Class

[ab4net]

HI all ..
how are you amazing people ...
hmmm, i wanted to ask if some one can help me in the classes thing, am a programmer, and developer, and i never use classes, and all my programs working fine, can any one teach me here in a few words, what t is better for, and if there is few links can lead me to A-Z knowledge and details "Tutorials" about the classes ...

thank you all in advance ..

Regards,

[bretticus]

Well, I assume you've been to the manual. Just in case, here's a link that has some examples, etc:

http://us3.php.net/language.oop

Also, here's a discussion thread on why to use classes and OOP:

http://www.phpbuilder.com/board/showthread.php?threadid=10295468&highlight=class

[ab4net]

Thank yo very much,
then i think i have to search for classes tutorials 😃

if you know some good classes tutorials, that'll be helpful ...

many thanks ...

[ab4net]

here is a good link, i have found, it is so useful, for classes beginers starts from zero :

http://www.php-editors.com/articles/simple_php_classes.php

regards,

[bretticus]

That is a very good beginner's tutorial. I'll be sure to pass it on to the next person who inquires.

One thing that it does leave out that is of worth, is the concept and use of a contructor. If you create a function within the class with the same name as the class, it's code will be executed when you call the class. This is useful to initialize variables, pass arguments to your class, etc. An example might be:

require("database.class.php");
$db = new DataBase("localhost", "mydb", "myuser", "mypasswd");

and within the class...

Class DataBase {
	var $link
	function DataBase($host, $database, $user, $passwd) {
		$this->link = mysql_connect($host, $user, $passwd);
		if (!$this->link) {
		   die('Could not connect: ' . mysql_error());
		}
		$db_selected = mysql_select_db($database, $this->link);
		if (!$db_selected) {
		   die ('Can\'t use $database : ' . mysql_error());
		}
	}
}

[ShawnK]

Here's a great tutorial that goes through EVERYTHING about classes.

http://www.hudzilla.org/phpbook/read.php/6_0_0

[ab4net]

now am wondering about some thing,
bretticus;
in your example in the last post, you have created a connection method to a database, and called this to the every page connects to a database ...
now why dont we use the file : db.inc as example which contains the normal connection method ...
and then when we want to use it we just have to do :
include("db.inc");
even it is less writing in the pages, and less bytes ..?

or you have some thing else to explain to me ..

thanks in advance ..

[bretticus]

You are certainly welcome to use procedural coding here and simply insert the include file code. However, what if you want to make some useful methods (functions) in your database class? If you did, they could be called and you would never need to worry about database connections to associate, etc. In other words, I instantiate my db class with the credentials and host info (another reaon a class coudl be nice in this case.) Say you have a getrows method (similiar to the one used for MS ADO with ASP.) Now you just have to call $db->getrows("SELECT * FROM table") and you'll get back your array all nice and neat and all you ever had to do was call a new Database class with the proper arguments. You can even call multiple db classes within your script and their variables will never "cross"

[ab4net]

hmm , i think i understand some thing, correct me please ..
when we creates the database connection class,
we can also at the same time, define functions in it, such as getrows, lastinsertedrowid, deleterow, etc...
so when we want to do any query to the database we can just do:

$db = new dbclass;
$statement="SELECT * FROM table";
$db->getrows($statement);

is that right ..? or correct me please ...

thanks alot,

[Weedpacket]

Originally posted by ab4net

is that right ..?

yep, that's right. Instead of having to do everything using the functions that have been given to you (mysql_query, mysql_result, mysql_num_rows) (and having the fun of finding them all and replacing them if you change DBMSs) you can write something that provides the functions that you will actually want (like getrows) and you will be able to use them without having to deal with the rude mechanicals of handling the database connection (or even, if the class is elaborate enough, the SQL itself can be hidden behind something a bit more appropriate) because those are all being handled within the object.

[bretticus]

Weedpacket brings up a very good point. I actually do have a database class that I use frequently. And the purpose of it was to be able to use postgres (haven't written that side of it yet) and MySQL while using the same PHP code. All I will have to do is create a variable (better known as a property in classes) that I can reference within the class to decide whether to do internal or hidden work within my class for PostGreSQL or MySQL. The beauty if that my PHP code where I call it will never now the difference 'cause my methods are uniform.

You bring up a good point that people can get carried away with classes. Obviously, with my example, It's just as easy to have an include statement to drop in somtimes 😃 However, if you are building something where you anticipate using repetitive functions, etc. classes can facilitate your coding significantly.

Here's a sample of code that I have written today using a couple of different classes. It won't make too much sense, but hopefully I have implemented my class methods in a way that, symantically, makes the code easy to read and demonstrate the convenience that coding with classes can provide:

$forms->validateInput("txtClientName", REXP_EMPTY, "Client Name cannot be blank.");
					$forms->validateInput("txtAddress", REXP_EMPTY, "Address cannot be blank.");					
					$forms->validateInput("txtCity", REXP_EMPTY, "City cannot be blank.");
					$forms->validateInput("txtPhone", REXP_EMPTY, "Phone cannot be blank.");
					$forms->validateInput("txtFirstName", REXP_EMPTY, "Contact Firstname cannot be blank.");
					$forms->validateInput("txtLastName", REXP_EMPTY, "Contact Lastname cannot be blank.");
					$forms->validateInput("txtEmail", REXP_EMAIL, "Contact Email is blank or invalid.");		
					if (!$forms->hasFormErrors()) {
						/*** INSERT CLIENT ***/
						$pm->data->add_insert("Client", trim($_POST['txtClientName']));
						$pm->data->add_insert("RenewalMonth", trim($_POST['mnuRenewalMonth']));
						$pm->data->add_insert("SalesPerson", trim($_POST['mnuSalesperson']));			
						if ($_POST['chkAssocParent'] == "yes")
							$pm->data->add_insert("ParentID", $_POST['mnuParentClient']);
						if ($_POST['chkBillParent'] == "yes")
							$pm->data->add_insert("BillParent", 1);
						$clientId = $pm->data->exec_insert("Clients");
						/*** INSERT CLIENT ADDRESS ***/
						$pm->data->add_insert("ClientID", $clientId);
						$pm->data->add_insert("AddressType", "billing");
						$pm->data->add_insert("Address", trim($_POST['txtAddress']));
						$pm->data->add_insert("Address2", trim($_POST['txtAddress2']));
						$pm->data->add_insert("City", trim($_POST['txtCity']));
						$pm->data->add_insert("State", trim($_POST['mnuState']));
						$pm->data->add_insert("Postal", trim($_POST['txtPostalCode']));
						$pm->data->add_insert("Country", trim($_POST['mnuCountry']));
						$pm->data->exec_insert("ClientAddresses");
						/*** INSERT CLIENT PHONE ***/
						$pm->data->add_insert("ClientID", $clientId);
						$pm->data->add_insert("PhoneNumber", trim($_POST['txtPhone']));
						$pm->data->add_insert("PhoneType", "business");
						$pm->data->exec_insert("ClientPhones");
						/*** INSERT CLIENT FAX ***/
						$pm->data->add_insert("ClientID", $clientId);
						$pm->data->add_insert("PhoneNumber", trim($_POST['txtFax']));
						$pm->data->add_insert("PhoneType", "fax");
						$pm->data->exec_insert("ClientPhones");
						/*** INSERT PERSON ***/
						$pm->data->add_insert("FirstName", trim($_POST['txtFirstName']));
						$pm->data->add_insert("LastName", trim($_POST['txtLastName']));
						$personId = $pm->data->exec_insert("People");
						/*** INSERT PERSON EMAIL***/
						$pm->data->add_insert("PersonID", $personId);
						$pm->data->add_insert("Email", trim($_POST['txtEmail']));
						$pm->data->exec_insert("PersonEmails");
						/*** MAKE PERSON-CLIENT ASSOCIATION ***/
						$pm->data->add_insert("ClientID", $clientId);
						$pm->data->add_insert("PersonID", $personId);
						$pm->data->exec_insert("ClientPersons");
						/*** FEEDBACK OR REDIRECT ***/				
						if (!headers_sent()) {
							header("Location: /clientslist.php");
							exit();
						} else {
							$feedBack = "Client added successfully.";
						}
					}

[ab4net]

Thanks alot guys ...
am using now classes 🙂

it is really lot better ...

many thanks for you and for this good website ...

😃

[ab4net]

now i have some troubles here, i have tried to create a class to make a connection to database is OBJECT and to pass the host name and username and pass ... and handle some processing, as well as to select a certain database, and to do a query ...

hmmm ... i think i have did some thing wrong, and may be correcting me in here, and telling me what was my mistake and where will complete making me understanding the class 😃 i thank you really, and dont know what to do without you guys ..

here is what i have wrote in the class :

<?php
class db {
        var $thehost;       #Host Name
        var $theusername;   #the username of the database connection
        var $pass;          #the password of the connection
        var $dbcon;         #to connect to database FALSE or TRUE
        var $dbs;           #to select a database
        var $dbno;          #if failed to connect to database the value is 1
        var $dbsno;         #if failed to select database the value is 1
        var $statement;     #the MySQL statement
        var $query;         #doing the MySQL query
        var $qno;           #if query is not okkay it gets the value 1
        # the function to connect to database
        function connectdb($this->thehost,$this->theusername,$this->pass)
        {
         $this->dbcon=@mysql_connect($this->thehost,$this->theusername,$this->pass);
         if (!$this->dbcon){
         echo("Unable to connect to Database .. Call webmaster");
         $this->dbno=1;
         }else{
             $this->dbno=0;
         }
        }
        # the function to select to database
        function selectdb()
        {
         $this->dbs=mysql_select_db("ab4net");
         if (!$this->dbs){
         echo("Error Sellecting DB .. Call webmaster");
         $this->dbsno=1;
         }else{
             $this->dbsno=0;
         }
        }
        # the function to process the query
        function getresult($this->statement,$this->dbcon)
        {
         $this->query=mysql_query($this->statement,$this->dbcon);
         if(!$this->query){
         echo("Error in SQL Statement .. Call webmaster<br>");
         echo mysql_error()\n;
         $this->qno=1;
         }else{
             $this->qno=0;
         }
        }


}
?>

please advice ...

thanks alot .. .

[bretticus]

The $this variable is a built-in object pointer to the class within itself. In other words, you do not need to pass these variables as arguments for your class implementation (it's wrong to do so also.) Any arguments in your methods will never use the $this->variable notation. As you get used to classes it will make crystal clear sense in time. Any arguments will be used solely in that method (as they should). In other words, you can't replace arguments with variables in function and this is no different in a class. The following code should work a bit smoother:

class db {
        var $thehost;       #Host Name
        var $theusername;   #the username of the database connection
        var $pass;          #the password of the connection
        var $dbcon;         #to connect to database FALSE or TRUE
        var $dbs;           #to select a database
        var $dbno;          #if failed to connect to database the value is 1
        var $dbsno;         #if failed to select database the value is 1
        var $statement;     #the MySQL statement
        var $query;         #doing the MySQL query
        var $qno;           #if query is not okkay it gets the value 1
        # the function to connect to database
        function connectdb()
        {
         $this->dbcon=@mysql_connect($this->thehost,$this->theusername,$this->pass);
         if (!$this->dbcon){
         echo("Unable to connect to Database .. Call webmaster");
         $this->dbno=1;
         }else{
             $this->dbno=0;
         }
        }
        # the function to select to database
        function selectdb()
        {
         $this->dbs=mysql_select_db("ab4net");
         if (!$this->dbs){
         echo("Error Sellecting DB .. Call webmaster");
         $this->dbsno=1;
         }else{
             $this->dbsno=0;
         }
        }
        # the function to process the query
        function getresult()
        {
         $this->query=mysql_query($this->statement,$this->dbcon);
         if(!$this->query){
         echo("Error in SQL Statement .. Call webmaster<br>");
         echo mysql_error()n;
         $this->qno=1;
         }else{
             $this->qno=0;
         }
        }


}

$db = new db();
$db->thehost = "localhost";
$db->theusername = "user";
// ... set more properties before you call ...
$db->connectdb();

[ab4net]

thanks alot ...
this is so helpful 🙂

i'll work on it, and get back to you if troubles there ..

thanks alot alot alot ...

😃

[ab4net]

hi,
please ...

i'll be so greatful if you have a look on the other thread and help me out there ...

http://www.phpbuilder.com/board/showthread.php?s=&threadid=10296809

thanks in advance ...