $password) or die('Cannot connect to database server');
            @mysql_select_db($db) or die('The database is currently down');
            $connected = true;
            return $connId;
        }
        function close(){
            mysql_close();
            return;
        }
} 


SQL.php

PHP Code:

class SQL {
    
    /**
     * @desc executes a single DDL query
     *
     * @param string $sql
     * @param integer $queryType
     * @param integer-pointer $id
     * @param string-pointer $error
     * @return $result
     */
    function execute($sql, $queryType, &$id,&$error,$log=true)
    {
        Database::connect("host","username", "password", "database");
                
        $sqlTransact = $sql;
        $result = mysql_query($sql);
        if($queryType=="DBINSERT") 
        {
            $id = @mysql_insert_id();
        }
        
        if (mysql_errno()){
            $error = mysql_error()."\nQuery: " . $sql;
        }
        
        Database::close();
        return $result;
    }
    
    
    /**
     * @desc executes a single DML query
     *
     * @param string $sql
     * @return Data $rs
     */
    function query($sql)
    {
        Database::connect($_SESSION['sess_conf']['db_hostname'],$_SESSION['sess_conf']['db_username'], $_SESSION['sess_conf']['db_password'], $_SESSION['sess_conf']['db_database']);
        $rs =  mysql_query($sql) or die(mysql_error() . "<br><b>QUERY</b>:<br>" . nl2br($sql));
        if(mysql_num_rows($rs) >0)
        {
            for($i=0; $i< mysql_num_fields($rs); $i++)
                $fields[mysql_field_name($rs, $i)] = $i;

            while ($row = mysql_fetch_row($rs))
                $vec[] = $row;

            mysql_free_result($rs);
            Database::close();
            return new Data($fields, $vec);
        }
        Database::close();
        return new Data();
    }
    
} 


Data.php

PHP Code:

class Data {
    
    var $_fields = "";
    var $_data  = "";
    
    function Data($_fields=Array(), $_data=Array())
    {
        $this->_fields = $_fields;
        $this->_data = &$_data;
    }
    
    /**
     * count the result
     *
     * @return int
     */
    function quantity() {
        return count($this->_data);
    }
    
    /**
     * count columns
     *
     * @return int
     */
    function quantityFields() {
        return count($this->_fields);
    }
    
    /**
     * get the Field
     * 
     * @param String $field
     * @param int $row
     * 
     * @return mixed
     */    
    function field($field, $row)
    {
        $value = $this->_data[$row][$this->_fields[$field]];
        return $value;
    }
    
    /**
     * get the colum name
     * 
     * @param String $fieldCol
     * 
     * @return String
     */
    function fieldNameByPosition($fieldCol)
    {
        $aFields = array_keys($this->_fields);
        return $aFields[$fieldCol];
    }
    
    /**
     * get the field position by name
     *
     * @param String $name
     * @return int
     */
    function getFieldPositionByName($name)    {
        
        if (!array_key_exists($name, $this->_fields)) {
            return false;
        }
        
        return $this->_fields[$name];
    }
    
    /**
     * get the Field
     * 
     * @param int $field
     * @param int $row
     * 
     * @return mixed
     */
    function fieldByPosition($field, $row)
    {
        $value = $this->_data[$row][$field];
        return $value;
    }
    
    /**
     * make an array.
     *
     * @return Array
     */
    function &getArray(){
        $aResponse = array();
        $keys = array_keys($this->_fields);
        
        for($i=0;$i<count($this->_data);$i++){
            $aResponse[$i] = array();
            foreach($keys as $k){
                $aResponse[$i][$k] = $this->_data[$i][$this->_fields[$k]];
            }
        }
        return ($aResponse);
    }
    
    
    function getColsNames()    {
        
        return array_keys($this->_fields);
    }
    
    
} 


Then, you will have a class for each entity in your system, if you need a Player entity, my class looks like the one as follows:

Player.php

PHP Code:

/**
 *    Class Player
 *    Class for player management
 *    
 *    Related Table: player
 *    Alias: pl
 *    ID: idPlayer
 *    Label: name
 *    Relative Path:  
 *    
 *    Author: Chris @ Liberty Web Systems
 *    Date: Wed Jan 31 22:38:39 ART 2007
**/
class Player {
    
    /**
     * Returns a filtered list from player (pl)...
     *
     * @param integer $id
     * @param string $filters
     * @param string $order
     * @param string $limit
     * @return Data
     */
    function get($id="",$filters="",$order="",$limit=""){
        global $_SYS;
        $sql = "
        SELECT 
            pl.idPlayer,
            pl.* 
        FROM player pl
        WHERE 1
        ";
        if ($id) $sql .= " AND pl.idPlayer = '".$id."'";
        if ($filters) $sql .= "AND " . $filters;
        if ($order) $sql .= " ORDER BY " . $order;
        if ($limit) $sql .= " LIMIT $limit";
        
        $rData = SQL::query($sql);
        return ($rData);
    }
    
    /**
     * Returns the count of registries from a filtered list
     *
     * @param integer $id
     * @param string $filters
     * @return integer
     */
    function countRegistries($id="",$filters=""){
        global $_SYS;
        $sql = " SELECT COUNT(pl.idPlayer) as cnt FROM player pl WHERE 1 ";
        if ($id) $sql .= " AND idPlayer = '".$id."' ";
        if ($filters) $sql .= " AND " . $filters;
        
        $rData = SQL::query($sql);
        return ($rData->field("cnt",0));
    }
    
    
    /**
     * Inserts a new registry into player
     *
     * @param array $aData
     * @return integer
     */
    function insert($aData){
        
        
        $sql = "
        INSERT INTO player
        (
            name,
            dateAdded,
            team,
            points
        )
        VALUES
        (
            '".$aData['name']."',
            '".$aData['dateAdded']."',
            '".$aData['team']."',
            '".$aData['points']."'
        )
        ";
        SQL::execute($sql,DBINSERT,$id,$error);
        return($id);
    }
    
    /**
     * Modifies a registry from player
     *
     * @param integer $id
     * @param array $aData
     * @return integer
     */
    function update($id,$aData){
        
        $sql = "
        UPDATE player SET
            
            name = '".$aData['name']."',
            dateAdded = '".$aData['dateAdded']."',
            team = '".$aData['team']."',
            points = '".$aData['points']."'
        WHERE idPlayer = '".$id."'";
        
        SQL::execute($sql,"DBUPDATE",$id,$error);
    
    }
    
    /**
     * Deletes a registry from player
     *
     * @param integer $id
     */
    function delete($id){
        global $_SYS;
        $sql = "DELETE FROM player WHERE idPlayer = $id";
        SQL::execute($sql,"DBDELETE",$id,$error);
    }
    
    
} 


After including these files one can start programming (okok that was a joke!)

Lets suppose that you need to display a list of players, you can do something like this:

PHP Code:

include("Database.php");
include("SQL.php");
include("Data.php");
include("Player.php");

//Dummy Data.
$idPlayer = 1;

//a simple, "select all" query.
$rDataAll = Player::get();

//select only one player.
$rDataOnlyOne = Player::get($idPlayer);

//select by filter
$rDataFiltered = Player::get(false," points > '100'");

/*FOR FURTHER INFORMATION ON HOW TO USE THE GET FUNCTION, READ ITS PROTOTYPE ON THE PLAYER CLASS*/ 


Now you have three recordsets, you can read them with this code

PHP Code:

for($i=0;$i<$rDataAll->quantity();$i++){
    echo("
    Name = ".$rDataAll->field("name",$i)." <br/>
    Added = ".$rDataAll->field("dateAdded",$i)." <br/>
    Team = ".$rDataAll->field("team",$i)." <br/>
    Points = ".$rDataAll->field("points",$i)." <br/>
    <hr/>
    ");
} 


To insert a registry into the player table, you can use this code:

PHP Code:

$aData = array(
 "name"=>"Jack",
 "dateAdded"=>"2007-01-01",
 "team"=>"blue",
 "points"=>1000
);

Player::insert($aData); 


You can do something similar in order to update and delete registries, take a look at the prototypes of the Player class (documentation is very useful )

This is how I work, however, any suggestion will be accepted. Post your questions if you need any kind of help, we are all here to learn!

[I like pie]

Well holy crap. That's quite... pretty

Thanks a ton, I'm gonna play around with all that to get a feel for how it all works. I'm pretty impressed, that's rather clean code you've got there