construct giving me problems

[9three]

Before adding my __construct my class was working fine, but I figured I would cut down some code by when I initiate the class, within the same parenthesis add the parameters as well.

 

index.php

  $connection = new mysql('localhost', 'root', '');
  $connection->select('cms');

 

Before I added my construct:

  $connection = new mysql();
  $connection->connect('localhost', 'root', '');
  $connection->select('cms');

 

Anyway, It's throwing me an exception:

 

Fatal error: Uncaught exception 'Exception' with message 'Unable to select database' in C:\Users\9three\Desktop\Server\htdocs\CMS\admin\includes\library\mysql.class.php:30 Stack trace: #0 C:\Users\9three\Desktop\Server\htdocs\CMS\admin\index.php(: mysql->select('cms') #1 {main} thrown in C:\Users\9three\Desktop\Server\htdocs\CMS\admin\includes\library\mysql.class.php on line 30

 

As well as a MySQL error:

 

Warning: mysql_select_db(): supplied argument is not a valid MySQL-Link resource in C:\Users\9three\Desktop\Server\htdocs\CMS\admin\includes\library\mysql.class.php on line 27

 

mysql.class.php

  public $host, $user, $password;
  public $link, $select, $query, $fetch;
  
  public function __construct($host, $user, $password)
  {
    $this->host = $host;
    $this->user = $user;
    $this->password = $password;
  }

  public function connect()
  {
    $this->link = mysql_connect($this->host, $this->user, $this->password);
    if (!$this->link)
    {
      Throw New Exception('Unable to connect');
    }
  }

  public function select($select)
  {
    $this->select = mysql_select_db($select, $this->link);
    if (!$this->select)
    {
      Throw New Exception('Unable to select database');
    }
  }

 

my method select was working fine before...

[corbin]

It needs to know if it's connected or not if you don't plan on telling it to connect.

 

 

Something like (psuedo code, in the select function):

 

if(not connected) {

    connect;

}

 

Or, you could just change the construct to:

 

 

public function __construct($host, $user, $password)

  {

    $this->host = $host;

    $this->user = $user;

    $this->password = $password;

    $this->connect();

    $this->select();

  }

 

 

Sometimes 'lazy' connections are done on purpose though.  That way, the over head is smaller of an unused DB class.

[DarkWater]

It's all well and good that you're passing things into the constructor, but you're not actually connecting.  Try changing __construct() to:

  public function __construct($host, $user, $password)
  {
    $this->host = $host;
    $this->user = $user;
    $this->password = $password;
    $this->connect();
  }

 

Also, I'd suggest making the variables private, not public.

[9three]

It needs to know if it's connected or not if you don't plan on telling it to connect.

 

 

Something like (psuedo code, in the select function):

 

if(not connected) {

    connect;

}

 

Or, you could just change the construct to:

 

 

public function __construct($host, $user, $password)

  {

    $this->host = $host;

    $this->user = $user;

    $this->password = $password;

    $this->connect();

    $this->select();

  }

 

 

Sometimes 'lazy' connections are done on purpose though.  That way, the over head is smaller of an unused DB class.

 

So are you saying that using $this->connect() in the constructor is the lazy way? Which way would be the not-lazy way?

[corbin]

Nooooo....

 

 

Lazily connection is a design term (sort of... more of a strategy or something).  The first time I saw it was in Zend_Db, but I bet it's been around a long time.

 

The concept of lazy connections basically is this:

 

-Tell the DB instance the data it knows to connect, but do not have it connect.

-When a query is run or something else requiring a database connection, then try to make the connection.

 

The reasoning behind it is that if the DB class is never used, the DB connection is never made, therefore [as much] time isn't wasted.

[DarkWater]

No, lazy connections are connections that are initialized on-demand.  Like, if you just instantiated a DB class, it wouldn't connect until you actually did your first operation, which could save some memory and resources.  Depends on what you're actually trying to do.

[9three]

Normally I only connect to a database when i HAVE to.

 

So basically what you are saying is that if I do something like

 

public function select($select)

{

  $this->connect();

  $this->query = mysql_select_db($select, $this->link);

}

 

It would actually be better?