Categories
PHP Programming

Validate Email Addresses With PHP

If you’re a web programmer, there will come a time when you need to validate an email address. It’s going to happen, so just accept it. In newer versions of PHP, there is built in functionality for this. However, for those of us not lucky enough to be running the latest and greatest version, we can use regular expressions.

The following PHP function will validate email addresses using regular expressions. True is returned on success, and false is returned otherwise.

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function validate_email($email) {
return eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$", $email);
}
Categories
PHP Programming Wordpress Development

Simple WordPress Plugin Tutorial

Sometimes WordPress just doesn’t do what you want it to do.  When that happens, you turn to plugins for help.  But sometimes, the WordPress plugin repositories don’t have what you need either.  In those cases, it’s time to pull up your sleeves and get to work.  In this tutorial, I’m going to go through the process of creating a simple WordPress plugin from scratch.  I created this plugin as a proof of concept awhile ago, and thought that it would make a great learning tool now.

Step 1:  What are you’re making anyways?

This plugin does one thing only, and it does it well.  It will place a “Submit to Hacker News” button on all of your posts.  While this tutorial is only for a simple plugin, it could easily be extended to include other news aggregation services and social networks.


Step 2:  Creating the plugin.

Now that we know what we’re going to create, we need to create the plugin.  To do that, simply create a file called wp-hacker-news.php and then add the following to it.

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/*
* Plugin Name: WP Hacker News
* Version: 0.1
* Description: Adds a "Submit to Hacker News" button to your posts.
* Author: Jack Slingerland
* Author URI: https://re-cycledair.com/
* Plugin URI: https://re-cycledair.com/wp-hacker-news
*/

The lines above are all required for a WordPress plugin to function correctly.  Below is a quick run-through of what each of these means.

  • Plugin Name – This is the name of your plugin.  It is how it will appear in the WordPress back-end administration panels.
  • Version – The version number.  I always start a 0.1 to start, and then increment like 0.1.1 for small changes.
  • Description – This is the description of your plugin.  Feel free to be verbose here, as this is how people will know what your plugin does.
  • Author – This is you!  Put your name or the name of your team here.
  • Author URI – Your website.  In my case, I link it to https://re-cycledair.com.
  • Plugin URI – The web page for your plugin.  Here, I’m linking it to the original announcement I made for this plugin.

Step 3:  Creating a display function.

So you finally have a WordPress plugin.  That’s great and all, but it doesn’t do anything yet.  What you need now is to create a  function that displays the “Submit To Hacker News” link.  To do that, add this below the comment section:

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//Function to show the HN Link.
function WPHackerNews_link() {
     global $post;
     $link = urlencode(get_permalink($post->ID));
     $title = urlencode($post->post_title);
     $formattedLink = "
     <div style="float: right; margin-left: 10px; margin-bottom: 4px;">
          <a href="http://news.ycombinator.com/submitlink?u=$link&t=$title">
               <img src="https://re-cycledair.com/wp-content/uploads/2010/03/hn.jpg" alt="" />
          </a>
          <span style="font-size: 9px;">
               <a href="http://news.ycombinator.com/submitlink?u=$link&t=$title">Submit to HN</a>
          </span>
          <a href="http://news.ycombinator.com/submitlink?u=$link&t=$title"></a>
     </div>
";
 
     return $formattedLink;
}

The code above explains itself pretty well.  But I’ll break it down a bit anyways.

  1. We set the global post variable.  It holds all of the information about the post we’re currently on.
  2. Store the current post’s permalink and title in variables.
  3. Using some in-line css and good old HTML, we get the Y Combinator logo to float on the right side of the post.
  4. Return the HTML for the button to the caller of the function.


Step 4:  Displaying your plugin.

Everything is going great, but now we need this to actually show up in posts.  To do that, we register a display function with WordPress.  With a bit of logic, we can make it only display on posts.

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//Integrate with Wordpress.
function WPHackerNews_ContentFilter($content) {
     if(is_single()) {
          return WPHackerNews_link().$content;
     } else {
          return $content;
     }
}
 
//Add the filter
add_filter ('the_content', 'WPHackerNews_ContentFilter');

The above code isn’t self-explanatory at all, so here’s how it works.

  1. When we create the function, we make sure to pass it “$content”.  “$content” is a variable that holds the content of the post that the user is on.
  2. We then check to make sure that we are on a single post with the function “is_single()”.
  3. If so, we return our button by calling “WPHackerNews_link()” and appending “$content” to it.
  4. If not, just return the original un-altered content.
  5. The final step is to use the “add_filter” function to add this plugin into WordPress.  The first argument describes where our plugin should be used (“the_content”), and the second argument is what function it should use (“WPHackerNews_contentFilter”).

Step 5:  You’re Done!

That concludes this tutorial on creating a simple WordPress plugin.  All you need to do now is drop this file in your wp-content/plugins directory and then activate it in the admin.  As usual, if you run in to any errors or notice any problems, please let me know and I’ll help the best I can.

Categories
Wordpress Development

Displaying a WordPress Widget on Specific Pages

Sometimes when you a creating a WordPress site or blog, you only want a widget to show up on specific pages or page types.  This used to be needlessly difficult, where you would need to edit your theme manually for it to work.  However, there is a new(ish) plugin called Widget Context, which allows you to pick specific pages or page types on which you would like a widget to be shown.

Wordpress Widget on Specific Pages

This plugin is WordPress 3 compatibile, and can be downloaded at http://wordpress.org/extend/plugins/widget-context/.

Categories
PHP Programming

PHP Validate Email

Every so often (ok, a lot more than that), you need to validate an email address. The obvious solution is to use regular expressions, however PHP provides a better method using the filter_var() function.

To validate an email address using PHP, simply do the following:

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$email = "jack@re-cycledair.wploadtest.xyz";
if(filter_var($email, FILTER_VALIDATE_EMAIL) == TRUE) {
     echo "Valid Email.";
} else {
     echo "Email is not valid.";
}

Note: This only works for PHP >= 5.2

Categories
PHP Programming Wordpress Development

WordPress 3 Custom Post Type Meta Box Tutorial

In my previous article, I talked about how to set up a rudimentary custom post type in WordPress 3.  This time, I’m going walk you through adding your own custom meta boxes to the admin interface.

Wordpress 3 Custom Post Type Meta Box

Step 1:  Add Meta Box (add_meta_box)

Out of the entire tutorial, this is probably the easiest part.  We’re going to add a little side-column box for “Thought of the Week”.

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add_meta_box("thought_of_the_week-meta", "Thought Of The Week", "thought_of_the_week", "newsletter", "side", "low");
  • Arguments
    • The first argument in add_meta_box is a unique identifiable string.  Try to user something descriptive.  In this case, I chose “thought_of_the_week-meta”.
    • The second argument is the title for the box that is going to show up.  Once again, be descriptive so the end user doesn’t have to guess at this.
    • The third argument is the function that displays your box information.
    • The fourth argument is the custom post type that you want this box to show up with.
    • The fifth argument is where you want the box.  I wanted it on the side, so I entered “side”.
    • The last argument is the priority of the box.  If you want it to appear lower on the post type, just enter “low”.  Else, you can add “high”.

Step 2: Display function & Get Post Meta (get_post_meta)

The next step is to create your display function.  Here’s mine.

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function thought_of_the_week(){
     global $post;
     $meta = get_post_meta($post->ID, 'thought_of_the_week', true);
     echo '<textarea name="thought_of_the_week">'.$meta.'</textarea>';
}

First, you need to declare the “$post” global variable.  This will give you access to a bunch of information, most important of which is the post ID.  In the second line, I get any saved meta information with the name “thought_of_the_week” (more on this later).  In the last line, I simply echo out a text area with the content from “get_post_meta”.

Step 3:  Saving Your Meta Information (add_action)

This step is easy as well.  Here you will register a save action with your custom post type.  All that means is that when you click the “Publish” or “Save Draft” button, this function will be called.

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add_action("save_post", "save_details");

The first argument is an action (more about actions here) which determines what action the second argument should be attached to.  The second argument is the function to get executed.  I called mine “save_details”.

Step 4:  Save the Details (update_post_meta)

The final step in creating a custom metabox in WordPress 3 is using the “update_post_meta”.

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function save_details($post_id) {
     global $post;
 
     if(isset($_POST['post_type']) && ($_POST['post_type'] == "newsletter")) {
          $data = $_POST['thought_of_the_week'];
          update_post_meta($post_id, 'thought_of_the_week', $data);
     }
}

Here’s a quick breakdown of this function.

  1. Declare the global “$post” variable.
  2. Check to see if the post type “newsletter” (or whatever your custom post type is named.
  3. Get the data out of the POST.
  4. Call update_post_meta().

The first argument in update_post_meta is the post ID.  The second is the name of the meta box.  The third is the data you wish to save.

Step 5:  That’s it!

That’s all there is to it.  Once you’ve done that, you can fetch the data anytime that you like by calling

Categories
PHP Programming Wordpress Development

WordPress 3 Custom Post Type Tutorial

When WordPress 3.0 was released, all the hype was about something called “custom post types”.  Custom post types basically allow you to add your own content types to WordPress.  Lets say for instance that you want to create a newsletter.  A newsletter in your case, is a quick descriptions followed by the excerpts from several regular posts.  By default, WordPress doesn’t support this.  However, with custom post types we can add out own “Newsletter” post type and get to work.

Wordpress Newsletter Cusotm Post Type

Step 1:  Register the Custom Post Type

When creating a new custom post type, the first thing you need to do is register it with your WordPress install.  This can happen at the theme or plugin level.  In my trials with custom post types, I’ve always done it at the plugin level (mainly because I’m a developer, not a designer).

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//Set up custom post type variables.
$labels = array(
   'name' => _x('Newsletters', 'post type general name'),
   'singular_name' => _x('Newsletter', 'post type singular name'),
   'add_new' => _x('Add New', 'Newsletter'),
   'add_new_item' => __('Add New Newsletter'),
   'edit_item' => __('Edit Newsletter'),
   'new_item' => __('New Newsletter'),
   'view_item' => __('View Newsletter'),
   'search_items' => __('Search Newsletters'),
   'not_found' =>  __('Nothing found'),
   'not_found_in_trash' => __('Nothing found in Trash'),
   'parent_item_colon' => ''
);
 
$args = array(
   'labels' => $labels,
   'public' => true,
   publicly_queryable' => true,
   'show_ui' => true,
   'query_var' => true,
   'menu_icon' => get_stylesheet_directory_uri() . '/images/newsletter.gif',
   'rewrite' => true,
   'capability_type' => 'post',
   'hierarchical' => false,
   'menu_position' => 20,
   'supports' => array('title','editor', 'excerpt')
);
 
//Register the newsletter post type.
register_post_type( 'newsletter' , $args );

Now, lets disect this a bit so you know what’s going on.

  • Labels
    • name – The name of your custom post type.  Usually this is the plural form of it.
    • singular_name – This is the singular form of your plural name.
    • add_new – Normally when you add a post, you click “Add new”.  It’s the same thing for this example.  However, you could make it say “Be more awesome! Add a newsletter!” (if you REALLY wanted to).
    • edit_item – Same as add_new.  You can change how the edit link is displayed.
    • new_item – When you first create your new newletter, this is what it will describe it as.  Once you have a title on it, it will display that instead.
    • For more information on these, I suggest the WordPress Codex.
  • Args
    • labels – General label information for your custom post type.
    • public – Should this be made available to all users?
    • publicly_queryable – Should the public be able to run queries against your post type?
    • show_ui – Do you need a user interface?
    • menu_icon – Path to the icon that is displayed in the admin.
    • rewrite – Should WordPress attempt to make the urls friendly?
    • supports – This bit is pretty important.  This is where you describe what is shown in the admin.  Currently I have “title”, “editor”, and “excerpt”.  You can also extend this with your own stuff later.
    • For more information on these, I suggest the WordPress Codex.
  • register_post_type – This hook is how you register your shiny new custom post type with WordPress 3.0.  First argument is a unique name that you give to your custom post type.  The second argument is the array that was defined above.

Step 2: Custom Categories (Taxonomy) [optional]

One of the nice things about custom post types in WordPress 3 is that you don’t have to use the same categories (taxonomy) as your other posts  and pages.  Registering a new taxonomy for your custom post type is very easy.

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//Create taxonomy for categorizing newsletters
register_taxonomy(
   "Categories",
   array("newsletter"),
   array("hierarchical" => true,
      "label" => "Categories",
      "singular_label" => "Category",
      "rewrite" => true)
);

How this works is fairly straight forward.  The first argument is what you’d like your new post type categories to be called.  In this example, I opted for simplicity and went with “Categories”.  The second argument is the post types that you would like this taxonomy to show up on.  Since we only want it on our new post type, I’ve defined it as such.  The third argument is for options (lables, rewrite on/off, etc).

Step 3:  Your done!

Really, it’s that easy.  If you want to make it really useful, you need to add meta boxes to admin interface so that you can do sweet custom content.  But at it’s bare minimum, this is all you need.

If there is sufficient interest, I can go into deeper detail about making a plugin with a custom post type.  Also, if you need help, drop a comment and I’d be happy to give your problem a shot.

Categories
Other

Wedding & Honeymoon

Just wanted to put a quick post out saying that there won’t be any updates for the next few weeks. My fiancé and I will be getting married on 7/31 and will be leaving for our honeymoon on 8/3.

Wish me luck! When I return, I hope to run a post on making custom post types play nice in WordPress 3.0.

Categories
PHP Programming

PHP Function Of The Day: ob_end_clean()

Sometimes you get in to a situation where you are working in an environment that drops everything into an output buffer before it spits it out the browser. In most languages this is called “output buffering”. The problem with having EVERYTHING buffered is being able to do special stuff like dynamic XML documents.

My solution to this little pickle was to just drop everything from the current output buffer and then kill the process after I’m done with it. To do this, just execute “ob_end_clean()” right before the functions/objects/code you need to execute. What “ob_end_clean()” does is drops all information that is currently stored in the output buffer, and then stops the buffering anything after it.

One “gotch ya” moment I had using this function was that it doesn’t end ALL cases of output buffering. If for some strange reason there is nested buffering going on, you’ll need to call the function as many times as it takes to get to the top of the call stack.

http://us2.php.net/manual/en/function.ob-end-clean.php