Catch My Fame

In the years that I’ve been a web developer, I have written very few OOP PHP scripts. I just haven’t had the need to, and to be honest the whole OOP concept seemed like something I didn’t need to bother with. Why do I need to write a script in an object-oriented style and how will it help me? I had seen examples and read tutorials about OOP (some horribly bad and some really good) but never had any desire to try it myself until one day when I was working on a couple of different projects that both needed the same thing, pagination.

Pagination just means numbering pages. In the project that I was working on, I was retrieving large amounts of data from a MySQL database and realized that I would have to break the data up into pages for two main reasons, 1) there was so much data that it could hang the browser when it was loading and 2) from a user perspective (we still care about that right?) it was unruly to say the least. If I was returning 50,000 rows from a database query, I knew that I would need to slice that up into more manageable chunks. Now in the past, I had written basic pagination functions to handle this type of issue and sometimes copied and pasted functions from older scripts to cut down on development time, fixing and re-coding where necessary. But I realized that for this new project I could try to write a pagination class that I would be able to just plug into any script and have it do the pagination for me. I could write a pagination class that I could use for my projects and future projects, and learn OOP in the process. I love killing two birds with one stone.

Which brings me to our pagination class (paginator.class.php). Now I’m not claiming to be the first person to write a pagination class — far from it. But I do feel that this one is the most lightweight, feature-rich, and easy to use that I’ve seen. For an example of the pagination class in action, click here. To download the pagination class, click here.

In the example below, you can see the paginator used at the top and bottom of the database query.

In this example, you can see the mid range property which creates a range of pages around the current page and the use of … to distinguish the break between contiguous pages

In this example you can see the optional items per page drop down menu

In this example you can see the optional page jump menu

In this example we see how the previous and next buttons are sensitive to what the current page is.

This example shows how when there are less than 11 pages to display that the previous, next, and all links are not shown

This example shows an alternate styling of the pagination results. By default a Digg-like CSS scheme is used however you can style the menu in limitless ways

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Paginator.class.php

The paginator class allows you to easily generate page numbers and restrict database results without having to create complex pagination code of your own.

Features:

• Easy to use and reuse.
• Dynamically creates page numbers based on the total number of items in a query and the desired number of items per page.
• Ability to select a number of pages to display around the currently select page.
• Links to show all results instead of paginated results.
• Easily styled via CSS.
• Returns SQL which can be used to modify the results in query.
• The items per page can be changed by the user using a build in method which generates a simple drop down menu.
• A ‘jump to page’ menu can be generated to give the user quick access to jump to any page of the results.
• Creates ‘previous’ and ‘next’ buttons when more than 10 pages are generated.

Properties:

• $items_per_page – The desired number of items to be shown on a page. Can be set by the script author or user
• $items_total – The total number of items you’ll be paginating. Typically set by querying a table for a count of rows
• $current_page – The page the user is viewing. Will always be an integer > 1
• $num_pages – The total number of pages as generated by the paginator method
• $mid_range – The number of pages to show ‘around’ the current page. See step 5 in How To Use below
• $low – The offset to use in a SQL LIMIT statement (e.g. SELECT * FROM employees LIMIT 20,10)
• $high – The number of rows to select in a SQL LIMIT statement (e.g. SELECT * FROM employees LIMIT 20,10)
• $limit – A string used in an SQL statement to automatically handle the limiting of results based on the current page of results
• $return – A string used to store the HTML containing the page numbers.
  Used in the display_pages method
• $default_ipp = 25 – The default number of items to display per page

Methods:

• Paginator
  Constructor. Usage: $pages = new Paginator;
• paginate
  Calculates pages to display. Usage: $pages->paginate();
• display_items_per_page
  Returns a string of HTML used to display an items per page menu. Usage: echo $pages->display_items_per_page();
• display_jump_menu
  Returns a string of HTML used to display a page jump menu. Usage: echo $pages->display_jump_menu();
• display_pages
  Returns a string of HTML used to display the pages generated by the paginator method. Usage: echo $pages->display_pages();

How to use:

1. Include paginator.class.php at the top of your script
   code: require_once ‘paginator.class.php’;
   Note: You could use include(), include_once(), or require() however using require_once ensures that the class will only be included once and if it can’t be found, will cause a fatal error.
2. Set the total number of items that you’ll be paginating. There are two ways to do this, 1) you can hard code the total, but that’s unrealistic since you’ll probably be using this class to paginate a database anyway (the whole point no?) but it can be a convenient way of testing or 2) make a quick call to your database to count the items you’ll be paginating. Ex: ‘SELECT COUNT(*) FROM table’ and save the total in a variable for use in step 4.
3. Create a new Paginator object.
   code: $pages = new Paginator;
4. Set the total items property of this new Paginator object.
   code: $pages->items_total = X where X is the total from see step 2
5. Set the mid range property. The mid range is the number of pages that the paginator will display, centered around and including the selected page. For example, if the mid range is set to seven ($pages->mid_range = 7;) then when browsing page 50 of 100, the mid range generates links to pages 47, 48, 49, 50, 51, 52, and 53. The mid range moves in relation to the selected page. If the user is at either the low or high end of the list of pages, it will slide the range toward the other side to accommodate the position. For example, if the user visits page 99 of 100, the mid range will generate links for pages 94, 95, 96, 97, 98, 99, and 100.
   code: $pages->mid_range = X; where X is odd and >=3. The default mid_range property is 7.
6. That’s all for the configuration, now you can generate page numbers. To paginate, call the pagination method ($pages->paginate();). This generates no output so to show the page numbers call the display method ($pages->display_pages();). You MUST call the paginate method before calling the display method. You can call the display method more than once which can be handy for display page numbers both above and below a result set.
7. Optionally, you can give the visitor features in addition to what is provided by the display method.
   1. A drop down page jump menu is available via the display_jump_menu method ($pages->display_jump_menu();). This is a simple select menu that lists all page numbers. When a user changes the page number, the page will automatically switch to the selected page.
   2. A drop down items per page menu is available via the display_items_per_page method
      ($pages->display_items_per_page();). This select menu allows visitors to change the number of items that are displayed on a page. By default, the list it generates is 10, 25, 50, 100, All. You can modify the class if needed to allow for other options however the All options is case-sensitive.
8. Once the paginate method has been called (see step 6), you can execute your db query to fetch the limited result set (or all results). Paginate creates the SQL used to limit results automatically so you can edit your query to take advantage of this. For example, if your query before pagination was “SELECT id, name, address FROM table ORDER BY id ASC”, you would change it to be “SELECT id, name, address FROM table ORDER BY id ASC $pages->limit”. When a user selects the ‘All’ option, they effectively set $pages->limit to nothing and any page selected automatically creates the appropriate limit.
   code: $pages->limit
9. Styles. The pagination class has been created so that it can be styles with CSS easily. The recommended CSS is:
   <style type=”text/css”>
   .paginate {
   font-family: Arial, Helvetica, sans-serif;
   font-size: .7em;
   }
   a.paginate {
   border: 1px solid #000080;
   padding: 2px 6px 2px 6px;
   text-decoration: none;
   color: #000080;
   }
   a.paginate:hover {
   background-color: #000080;
   color: #FFF;
   text-decoration: underline;
   }
   a.current {
   border: 1px solid #000080;
   font: bold .7em Arial,Helvetica,sans-serif;
   padding: 2px 6px 2px 6px;
   cursor: default;
   background:#000080;
   color: #FFF;
   text-decoration: none;
   }
   span.inactive {
   border: 1px solid #999;
   font-family: Arial, Helvetica, sans-serif;
   font-size: .7em;
   padding: 2px 6px 2px 6px;
   color: #999;
   cursor: default;
   }
   </style>
10. Basic example:
    <!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN”
    “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>
    <html xmlns=”http://www.w3.org/1999/xhtml”>
    <head>
    <meta http-equiv=”Content-Type” content=”text/html; charset=iso-8859-1″ />
    <title>Paginator</title>
    <style type=”text/css”>
    .paginate {
    font-family: Arial, Helvetica, sans-serif;
    font-size: .7em;
    }
    a.paginate {
    border: 1px solid #000080;
    padding: 2px 6px 2px 6px;
    text-decoration: none;
    color: #000080;
    }
    a.paginate:hover {
    background-color: #000080;
    color: #FFF;
    text-decoration: underline;
    }
    a.current {
    border: 1px solid #000080;
    font: bold .7em Arial,Helvetica,sans-serif;
    padding: 2px 6px 2px 6px;
    cursor: default;
    background:#000080;
    color: #FFF;
    text-decoration: none;
    }
    span.inactive {
    border: 1px solid #999;
    font-family: Arial, Helvetica, sans-serif;
    font-size: .7em;
    padding: 2px 6px 2px 6px;
    color: #999;
    cursor: default;
    }
    </style>
    </head>
    <body>
    <?php
    require_once ‘paginator.class.php’;
    // Make your database connection here and retrieve your total number of
    items (i.e. SELECT COUNT(*) FROM…)
    $pages = new Paginator;
    $pages->items_total = $db_count;
    $pages->mid_range = 7;
    $pages->paginate();echo $pages->display_pages();
    // Make your db query here. Include $pages->limit as described in step 8.
    (i.e. SELECT id,fname,lname FROM employees $pages->limit)
    echo $pages->display_pages(); // Optional call which will display the pages
    number after the results.
    echo $pages->display_jump_menu(); // Optional – displays the page jump menu
    echo $pages->display_items_per_page(); //Optional – displays the items per
    page menu
    ?>
    </body>
    </html>

All in all you could add pagination to any database driven set of results with about five lines of code. To display the current page number in the format ‘Page X of Y’ where X is the current page and Y is the total number of pages, use the code: echo “<p class=\”paginate\”>Page: $pages->current_page of $pages->num_pages</p>\n”;. To display the SQL that was generated, use the code: echo “<p class=\”paginate\”>SELECT * FROM table $pages->limit (retrieve records $pages->low-$pages->high from table – $pages->items_total item total / $pages->items_per_page items per page)”;