Flickr provides a neat little snippet of javaScript to supply various image galleries direct to your site – a so-named Flickr badge.

So if your gallery is on Flickr – rather in your WordPress, which has its own gallery shortcode – a shortcode in the blog post content can be used to embed a gallery of thumbnail images, which is also a good way to demonstrate the various usages of WordPress shortcodes.

The HTML for a flickr badge looks something like this:-

<div class="flickr_badge"><script type="text/javascript" src="http://www.flickr.com/badge_code_v2.gne?count=5&display=latest&size=m&layout=h&source=all_tag&tag=fish"></script></div>

And the parameters work like this:-

count integer 1-10. Default is 10.

display string ‘latest’ or ‘random’ Default is latest.

layout string h, v, x - Photos are listed horizontally, vertically, or no style. Default is horizontal.

source string user, user_tag, user_set, group, group_tag, all, all_tag

Source implies which ‘account’ the photos come from:- a specified user, a user set, a group, or all users, then filtered by tag if required. Further parameters may then be required, user(ID string) tag (string), group (integer), and set (integer, the url …/sets/1234567/).

size string s, t, m s stands for square (cropped, not small…), t for thumbnail, and m for medium. t = thumbnail is the default.

(idgettr is very useful for figuring out user IDs and the IDs for photosets, groups etc.)

WordPress Shortcodes

A shortcode has a “handler function” – which is integrated into the code by calling the function add_shortcode(). The purpose here is to supply the various parameters for our Flickr badge as parameters of the function – the query string for the Flickr call is then constructed and the javascript code output to the page.

In functions.php

function flickr_badge_shortcode($atts){

//Here's our defaults
$query_atts = shortcode_atts(array('count' => '6', 'display' => 'latest', 'source' => 'user', 'size' => 't', 'user' => '', 'layout' => 'x', 'tag' => '', 'group' => '', 'set' => ''), $atts); 

 	return sprintf('<div class="flickr_badge"><script src="http://www.flickr.com/badge_code_v2.gne?%s" type="text/javascript"></script></div>
', http_build_query($query_atts));
}

add_shortcode('flickrbadge', 'flickr_badge_shortcode');

Provided you have PHP5 on the server, http_build_query() is the quick and easy way of building a query string from an array – and it’s urlencoded….

Note that the empty parameters group, set etc. are required in the defaults – otherwise nothing gets passed to the constructed url via shortcode_atts().

So now, in a post content you can apply the shortcode tag:

[flickrbadge count="4" layout="h" display="latest" size="t" source="all_tag" tag="fish"]

And you should get a nice gallery of Flickr images for users to check out – once you’ve added some CSS to style the images (note the possible uses of the layout parameter here).

This example was of the selfclosing shortcode tag – but you can elaborate a bit, to inject more content into the shortcode function. The simplest example would be to give the gallery a custom title.

Again in functions.php

function flickr_badge_shortcode($atts, $content=NULL){

//Here's our defaults
$query_atts = shortcode_atts(array('count' => '6', 'display' => 'latest', 'source' => 'user', 'size' => 't', 'user' => '', 'layout' => 'x', 'tag' => '', 'group' => '', 'set' => ''), $atts);

return sprintf('<div class="flickr_badge"><h3>%s</h3><script src="http://www.flickr.com/badge_code_v2.gne?%s" type="text/javascript"></script></div>', $content, http_build_query($query_atts));
}

add_shortcode('flickrbadge', 'flickr_badge_shortcode');

And would be called from the post content with opening and closing shortcode tags:

[flickrbadge count="4" layout="h" display="latest" size="t" source="all_tag" tag="fish"]Here’s the latest fish[/flickrbadge]

Caution!
Best to avoid camelCase notation in the attributes – the regex that the content is passed through to locate shortcodes is case-insensitive.
Always remember to use return in the handler function and not echo (in this example sprintf, not printf). It’ll appear on the page – but not in the right place…

WordPress shortcodes are relatively simple in concept, but can be a bit fiddly in practice, keeping track of the default parameters and the use of shortcode_atts() just needs a bit of thinking about sometimes…

It’s really easy to get really mixed up when trying to program with date functions – lots to keep track of, calendars, timezones, daylight saving, weird months that have different numbers of days in them…

Here’s a quick rundown on the main PHP functions involved.

1. checkdate()

bool checkdate ( int $month , int $day , int $year )

Does just what it says, for the Gregorian calendar, and it’s been around since PHP4 – a very quick way to ensure that the programming isn’t coming up with any silly results. Always useful!

2.. date() and gmdate()

From a given UNIX timestamp, date() tells you what time would be in your server timezone and gmdate() tells you what GMT it would be (or UTC, the same thing…). It is important to get the hang of the consequences of this and one way of figuring it out is to bear in mind the date() format character “Z” – the timezone offset in seconds, positive or negative.

No matter what the timezone is set to, these 2 expressions will produce the same result…

<?php
	date_default_timezone_set('America/Montreal');

	echo date("Y/m/d H:i:s",(time()));
	echo gmdate("Y/m/d H:i:s",(time()+ date("Z")));

?>

3. strtotime()

Takes a string and should return a Unix timestamp.

It does say string in “US English date format” – which means that for strtotime (“04/06/2010″) is April 6th, and not the 4th of June. (Probably no need to get into a discussion about the relative logic of the two systems here).

strtotime has a pretty decent understanding of language – so you can do relative times:

strtotime('next Monday');
strtotime('+1 years');
strtotime('first day next month');
strtotime('2010-02 last day');

All return what you’d expect, based on the datetime the function’s run…

4. mktime()

Good for catching “overflows”.

echo date("M-d-Y", mktime(0, 0, 0, 12, 32, 2009)) // => Jan-01-2010
echo date("M-d-Y", mktime(0, 0, 0, 15, 31, 2009)) // => Mar-31-2010

Like strtotime, mktime doesn’t go in unit magnitude order – it’s hours, minutes, seconds, months, days, years…. why? because that’s the decision that was made…

Find a birth day with mktime:-

	$my_birthdate = mktime(0,0,0,5,12,72);
	print date("l", $my_birthdate);
	//gives:   Friday

A Few More Calendar Tricks

Current age

<?php  echo floor(abs(strtotime('Y') - strtotime('02/22/1968'))/31536000);  ?>

Easter date

<?php echo date("M-d-Y", easter_date(2010));   ?>     // Apr-04-2010

Datetime constants
PHP 5.1 and later, via the DateTime class, offers a few shorthand formatting strings.

<?php echo date(DATE_RSS); ?>
//gives something like: Thu, 21 Feb 2010 09:35:44 -0800

The defined strings are here – also good for cookies.

Daylight Saving Problems
One way of cutting out possible problems with daylight saving time differences across timezones is to work in UTC, using expressions like these (and then revert back to a local timezone at the end if necessary).

date_default_timezone_set('UTC');

$date_utc = strtotime($date. " UTC");

Expressivo (Center) is a free WordPress theme – based on Expressivo – a three-column layout, but with the blog post content centered. It’s got the same feature list – a jQuery dropdown pages menu, Cufon embedded fonts for post titles, a custom header image and threaded and paged comments.

Version 1.1 has been tested on Firefox 3, Google Chrome, Internet Explorer 6 & 7 and Opera 9.

Features

• Add your own header image or logo
• jQuery dropdown menu for pages – exclude and configure the item order
• Cufon Embedded fonts
• Custom link and hover colors

Demo: Expressivo (Center) demonstration

Download: Expressivo (Center) WordPress Theme v1.1 – expressivo-center.zip Compatible with WP > version 2.8

This theme is released under the terms of the GPL licence v2.

Our free themes are supplied “as is” – sorry, but we don’t have the resources to offer support for email enquiries or comments about individual installation/customisation.

Mistral is a free WordPress theme – a two-column layout, with a righthand sidebar. Plus a static pages menu, Cufon embedded fonts for widget headings, a replaceable logo area and paged- and threaded- comments.

Version 1.1 has been tested on Firefox 3, Internet Explorer 6 & 7, Google Chrome and Opera 9.

Features

• Replace blog info header with your own logo / design
• Cufon embedded fonts for widget headings
• Customized link and hover colors

Demo: Mistral demonstration

Download: Mistral WordPress Theme v1.1 – mistral.zip Compatible with WP > version 2.9

This theme is released under the terms of the GPL licence, v2.

Our free themes are supplied “as is” – sorry, but we don’t have the resources to offer support for email enquiries or comments about individual installation/customisation.

You need a cron job in your WordPress blog – something run to a schedule, hourly, daily… Instead of fixing up a crontab and using wget or lynx, you can use WordPress’s internal version of the cron job.

This isn’t a true cron job, with a crontab text file sitting on the server – it’s known as a pseudo-cron. Since a script can’t launch itself, it makes use of a visitor, human or maybe robot, launching it by requesting a page. So the job actually runs at the first launch after the scheduled time, not necessarily at the scheduled time to the exact second.

wp_schedule_event()

The most convenient way of using WP-Cron is to wrap it all up in a plugin – so that the scheduling can be done just the once by including it in the plugin activation function.

register_activation_hook(__FILE__, 'my_activation');
add_action('my_hourly_event', 'do_this_hourly');
register_deactivation_hook(__FILE__, 'my_deactivation'); 

function my_activation() {
wp_schedule_event(time(), 'hourly', 'my_hourly_event');
}

function my_deactivation() {
	wp_clear_scheduled_hook('my_hourly_event');
}

function do_this_hourly() {
	// do something here every hour
}

The PHP time() used as an argument indicates “as of now” – so if the plugin is activated at 11:23, an hourly event is going to run at xx:23 from now onwards.

If your code is in for example functions.php and is executed every time the script is executed, you don’t want to keep scheduling the same event. Something like this prevents the problem:-

if (empty(wp_next_scheduled('my_event')))
		wp_schedule_event(time(), 'daily', 'my_event');

WP-Cron Hourly, Recurrence Intervals

Only hourly, daily and twicedaily are available immediately – but there’s a trick to getting more and that’s to tap into the cron_schedules filter and add a key to the schedules array.

add_filter('cron_schedules', 'my_add_weekly');

function my_add_weekly( $schedules ) {
	$schedules['weekly'] = array(
		'interval' => 604800, //that's how many seconds in a week, for the unix timestamp
		'display' => __('Once Weekly')
	);
	return $schedules;
}

With the popularity of jQuery, AJAX, and client-side programming operations in general, there’s more use made of JSON as a format for getting data backwards and forwards.

For example, the Twitter API offers data as JSON – and more manageably than accessing their RSS XML feeds for user timelines etc.

http://twitter.com/status/user_timeline/USERNAME.json?count=10 

The issue is how to make use of JSON-encoded information in the WordPress environment – much of what is available is only recently available, so some care has to be taken about how it’s used.

1. Native PHP functions

json_encode() and json_decode() make life very simple – but these functions are only available in PHP >= 5.2.0 and WordPress is still designed to run on significantly older versions of PHP than this. Alternatives would have to be supplied if you were thinking about releasing a plugin. There are custom-written functions to reproduce these in PHP4, see for example user contributions to json_encode. These are often not 100% perfect, but one may well do all that you require…

2. JSON2

If you’re happy to do the work in jQuery/javaScript, WordPress 2.9 comes with JSON2 bundled, registered and ready to go…

add_action('wp_print_scripts','load_json_parser');

function load_json_parser(){

	if (is_admin()) return; // probably don't want this on admin pages

	wp_enqueue_script('json2');

}

No need any more to play around with eval in the javaScript, but again, this is a WordPress >= 2.9 thing….

3. Borrowing the Text Editor

Lastly, there is one more, slightly unofficial, dodge that can be used. WordPress makes use of TinyMCE as its rich text editor and this comes with the its own JSON parser. Results may not be completely predictable.

require_once(ABSPATH."/wp-includes/js/tinymce/plugins/spellchecker/classes/utils/JSON.php");

$jsObj = new Moxiecode_JSON();

// encodes the supplied array to JSON format
$json = $jsObj->encode(array("key1"=>"value1","key2"=>"value2"));

//decodes supplied JSON to a PHP array
$json_array = $jsObj->decode($json);

People have predicted their death for a long time, but pingbacks/trackbacks (and displaying them) are still firmly with us – there is a certain vanity involved…

They do give an indication of related content, other sites in your niche (and just how many automated spam sites there are out there ) etc. At the same time, they break up the flow of user comments and even with threaded comments can make it difficult for visitors to follow the discussion.

So it’s reasonable to separate out pingbacks and perhaps not include their digest content, just the title and a link. The method has changed for WordPress 2.7 upwards, with the arrival of threaded comments and their integration into the core code.

The frist step is to adjust the call to the comments template in single.php or where ever you’re hoping to display the comments… Replace:

<?php comments_template(); ?>

with

<?php comments_template('', true); ?>

The “true” flag gives access to an array $comments_by_type – as the name might even suggest, a record of the numbers of each type of comment for that post.

Your theme will (should) have something like this code in it – most likely in comments.php but possibly as a separate comments template function in functions.php or elsewhere – the important thing is to locate comments_number() and wp_list_comments()

<h3 id="comments"><?php comments_number('No Responses', 'One Response', '% Responses' );?> to &#8220;<?php the_title(); ?>&#8221;</h3>

<ol class="commentlist">
<?php wp_list_comments(); ?>
</ol>

Replace it with this:

<?php if ( !empty($comments_by_type['comment']) ) : ?>

<h3 id="comments"><?php comments_number('No Responses', 'One Response', '% Responses' );?> to &#8220;<?php the_title(); ?>&#8221;</h3>

<ol class="commentlist">
<?php wp_list_comments('type=comment'); ?>
</ol>

<?php endif; ?>

<?php if ( ! empty($comments_by_type['pings']) ) : ?>

<h3 id="pings">Trackbacks/Pingbacks</h3>
<ol class="commentlist">
<?php wp_list_comments('type=pings'); ?>
</ol>

<?php endif; ?>

We have 2 lists now, created by wp_list_comments

The other (optional) issue is to recalculate the headline figure of comments – which is still showing the total of user comments + pings. This is done with the use of the get_comments_number filter. Add, in functions.php

<?php

add_filter('get_comments_number', 'comment_count', 0);
function comment_count( $count ) {
if ( ! is_admin() ) {
global $id;
$comments_by_type = &separate_comments(get_comments('status=approve&post_id=' . $id));
return count($comments_by_type['comment']);
} else {
return $count;
}
}
?>

And that should be that – next step would be to restyle the two lists, with a customized callback function for wp_list_comments() – but that will have to be for another post…

Expressivo is a free WordPress theme, three-column with two righthand sidebars – going to a single sidebar on single posts and pages. With Cufon embedded fonts for post titles, threaded and paged comments – you can also replace the header completely with your own image.

Version 1.1 has been tested on Firefox 3, Internet Explorer 6 & 7, Google Chrome, Opera 9.

Features

• Custom link and hover colors
• jQuery dropdown menu for static pages – exclude pages and configure item order
• Add your own header image / logo
• Embedded fonts
• Translation ready

Demo: Expressivo demo

Download: Expressivo WordPress Theme v1.1 – expressivo.zip Compatible with WP > version2.8

This theme is released under the terms of the GPL licence.

Our free themes are supplied “as is” – sorry, but we don’t have the resources to offer support for email enquiries or comments about individual installation/customisation. You’re free to use and modify them as you wish, but we would ask you to retain the credit link in the footer.

You want a jQuery slideshow for your WordPress blog? - on the front page, or maybe in the sidebar? No real problem, all the javascript is taken of with the help of a jQuery plugin, all we have to do is figure out how to get the post data.

And to keep things really simple, this is going to use the thumbnail functions in WP 2.9 – no need to mess around with custom fields any more.

Firstly, you do have to explicitly declare the new thumbnail system in functions.php – and best to wrap it up in an “if function exists” to avoid problems for older WP installs.

if (function_exists('add_theme_support')) {
add_theme_support( 'post-thumbnails' );
add_image_size('slideshow-image', 300, 160); // for front page slideshow
}

The smart move is to define a “Featured” category – any post in that category will be available for the slideshow, and that’s the selection taken care of. Create a category – call it featured, or anything, but make a note of the cat_ID – mouseover a category on the admin categories page and it’ll be in the url, something like:

http://testblog.com/wp-admin/categories.php?action=edit&cat_ID=3

The ordering will be by date, newest first. (Don’t forget you can tweak the timestamp of a post if you really want to just to get the order exactly as you want it).

So create a couple of posts in this category and add some thumbnails to them – since our slideshow is going to be 300px by 160px, make sure they’re bigger than that. Then, in home.php, or index.php, where ever you want the slideshow to appear, add:

<?php

$featured_category_id = 3;
$number_of_posts = 4;

$args = array('showposts'=>$number_of_posts, 'cat'=>$featured_category_id);

$slideshow_query = new WP_Query($args);

?>
<div id="slideshow">
<?php
// let's keep a record of the post IDs as we go, in case we want to omit these from other post loops/lists on the same page
$duplicates = array();

while ($slideshow_query->have_posts()) : $slideshow_query->the_post();

//add the ID to the duplicates array for future reference
$duplicates[] = $id;

//test to see whether there's a thumbnail associated with the post
if (has_post_thumbnail()) {
?>
<div class="post-thumbnail">
<a href="<?php the_permalink(); ?>">
<?php	the_post_thumbnail('slideshow-image'); ?>
</a>
</div>
<?php	}
endwhile;
?>
</div>  <!-- end of #slideshow -->

Next, some javascript. We can use the excellent jQuery Cycle Plugin – as the package stands currently, we’ll use jquery.cycle.all.min.js – which allows all the possible transition effects etc. – in practice, you may well want to use the lighter versions…

* For a standard production site, always use min = minified, rather than pack = packed – pack may be a smaller filesize, but it doesn’t run quicker….

We need a very quick script to configure and activate the plugin – so create a new file, slideshow-activate.js

jQuery(document).ready(function($){
$('#slideshow').cycle({
fx: 'fade' // choose your transition type, ex: fade, scrollUp, shuffle, etc...
});
});

Later, there are lots of options here, transition speed, pausing etc. – consult the plugin pages for ideas.

We need to get our scripts on the WordPress page, and indicate that they depend on jQuery being loaded – making use of the WordPress functions wp_register_script and wp_enqueue_script – so in functions.php

add_action('wp', 'js_head_load');

function js_head_load(){

if(is_admin()) return;  //so that we're not loading unecessary scripts in the admin

wp_register_script('cycle', get_bloginfo('template_directory')  . '/scripts/jquery.cycle.all.min.js', array('jquery'), '1.0');

wp_enqueue_script('slideshow-activate',  get_bloginfo('template_directory')  . '/scripts/slideshow-activate.js', array('jquery', 'cycle'), '1.0');

}

And then, don’t forget to put the 2 files into /scripts in your theme folder…

That should give you a working slideshow – ready to be styled with some CSS. Note that the way the Cycle plugin works is that it looks to rotate the immediate children of the div being called – here, they’re images, they could be eg. divs – so if you add a wrapper div(s) you may need to adjust slideshow-activate.js.

And if it’s not working, check first that the right scripts (jQuery, Cycle, slideshow-activate) are actually being loaded and in the right order, by looking at the page source – and check you’ve got thumbnails attached to the relevant posts…

You could go on to tidy this up – avoiding the hard-coded category id by having something in the theme options admin to change the id for example. Also, as said earlier, there’s a lot of scope in playing with the plugin parameters to get exactly the slideshow you want…

Lastly – the record of the duplicates we kept – the method for omitting them from subsequent Loops of posts is here: Multiple WordPress query duplicates

We spend enough time on the blog content and then tend to forget about the comments part. Comments are the way to get people involved – build up a blog’s readership etc etc. A few, sensible, comments trickling in will freshen up a page’s content and make it not seem completely dead in the water to passing search engine crawlers…

And the good news, there’s plenty of comment-related plugins available to get the job done.

First up, though, before anything else – make sure your WP theme and wordpress version are capable of handling threaded- (definitely) and paged- (probably) comments.

The Plugins

Added Value for Comments

DoFollow
By default, WordPress slaps a nofollow attribute on any comment author’s web site link displayed – if you’re not sure what nofollow is, more info here. DoFollow removes this attribute from web site links in comments so search engines can follow them – offering an incentive for people to leave a sensible, or otherwise, comment as they pass by. Which is clearly going to attract spammers as well – always use together with comment moderation.

CommentLuv
An elaboration of the first – more incentives to leave a comment by displaying info about the commentator’s site, with links, such as a selection of their latest blog posts, tweets or diggs.

Subscribe to Comments
Enables commentators to sign up for email notification of subsequent comments – so they can keep in the flow of the discussion.
One operating annoyance with this setup – not the fault of the plugin – involves the dicks who comment using an email address they’ve slapped a spam authentication filter on – so that the poor old WP webmaster gets an email demand for authentication for every subsequent comment until they get round to deleting the offender – a little knowledge being a dangerous thing etc.

Displaying Comments

Twittar
Displays, as an alternative to Automattic’s gravatar, the comentator’s Twitter avatar – if existent…

GD Star Rating
Does depend on the context of your blog, as to whether a comments rating system has value – might be overkill for the average blog…

Gravatar Signup
Adds a checkbox to the comment form for users who don’t have a Gravatar, giving the option to then go on and sign up for one. Prevents the march of grey men down blog comments…

Easy Comment Uploads
Allows a commentator to upload images or other files, togehter with adding their comment – with lightbox display for all added images. It’s obviously wise to be conservative about which file-types you let visitors upload – especially for non-image types.

Ajax Comment Preview
Runs the comment text through the WordPress filters to show a preview – can be useful if commentators are likely to be adding code snippets etc.

Not “comments” plugins as such, but… There are lots of ways of displaying and defining “Popular Posts” – simplest is to go for the posts with the most comments, for example:-

Most Commented Widget
Adds a sidebar widget displaying an ordered list of the posts/pages with the most comments – shows where the action is.

Top Commentators Widget
Appeal to their vanity… and gain spammers.

Anti-Spam Comment Plugins

There’s always Akismet, but there’s also:

Bad Behavior
Attempts to filter out bots by analyzing HTTP requests. Does seem to make a significant difference in server load, monthly bandwidth, for well-established blogs.

OpenID
Asks commentators to sign in before commenting, using their OpenID.
(Update: doesn’t seem 100% functional at the time of writing…)

One small warning – quite a lot of the plugins offered in the WordPress plugin repository are broken or obsolete, due to the arrival of threaded and paged comments. They (probably) won’t break the whole install if you run them, but don’t be too surprised if they don’t do what they’re supposed to…