WordPress Consultant and Genesis Developer

Rotating banners in WordPress with jQuery

Important Note:

This post is quite dated as it is from 2009. Everything mentioned below will still work, however, since this post was written there have been several plugins released that are worth considering first. Make sure and check out the list below!

These are the ones I recommend. If these do not fit the bill there are tons to choose from on WordPress.org

Recently I had a project that needed to have a rotating banner on the main page. Most rotating banners out there are connected to feature posts or articles. WooThemes and some of Matt Brett’s projects often use this method.

This wasn’t going to cut it for me. I needed to have rotating banners that were not associated to any posts, could link off site, be updated/maintained by the client, and preferably not use any custom field voodoo. The last thing I wanted to do was use a post category since it would be major over kill.

So I came up with a solution that fit all my requirements above and works great. Figured I would share what I did in case anyone else needs a similar solution.

The rotating banners were accomplished using:

Let’s get started here.

Step 1: setup a link category

When you’re logged into the WP admin panel, click on Links on the left (under Media, above Pages). The Links section will expand and now we need to create a Link Category.

add_link_cat

Add your Banner category

After you have added your Banner category (or whatever you decide to name it) you want to find the ID for that category. There are 2 ways you can do this. First, place you cursor over the category and look in browser status bar.

find_cat

The second option is to use Sivel’s Simply Show IDs plugin which will tell you the ID. Either way, just make sure you note what the ID is for your category since we will need it later.

Step 2: add some banners

Now we will add some links to the category. Click Add New under Links.

add_link

The name and description is for your reference and will not be shown or used. Make sure you place the link in the category you created. Lastly you will need to put the location of the image in the Image Address field. The easiest way is to upload your banners using the WordPress Media manager. If you go that route your image location will be something similar to http://yoursite.com/wp-contents/uploads/11/09/banner.jpg.

Step 4: downloading  and moving jQuery Carousel

Now that we have the banner category created and some links/images in the category we need to get things setup behind the scenes.

First, download jQuery Carousel.

Secondly, unzip the files. You will see a bunch of files, most of which we won’t need.

Open up your theme folder (/wp-contents/themes/yourtheme/) and create a folder inside called js.

Now we need to move jquery.jcarousel.pack.js or jquery.jcarousel.js (look in the /libs/) to this folder. The path should be similar to /wp-contents/themes/yourtheme/js/jquery.jcarousel.pack.js

Note: It is up to you which version of jCarousel you use. I prefer the packed version since it is smaller and we will not need to do any editing.

After the jCarousel javascript file has been moved we need to move over the CSS. Open jquery.jcarousel.css, copy the contents, and paste it into your theme’s style.css.

So to recap, you should have:
/wp-contents/themes/yourtheme/js/jquery.jcarousel.pack.js
/wp-contents/themes/yourtheme/style.css (should contain the CSS from jquery.jcarousel.css)

Step 5: setting up jCarousel and jQuery

Once you have added the necessary jCarousel CSS to your theme’s style.css you will need to edit it to meet the dimensions of your banner.

/* @group jcarousel */

.jcarousel-banners {
 border: 1px solid #cfcfcf;
 margin:0 0 30px 0;
}

.jcarousel-container {
 position: relative;
}

.jcarousel-clip {
 z-index: 2;
 padding: 0;
 margin: 0;
 overflow: hidden;
 position: relative;
}

.jcarousel-list {
 z-index: 1;
 overflow: hidden;
 position: relative;
 top: 0;
 left: 0;
 margin: 0;
 padding: 0;
}

.jcarousel-list li,
.jcarousel-item {
 float: left;
 list-style: none;
 /* We set the width/height explicitly. No width/height causes infinite loops. */
 width: 578px;
 height: 130px;
}

/**
 * The buttons are added dynamically by jCarousel before
* the</pre>
<ul>
<ul>list (inside the</ul>
</ul>
<div>described above) and
 * have the classnames "jcarousel-next" and "jcarousel-prev".
 */
.jcarousel-next {
 display: none;
}
.jcarousel-prev {
 display: none;
}

.jcarousel-banners .jcarousel-list li,
.jcarousel-banners .jcarousel-item {
 position: relative;
 float: left;
 list-style: none;
 width: 578px;
 height: 130px;
}

.jcarousel-banners .jcarousel-container-horizontal {
 width: 578px;
}

.jcarousel-banners .jcarousel-clip-horizontal {
 width: 578px;
 height: 130px;
}

.jcarousel-banners .jcarousel-item {
 width: 578px;
 height: 130px;
}

Above is what the CSS looks like for my website. The size of the banners is 578x130px. Change this to the size of your banners. You might need to do some further tweaking later.

Now the CSS is done and jCarousel is in place we need to tell WordPress to use jQuery and jCarousel when it loads a page.

Open up functions.php inside your theme directory. You may have to create it if your theme does not have one. Now add this:

if (!is_admin()) {
wp_enqueue_script('jquery');
wp_enqueue_script('jcarousel','/wp-content/themes/yourtheme/js/jquery.jcarousel.js',false,false);
}

WordPress includes many scripts out of the box, one of them being jQuery, so there is no need for us to download it. The code snippet tells WordPress – as long as we are not in the admin panel – to load jQuery and the jCarousel script.

Step 6: finishing things up on the front end

Your banners have been created, the files have been moved, and WordPress now knows to use jQuery and jCarousel when a page loads – almost done!

The last thing we need to do is add the code to grab the banners and make them work.

Open up  index.php or home.php (the location you want to place your banners)  in your theme directory and use this snippet:

</pre>
<div id="banners">
<ul>
<ul><!--?php wp_list_bookmarks( 'categorize=0&category=49<&title_li=&before=
	<li-->&after=</ul>
</ul>
<ul>&show_images=1&show_description=0' ); ?></ul>
</div>
<pre>

This snippet will grab links you created earlier and only show the images. Make sure you change category=49 to your category ID.

Lastly, open header.php in your theme directory. Place the code snippet below in between the <head> </head> tags – usually right after you see wp_head();

jQuery(document).ready(function($) {
$('#banners').jcarousel({
scroll: 1,
auto: 4,
wrap: 'last',
animation: 'slow',
buttonNextHTML: null,
buttonPrevHTML: null
});
});

The jQuery that comes with WordPress runs in non conflict mode, which is why do not use the typical document ready call. jCarousel is very configurable, so I suggest you check out all the different options and make sure your settings are set for the functionality you desire.

Step 7: Profit.

That’s it! If you followed all the steps right you should have a rotating banner on your site.

I found this to be a better solution that any of the plugins I found. We didn’t have to do anything crazy, use posts, or write any plugins. Normally I would provide a demo of this in action but I have a feeling the client I did this for would rather not be mentioned.

If you have an questions or problems, feel free to leave a comment.

If you do expereince problems, a few things to double check/tweak:

  • view your source to make sure WP is calling jQuery and jCarousel
  • check to make sure you have the correct category ID
  • modify the CSS if things don’t render correctly

WordCamp NYC 2009

Picture 1I’m throwing around the idea of possibly making a trip up to NYC for WordCamp in a few weeks.

The sessions are are lined up, there are a ton of great speakers, and many of the characters from #wordpress will be in attendance (*cough* sivel, ansi, jdingman, etc).

Not worried about airfare (Go Southwest! ha) or registration, however I am looking for help on lodging.

There is a hotel within walking distance that has a 15% discount, bringing it down to ~ $210/night. I wanted to see if anyone who was thinking about attending would want to maybe slplit a room.

Alternately, anyone have any other recommendations for places to stay? I’d prefer to not shell out $210 a night by myself unless I must. After all in Texas $210 a night would damn near get you a suite! Stupid inflation. ;)

WordPress parent and sub category IDs

The current project I am working left me needing to access the category ID (parent) and sub category ID for the sidebar.php

I have several sections in the sidebar for posts using is_single() that get the most popular posts, recent posts, etc. The problem using the code below – which works if you don’t deal with sub categories – is it only gets the parent category ID.

 $categories = get_the_category();
 $this_cat_ID = $categories[0]->cat_ID;
 $this_cat_name = $categories[0]->cat_name;
 $this_cat_url = get_category_link($this_cat_ID);

For example:
I have News category that has an ID of 6, a Press Release sub category with the ID of 7, and a TV Coverage sub category with the ID of 8.
The sidebar.php contains a block that displays the most recent posts.
If I am viewing a press release post (single.php) I want to see the the only latest Press Release posts. Using $this_cat_ID, which is the parent category ID, it is going to show all the posts in the News including not only Press Release but also TV Coverage.

It’s easy to get the parent category id as I showed above, and while it isn’t difficult to get the sub category ID (or IDs if you have more than one), most examples I found on the WP.org forums didn’t do what I needed. You need to add a few lines to get the sub cat.

$categories = get_the_category();
 $this_cat_ID = $categories[0]->cat_ID;
 $this_cat_name = $categories[0]->cat_name;
 $this_cat_url = get_category_link($this_cat_ID);
 // get the sub category if we have them
 foreach ($categories as $cat) {
    $parent = $cat->category_parent;
    if ($parent != 0 ){
       $sub_cat_ID = $cat->cat_ID;
       $sub_cat_name = $cat->cat_name;
       $sub_cat_url = get_category_link($sub_cat_ID);
    }
 }

With this code you still have access to the parent category ID but also gain the sub category ID.

All that is left is to just write a quick function that checks to see if there is a sub category, something that contains:

if (!$sub_cat_ID) {
   echo $this_cat_ID;
} else {
   echo $sub_cat_ID;
}

Problem solved! Now viewing a post filed under News will show the most recent News posts, a post filed under Press Coverage will show the most recent Press Coverage posts, and so on.

FYI – this method only works if you are going to have a post in one sub category at a time, otherwise you will have to modify things so the sub category info gets stuck in an array.

WordPress 2.8.5 released

WordPress 2.8.5 has been released and is up for download. Nothing exciting to see as it just addresses the exploit that was published this morning plus a few minor things. From the WordPress.org post:

  • A fix for the Trackback Denial-of-Service attack that is currently being seen.
  • Removal of areas within the code where php code in variables was evaluated.
  • Switched the file upload functionality to be whitelisted for all users including Admins.
  • Retiring of the two importers of Tag data from old plugins.

So get your installs up to date by downloading or upgrade in the admin panel!

WordPress trackback exploit found

Around 9am (CST) this morning we were alerted via the wp-hackers mailing list that there is an exploit out that affects the latest version of WordPress, v 2.8.4.

If you want to read more about all the technical stuff you can find the original blog post detailing the exploit here.

I wouldn’t say this is critical since your data is not at risk but anytime someone can put heat on your server it is not good.

No word yet if a patch is going to be released in the form of WordPress 2.8.5. There are a few fixes out already however.

There is a chunk of code you can paste into your theme’s functions.php file.

function ft_stop_trackback_dos_attacks(){
	global $pagenow;
	if ( 'wp-trackback.php' == $pagenow ){
		// DoS attack fix.
		if ( isset($_POST['charset']) ){
			$charset = $_POST['charset'];
			if ( strlen($charset) &amp;gt; 50 ) {  die; }
		}
	}
}
add_action('init','ft_stop_trackback_dos_attacks');

There is also already a fix on trac.

Changing category slug in WPMU

So apparently you can’t change category slugs in WordPress MU. At least not without using phpmyadmin.

If you run into this problem and you don’t have access to phpmyadmin (or don’t want to give users access to it) the Edit Category Slug plugin is your answer. Works flawlessly in WPMU 2.8.4a.

WordPress 2.9 Features

WordPress 2.9 is right around the corner. The fearless and brave have already upgraded to 2.9-rare. I think I’ll wait for the beta to come out before I upgrade, which should be in a week or two.

Anyways, Doug Campbell is one of these people who has to live on the bleeding edge I guess. Actually I have no idea – but he did upgrade his blog to 2.9-rare.

He’s posted a quick article about 2.9 and tacked on a very handy feature list. Probably nothing new if you keep up with WordPress, but a good break down never-the-less.

To summarize what’s new in 2.9:

  • Post thumbnails
  • “trash” status.
  • Image editing (resize, crop, flip)
  • widgets outside the sidebar
  • custom post types
  • better media embeds (think viper’s video quicktags)
  • register_theme_directory() function

You can read a few more details in his write up. WordPress 2.9 is expected to be beta by end of October and hopefully released a month after that.