Updated book PHP Tutorials: Programming with PHP and MySQL

Posted on April 25, 2020 by Paul Gibbs

The eBook and Physical Book PHP Tutorials: Programming with PHP and MySQL has been recently updated to include new examples, expanded code explanations and updated material. In particular:

* The removal of code and descriptions only relevant to PHP versions earlier than
PHP 7.
* Expansion of code examples.
* More explanation of code as used for connecting to databases using PDO and mysqli.
* Further details in data validation.
* Best coding principles and practices.
* Plus many other changes.

US Web site

UK Web Site

Bootstrap 4 NavBar make Rollover for DropDown Navigation and Clickable Top Link

Posted on October 22, 2019 by Paul Gibbs — No Comments ↓

This explains how to change the default Bootstrap 4 NavBar so that any drop down is activated by a mouse rollover rather than an on-click. It also shows how to change the top level navigation link to be clickable.

The default behaviour of the Bootstrap 4 navigation is any drop down has to be clicked for the drop down to work. The Bootstrap version that I am currently using is version 4.3 which you can see at:

https://getbootstrap.com/docs/4.3/components/navbar/#supported-content

If you look at the given example, part of the navbar is the drop down code:

 <li class="nav-item dropdown">
        <a class="nav-link 
                  dropdown-toggle" 
                  href="#" 
                  id="navbarDropdown" 
                  role="button" 
                  data-toggle="dropdown" 
                  aria-haspopup="true" 
                  aria-expanded="false">
          Dropdown
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>

To allow mouse rollover, add in the following styles as follows:

<style>
.dropdown:hover .dropdown-menu {
display: block;
}
</style>

Now remove the line data-toggle=”dropdown” in the dropdown code which will make the top link clickable.

So that should be that. Now a mouse rollover will cause the drop down to appear, and the top link is clickable.

A Shopping Cart using PHP Sessions

Posted on August 16, 2019 by paulv — No Comments ↓

This posts illustrates a relatively simple shopping cart in PHP using sessions to store cart details, quantities and total cart amount. The cart has an add to cart button , remove from cart button and displays the total value of the cart.

This post is taken from part of the book PHP Tutorials: Programming with PHP and MySQL which is available as a paper back printed version or as a downloadable Kindle version. Click here for paper back version.

The following listing is the complete shopping cart in PHP:

<?php session_start();
#cart.php - A simple shopping cart with add to cart, and remove links
 //---------------------------
 //initialize sessions

//Define the products and cost
$products = array("product A", "product B", "product C");
$amounts = array("19.99", "10.99", "2.99");

//Load up session
 if ( !isset($_SESSION["total"]) ) {
   $_SESSION["total"] = 0;
   for ($i=0; $i< count($products); $i++) {
    $_SESSION["qty"][$i] = 0;
   $_SESSION["amounts"][$i] = 0;
  }
 }

 //---------------------------
 //Reset
 if ( isset($_GET['reset']) )
 {
 if ($_GET["reset"] == 'true')
   {
   unset($_SESSION["qty"]); //The quantity for each product
   unset($_SESSION["amounts"]); //The amount from each product
   unset($_SESSION["total"]); //The total cost
   unset($_SESSION["cart"]); //Which item has been chosen
   }
 }

 //---------------------------
 //Add
 if ( isset($_GET["add"]) )
   {
   $i = $_GET["add"];
   $qty = $_SESSION["qty"][$i] + 1;
   $_SESSION["amounts"][$i] = $amounts[$i] * $qty;
   $_SESSION["cart"][$i] = $i;
   $_SESSION["qty"][$i] = $qty;
 }

  //---------------------------
  //Delete
  if ( isset($_GET["delete"]) )
   {
   $i = $_GET["delete"];
   $qty = $_SESSION["qty"][$i];
   $qty--;
   $_SESSION["qty"][$i] = $qty;
   //remove item if quantity is zero
   if ($qty == 0) {
    $_SESSION["amounts"][$i] = 0;
    unset($_SESSION["cart"][$i]);
  }
 else
  {
   $_SESSION["amounts"][$i] = $amounts[$i] * $qty;
  }
 }
 ?>
 <h2>List of All Products</h2>
 <table>
   <tr>
   <th>Product</th>
   <th width="10px">&nbsp;</th>
   <th>Amount</th>
   <th width="10px">&nbsp;</th>
   <th>Action</th>
   </tr>
 <?php
 for ($i=0; $i< count($products); $i++) {
   ?>
   <tr>
   <td><?php echo($products[$i]); ?></td>
   <td width="10px">&nbsp;</td>
   <td><?php echo($amounts[$i]); ?></td>
   <td width="10px">&nbsp;</td>
   <td><a href="?add=<?php echo($i); ?>">Add to cart</a></td>
   </tr>
   <?php
 }
 ?>
 <tr>
 <td colspan="5"></td>
 </tr>
 <tr>
 <td colspan="5"><a href="?reset=true">Reset Cart</a></td>
 </tr>
 </table>
 <?php
 if ( isset($_SESSION["cart"]) ) {
 ?>
 <br/><br/><br/>
 <h2>Cart</h2>
 <table>
 <tr>
 <th>Product</th>
 <th width="10px">&nbsp;</th>
 <th>Qty</th>
 <th width="10px">&nbsp;</th>
 <th>Amount</th>
 <th width="10px">&nbsp;</th>
 <th>Action</th>
 </tr>
 <?php
 $total = 0;
 foreach ( $_SESSION["cart"] as $i ) {
 ?>
 <tr>
 <td><?php echo( $products[$_SESSION["cart"][$i]] ); ?></td>
 <td width="10px">&nbsp;</td>
 <td><?php echo( $_SESSION["qty"][$i] ); ?></td>
 <td width="10px">&nbsp;</td>
 <td><?php echo( $_SESSION["amounts"][$i] ); ?></td>
 <td width="10px">&nbsp;</td>
 <td><a href="?delete=<?php echo($i); ?>">Delete from cart</a></td>
 </tr>
 <?php
 $total = $total + $_SESSION["amounts"][$i];
 }
 $_SESSION["total"] = $total;
 ?>
 <tr>
 <td colspan="7">Total : <?php echo($total); ?></td>
 </tr>
 </table>
 <?php
 }
 ?>

The cart example uses the following sessions to maintain the state of the cart:

$_SESSION[“qty”][i] Stores the quantity for each product
$_SESSION[“amounts”][i] Stores the price from each product
$_SESSION[“cart”][i] Identifies which items have been added to the cart
$_SESSION[“total”] Stores the total cost

The sessions are actually arrays so in the case of:

$_SESSION[“qty”][i]

is the quantity for the element with number i.

Description of the PHP shopping cart code

We start by defining PHP to use sessions by:

session_start();

This has to be at the very top of the PHP page.

Next we set up our products and populate our sessions. In this example we are using a fixed array of product descriptions and amounts. You may want to do this in your application or you could read in the data into the $product and $amounts array from a database.

//---------------------------
 //initialise sessions

 //Define the products and cost
 $products = array("product A", "product B", "product C");
 $amounts = array("19.99", "10.99", "2.99");

 if ( !isset($_SESSION["total"]) ) {

  $_SESSION["total"] = 0;

  for ($i=0; $i< count($products); $i++) {
   $_SESSION["qty"][$i] = 0;
   $_SESSION["amounts"][$i] = 0;
 }
}

The following code will reset and clear the sessions when the Reset Cart link is selected.

//---------------------------
  //Reset
  if ( isset($_GET['reset']) )
   {
    if ($_GET["reset"] == 'true')
    {
     unset($_SESSION["qty"]); //The quantity for each product
     unset($_SESSION["amounts"]); //The amount from each product
     unset($_SESSION["total"]); //The total cost
     unset($_SESSION["cart"]); //Which item has been chosen
   }
}

The following code adds an item to the sessions when the ‘Add to Cart’ link is clicked:

//---------------------------
//Add
if ( isset($_GET["add"]) )
{
$i = $_GET["add"];

$qty = $_SESSION["qty"][$i] + 1;

$_SESSION["amounts"][$i] = $amounts[$i] * $qty;
$_SESSION["cart"][$i] = $i;
$_SESSION["qty"][$i] = $qty;
}

and the following deletes an item from the cart when the ‘Delete from Cart’ link is clicked:

 //---------------------------
 //Delete
 if ( isset($_GET["delete"]) )
 {
   $i = $_GET["delete"];
   $qty = $_SESSION["qty"][$i];
   $qty--;
   $_SESSION["qty"][$i] = $qty;

 //remove item if quantity is zero
 if ($qty == 0) {
   $_SESSION["amounts"][$i] = 0;
   unset($_SESSION["cart"][$i]);
 }
 else
 {
   $_SESSION["amounts"][$i] = $amounts[$i] * $qty;
 }
 }

The rest of the code is the visual display using a table and various loops to show the product lists and the cart details together with the links.

PHP-eSeller is a complete application that utilizes a shopping cart using PHP Sessions and is available from here:

Click here to go to PHP-eSeller web page

Using Subversion for WordPress Plugins

Posted on January 7, 2018 by Paul Gibbs — No Comments ↓

Subversion Control for WordPress

If you write a plugin for WordPress and want to make it available on WordPress.org, you have to use Subversion to handle revisions, versions and source control.

There are a number of programs that you can use and which can be installed on a PC or a MAC. Many do use the command line which can be difficult for those not familiar with the particular commands. However, there are a number of client applications that have very good user interfaces which does make the process much easier.

SilkSVN Windows Command Line Client. https://sliksvn.com/download/
TortoiseSVN for Windows which can be downloaded at https://tortoisesvn.net/downloads.html
Versions for the Mac which can be downloaded at http://versionsapp.com

When I first began to look at WordPress and SVN, I wanted to use a visual method of updating. I wanted to click a button and for it to automatically do everything without thinking. However, I found that using a visual interface did not show the point of SVN and when I started to use a text interface, I found I understood the process much better. Also there is a lot of documentation available for the command line interface which is helpful when things go wrong.

The following are some notes that I have made over the years about using the command line system with WordPress which may help if you are having issues. It is based on the WordPress.org documentation but I have added in some extra points.

Command Line SVN

As I use Windows I use SilkSVN. Download and install SilkSVN and in the cmd terminal (go to Windows Start and enter cmd.exe), type “svn” followed by the required commands. “svn help” will show help text and will show that SilkSVN is working.

The documentation that WordPress has produced is located here:

https://developer.wordpress.org/plugins/wordpress-org/how-to-use-subversion/

The only issue I have found when using SilkSVN is that you should use double quotes wherever it uses single quotes as in the standard SVN documentation.

Also, always make sure you change directory to where your local repository is located.

Starting a new plugin

On your computer, first create a local directory which will be your copy of the SVN repository.

In this document I will use my-local-dir to refer to the local directory.

Next, check out the pre-built repository using the co command:

my-local-dir / svn co https://plugins.svn.wordpress.org/your-plugin-name my-local-dir
> A my-local-dir/trunk
> A my-local-dir/branches
> A my-local-dir/tags
> Checked out revision 11325.

You will probably be asked your username and password which will be the one you were given when you registered for WordPress.org.

The above command will create a set of folders on your local computer in your local directory called “trunk”, “branches” and “tags”.

The “tags” folder is for your releases and will consist of a number of sub folders that correspond to your version numbers.

The “trunk” folder is where your development version is located.

Copy your files into the “trunk” folder and then you have to let subversion know you want to add the files into the repository:

my-local-dir / svn add trunk/*

Now check in the changes:

my-local-dir / svn ci -m "Check in to trunk"

Now copy the trunk files to the required tag folder. In this example I am going to create a folder 1.0.0

my-local-dir / svn cp trunk tags/1.0.0
> A tags/1.0.0

and commit the changes:

my-local-dir / svn ci -m "tagging version 1.0.0"

So now on the remote repository you should have your released files in the tag/1.0.0 and your current working development files will also be in the “trunk” folder.

Creating a new version

We want to create a new version of our plugin so we:
* Modify the readme.txt with the new version number.
* Modify the main php file with the new version number.
* Update the trunk folder so that it contains the latest files.
* Copy the trunk folder to a new tags folder using SVN.
* Check in the changes using SVN.

Essentially the method is the same as described above but with a few more checks.

On your local computer, make sure that your trunk files are up to date.

We can do this by using the SVN update command. (First, change your directory to where the SVN local directory is situated):

my-local-dir / svn update

Files in the remote repository are downloaded and update the local files.

Copy over the file or files to your local trunk folder and then let subversion know you want to add those files back:

my-local-dir / svn add trunk/*

Now commit the changes:

my-local-dir / svn ci –m “add new files to trunk”

Now do a status display:

my-local-dir / svn stat

You can see the meaning of the status information further at the end of this article.

At this point, you may have to delete files / folders by:

my-local-dir / svn delete

In some cases, you may have to use –force to force the deletion.

When you do:

my-local-dir / svn stat

you should now see those files/folders marked for deletion.

Deleting only deletes it form the local copy and only schedules if for deletion from the repository. You have to then commit the changes by:

my-local-dir / svn ci -m "New files update"
> Sending trunk/my-plugin.php
> Transmitting file data .
> Committed revision 11327.

That updates the files in the trunk folder and deletes any marked files.

Now that you have the files checked in to the trunk folder, you can copy over the files to a tag folder as described above.

You do this by:

my-local-dir / svn cp trunk tags/2.0
> A tags/2.0

Now, as always, check in the changes.

my-local-dir / svn ci -m "tagging version 2.0"
> Adding tags/2.0
> Adding tags/2.0/my-plugin.php
> Adding tags/2.0/readme.txt
> Committed revision 11328.

The assets folder

Use the assets folder for files like screenshots, banners and icons for wordpress.org site. Note that the assets folder is a separate folder in the root of the folder structure and is not a subfolder of the trunk or tag folder.

Update as the assets folder follows.

Navigate to the local folder which is the root of the SVN, then enter:

my-local-dir / svn add assets/*
>  A assets/sceenshot-1.png
>  A assets/sceenshot-2.png

The “add assets/*” identifies all files in the assets folder.

After you add all your files, you need to check in the changes back to the central repository using ci:

my-local-dir / svn ci -m “Add assets”
> Adding assets/screenshot-1.png
> Adding assets/screenshot-2.png
> Transmitting file data
> Committed revision 1124545

Status Command

A useful command is “svn status” which gives information about the state of the repository.

 my-local-dir / svn stat

If you see ? in the list of files or folders, it means that they are not under svn control. In which case do “svn add
To use this command as with all the other commands, you need to change directory on your local computer to the root folder of the SVN.

U: Working file was updated
G: Changes on the repository were automatically merged into the working copy
M: Working copy is modified
C: This file conflicts with the version in the repository
?: This file is not under version control
!: This file is under version control but is missing or incomplete
A: This file will be added to version control (after commit)
A+: This file will be moved (after commit)
D: This file will be deleted (after commit)
S: This signifies that the file or directory has been switched from the path of the rest of the working copy (using svn switch) to a branch
I: Ignored
X: External definition
~: Type changed
R: Item has been replaced in your working copy. This means the file was scheduled for deletion, and then a new file with the same name was scheduled for addition in its place.
L : Item is locked
E: Item existed, as it would have been created, by an SVN update.

Problems, problems, problems

If you get a message ‘folder name’ is scheduled for addition, but is missing then look at the following document:

https://benohead.com/svn-file-scheduled-addition-missing/

Also look at:

http://svnbook.red-bean.com/en/1.6/svn.ref.svn.c.delete.html

The method that I have found to use is rm (remove), or you may use the delete command. So you do something like:

my-local-dir / svn rm –force c:\csv\withinweb_wp_keycodes\withinweb-php-keycodes\tags\2.0.0\views

Once you have removed all the problems you should be able to commit.

Note that you may have change the local directory to the file or folder that you are going to delete or you have to enter the full path name of the file or folder.

Checking differences

Checking files are at the correct version can be done by doing a diff.

How to sell serial license keys for digital goods using PHP-KeyCodes

Posted on September 17, 2017 by Paul Gibbs — No Comments ↓

If you sell digital products online such as software programs, games, phone PIN numbers and so on, then PHP-KeyCodes can be a useful application to install on your web site. It requires a web server running PHP and access to a MySQL database. It is easy to install with a one page install script and upload of files to your server.

PHP-KeyCodes is not just limited to distributing software license keys, you can also be use it to distribute any kind of unique key code to a customer. This could be pin numbers for mobile phone applications, TV activation systems and serial key codes for any system where there is a list of pre-generated license key codes.

If you have a requirement to sell license codes on line then this is a better method than using someone else’s web site as you do not have to pay them any fees.

Using a license system for your software program helps to prevent fraud and allows you to send free trial versions to customers. The key codes are loaded into the PHP-KeyCodes web site administration interface so that they are automatically sent whenever there is a purchase using PayPal.

The system will also send you an email when it is getting low on license keys.

The usual way to use PHP-KeyCodes is to enter the codes into the admin area so that the next code in the list is taken and sent when there is a purchase.

The PHP script has been written in such a way as to allow you to modify the program to cover other situations. So for example you may have codes in a text file that you want to upload to the server. You could modify the code to use such a text file. You could even have code that generates a key code depending on the user name or email address.

If you have particular requirements, then we would be willing to customize the code for you.

For more information: PHP-KeyCodes

http://www.withinweb.com/phpkeycodes/

Adding a virtual directory (folder) to Apache XAMPP or similar application

Posted on December 18, 2015 by Paul Gibbs — No Comments ↓

Suppose that you have installed XAMPP at c:\xampp This will mean you place your web files at C:\xampp\htdocs

Now you want to start developing your project, so what you could do is copy all your files to the C:\xampp\htdocs or create another folder
such as C:\xampp\htdocs\myproject

However, this is not always convenient so how do you create an alias, leaving your files where they are.

First, open the httpd.conf file, it’s located in this directory:
C:\Program Files\xampp\apache\conf

You can access this from the XAMPP control panel by clicking the “config” button.

Add these lines on the bottom of the httpd.conf file:

Alias /sources “c:/myproject”

Options Indexes FollowSymLinks Includes ExecCGI
AllowOverride All
Order allow,deny
Allow from all
Require all granted

Note that in we must use “Forward Slash” or / in the folder definition

Restart XAMPP or stop and start Apache from the control panel.

Open your web browser and test it by go to http://localhost/myproject

Removing depreciated messages in PHP

Posted on May 25, 2013 by paulv — No Comments ↓

To remove depreciated messages form displays you can use the ~E_DEPRECATED value in the error_reporting function something like the following :

error_reporting(E_ALL & ~E_DEPRECATED & ~E_NOTICE);

Warning messages for depreciated functions

Posted on April 21, 2013 by paulv — No Comments ↓

In version PHP 5 there is a new warning state of E_STRICT

To remove there warning messages use :

error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT);

Depreciated functions still exist and you get the warning. So they work as expected. However in a future version they might disappear.

New PHP script to register users on your site

Posted on April 15, 2013 by paulv — No Comments ↓

PHP-Register is a new PHP / mySQL application that is used to easily create forms that collect data from your visitors before they are directed to a page of your choice.

The application is easy to instal on on Linux type web server or Windows web server providing it has PHP and mySQL.

In the administration pages you can create forms with each form having input boxes of text, textarea, drop down lists, checkboxes or radio buttons. Each input may have validation allowing you to define the data that a visitor can enter.

For full details, refer to http://www.withinweb.com/phpregister/

Using different PHP versions on your web site

Posted on March 13, 2013 by paulv — No Comments ↓

Sometimes it may be necessary to use a different version of PHP on a web folder rather than the default. This may be when you have an application that only works on later versions of PHP as it contains functions that only work on later versions of PHP.

On some web servers this can be done using AddHandler in an htaccess file in the folder that you want a different version of PHP in.

So for version PHP 5.1

AddHandler application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml
AddType application/x-httpd-php5 .php5 .php4 .php .php3 .php2 .phtml

You should check with your hosting to make sure that this will work of course.

General PHP