Tìm Hiểu về Wordpress - part 13 pdf

107
<a href="<?php echo get_permalink( $comment-
>comment_post_ID ) . '#comment-' . $comment->comment_ID; ?>">< ?php echo
dp_get_author($comment); ?>:</a>
< ?php echo strip_tags(substr(apply_lters('get_
comment_text', $comment->comment_content), 0, $comment_len)); ?>
</li>
< ?php
ob_end_ush();
}
} else {
echo '<li>No Comments</li>';
}
}
function dp_get_author($comment) {
$author = "";
if ( empty($comment->comment_author) )
$author = 'Anonymous';
else
$author = $comment->comment_author;
return $author;
} ?>
To use this function, simply call it from anywhere in your theme:
<?php dp_recent_comments(6); ?>
4.4.3 Displaying Recent Posts
Lets do this again from easiest to hardest.
• Widget - The easiest possible way to do this is through a widgetized sidebar.
108
Just like recent comments, there is a built-in “Recent Posts” widget which will
do the trick. Just drag it into your sidebar zone and save it.
• Function - We don’t have to write a custom function this time, we can just

use the wp_get_archives function, which we already looked at a little. A simple
function like this will display linked titles to recent posts:
<?php wp_get_archives('type=postbypost&limit=5');
• Custom Loop - Finally we could go totally home-brew and just write a custom
loop to display recent posts. This offers by far the most control as we can do
anything inside this loop, including accessing the full content or custom fields.
<?php
query_posts("posts_per_page=10&what_to_show=posts&orderby=date");
if (have_posts()) : while (have_posts()) : the_post();
// output custom stuff here! Post title, content, custom elds
endwhile; else:
// message if nothing found
endif;
wp_reset_query();
?>
4.4.4. Listing Popular Posts
Popularity is more loosely defined than something like “recent.” How do you
define popularity? Page views? Number of comments? Back links? If you want
to accommodate all the above, try the WordPress Popular Posts plugin, which is
available at
This plugin logs relevant data and then makes outputting a list of popular posts as
trivial as using this template tag anywhere in your theme:
Resetting
The query string is set when
any page in WordPress is
loaded. You can override it by
doing you own query_posts,
but then that original query
string is destroyed. You can
restore it with this:

wp_reset_query();
109
<?php if (function_exists('get_mostpopular')) get_mostpopular(); ?>
If you wanted to gauge popularity only based on the number of comments, you
could achieve this with your own database query (thanks to the Bin Blog for the
idea – ):
<ul class="popular-posts">
<?php $popular_posts = $wpdb->get_results("SELECT id,post_title FROM
{$wpdb->prex}posts ORDER BY comment_count DESC LIMIT 0,10");
foreach($popular_posts as $post) {
print "<li><a href='". get_permalink($post->id) ."'>".
$post->post_title."</a></li>\n";
} ?>
</ul>
4.4.5 Listing Recently Modified Posts
You might think we’d have to go database fishing or use a plugin for this. We
certainly could, but the query_posts function supports an orderby parameter which
can get the job done for us easily:
<?php query_posts("posts_per_page=5&what_to_show=posts&orderby=modied");
if (have_posts()) : while (have_posts()) : the_post();
// output custom stuff here! Post title, content, custom elds
endwhile; else:
// message if nothing found
endif;
wp_reset_query(); ?>
Function exists?
Before using a function that
was created via a plugin,
it is best practice to use the
function_exists() function

before calling it. If the
function doesn’t exist (i.e.,
the plugin isn’t installed or is
deactivated), the function won’t
be called. That is far better
than calling a nonexistent
function since PHP will
halt rendering and will likely
destroy your theme.
110
4.4.6 Listing Random Posts
Again the query_posts function has our back, allowing the orderby parameter to
accept “rand" to display a series of random posts:
<?php query_posts("posts_per_page=3&what_to_show=posts&orderby=rand");
if (have_posts()) : while (have_posts()) : the_post();
// output custom stuff here! Post title, content, custom elds
endwhile; else:
// message if nothing found
endif;
wp_reset_query(); ?>
4.4.7 Import and Display Twitter
Integrating your recent tweets from Twitter can be a fun way to communicate
with your web visitors and keep content on your site fresh. Twitter has a robust API
system for getting at and using that data. But Twitter is not an infallible service,
and in fact, slowness and downtime is a pretty common occurrence for them.
Because of this, when using their API to get stuff and display it on your own pages,
it should be done in such a way that won’t affect the loading of the page, and
won’t look awful in the case of API failure.
This Twitter API communication can be done entirely through JavaScript, which is
our preferred and recommended way for a few reasons:

• Connection to the Twitter API happens on the client side and keeps server
load down
• If done right, doesn’t affect page load time
• Data can be processed and appended to the page only upon success
With Ajax
A neat idea with this technique
is to make a page template
that displays just one post and
nothing else. Then use Ajax to
call that URL and display it
(for example, in the sidebar).
We cover (and use) this
technique on the Digging Into
WordPress website, including
a “Get Another!” button:
/>111
So let’s get it done. We are using jQuery in this book
(because it’s awesome) so let’s keep going down
that route.
Step 1: Enqueue jQuery
Put this PHP code into your functions.php file.
This will load the jQuery library onto your page by
inserting a link in the <head> section where you call
the wp_head function.
if(!is_admin()) {
wp_deregister_script('jquery');
wp_register_script('jquery', (" />jquery/1.3.2/jquery.min.js"), false, '1.3.2');
wp_enqueue_script('jquery');
}
Step 2: Load your custom script

You’ll need to load a JavaScript file for this, so if you have one already going for
your site, you can use that, otherwise load in a new one.
<script type="text/javascript" src="<?php bloginfo('template_url'); ?>/js/
twitter.js"></script>
Step 3: The jQuery plugin
Next, we want to create a jQuery plugin:
(function($){
$.fn.lastTwitterMessage = function(username){
In the footer of CSS-Tricks,
a speech bubble is displayed
above Chris showing his
latest tweet. With this jQuery
method, should the Twitter
service be unavailable,
the speech bubble just
doesn’t show.
112
var $base = this;
if(!username || username == "") return this; // username required
var url = " /> $.getJSON( url, { count: 10, screen_name: username },
function(data){
if(data && data.length >= 1){
try{
var item = null;
for(var i = 0; i < data.length; i++){
if(/^@/i.test(data[i].text)) continue;
item = data[i]; break;
}
if(!item) return;
var $tweet = $("<p></p> ").text(item.text);

$tweet.html(
$tweet.html()
.replace(/((ftp|http|https):\/\/(\w+:{0,1}\w*@)?(\S+)
(:[0-9]+)?(\/|\/([\w#!:.?+=&%@!\-\/]))?)/gi,'<a href="$1">$1</a>')
.replace(/(^|\s)#(\w+)/g,'$1<a href=" />search?q=%23$2">#$2</a>')
.replace(/(^|\s)@(\w+)/g,'$1<a href="http://twitter.
com/$2">@$2</a>')
)
$tweet.append(" &nbsp;<a href=' + username +
"'>(&#8734;)</a>&nbsp; ").wrapInner("<span>");
$base.empty().append($tweet).show();
} catch (e) { };
113
};
});
return this; // Don't break the chain
};
})(jQuery);
That plugin, when we call it, does all the heavy lifting of communicating with
Twitter and pulling the latest tweet. It even does fancy stuff like turning URLs into
real links, hash tags into search links, and @replies into profile links.
Step 4: Calling the plugin
You could load in another JavaScript file just for this, or just append this beneath
the code you just added. We need a DOM-ready statement and then create an
element to load the plugin on.
$(function() {
$("<div id='tweet'></div>").hide().appendTo("#footer")
.lastTwitterMessage('chriscoyier');
});
That code is the magic. It waits for the page to be ready to be manipulated (DOM-

ready), creates a new (hidden) element, appends it to the page (into the footer),
and then calls the plugin on it. Should the plugin be successful in its duty, the new
element will show up on the page, if not, it will remain hidden.
4.4.8 Import and Display Delicious
There is, unsurprisingly, a number of ways to get this done. Delicious has APIs we
could wrangle with (JSON or XML). Delicious serves up RSS feeds we could parse
(see the next section). Delicious has JavaScript widgets that we could harness –
114
There are also quite a number of plugins for WordPress that
specially deal with Delicious – />There is one technique that stands out above the rest though, and that is a plugin
which imports data from your Delicious account and creates Posts from it. It’s
called Postalicious – It’s been a few years since it has been
updated but it still works swimmingly with the current version of WordPress.
Postalicious is able to check Delicious every hour and pull in new links. You can set
it to create drafts (recommended) or auto-publish posts. Simply choose a category,
and Postalicious will automatically create the posts, the title, and all of the HTML
formatting!
It should be noted that Delicious actually has some built-in (albeit rather hidden)
functionality right in the web app for communicating with a WordPress blog. It
isn’t very user-friendly and is difficult to customize, so we don’t recommend it.
4.4.9 Import and Display Other Content
An interesting fact about WordPress that you may not know is that it includes a
built-in RSS feed parser. This makes the job of fetching recent content from other
sites for display on your own pretty darn easy. You’ll need to include the feed.php
file that ships with WordPress on any page you want to do feed parsing, but after
that you are free to set up new SimplePie objects and do all the feed parsin’ you
desire! Check it out:
<h2>Recent News from Digging Into WordPress</h2>
<?php // Get RSS Feed(s)
include_once(ABSPATH . WPINC . '/feed.php');

// Get a SimplePie feed object from the specied feed source.
$rss = fetch_feed(' />Wha?
What the heck is Delicious
you ask? Delicious is a very
popular social bookmarking
site. You save links with
annotation to your account
online (so you’ll never lose
them). And because others do
the same, Delicious is able
to know and share what are
the most popular links going
around at any
given moment.

115
// Figure out how many total items there are, but limit it to 5.
$maxitems = $rss->get_item_quantity(5);
// Build an array of all the items, starting with element 0 (rst element).
$rss_items = $rss->get_items(0, $maxitems);
?>
<ul>
<?php if ($maxitems == 0) echo '<li>No items.</li>';
else
// Loop through each feed item and display each item as a hyperlink.
foreach ( $rss_items as $item ) : ?>
<li>
<a href='<?php echo $item->get_permalink(); ?>' title='<?php echo
'Posted '.$item->get_date('j F Y | g:i a'); ?>'>
<?php echo $item->get_title(); ?></a>

</li>
<?php endforeach; ?>
</ul>
SimplePie is a very robust feed parser, so you are in no way bound by the code
above for what you are able to accomplish. For a complete list of functions, check
out the SimplePie wiki at but to get the juices flowing, here
are some examples.
At the “feed level” (outside the feed loop), get the title, description, and
permalink of the feed:
Quick Backstory
WordPress used to use
MagpieRSS to do its feed-
parsing. The project was
discontinued and one of its
competitors SimplePie was
gaining traction in a big way.
WordPress switched over to
SimplePie, and now SimplePie
development has ended.
Someone may pick up
SimplePie and run with it,
but it seems like inclusion into
WordPress is the kiss of death
for any feed parser.
116
• get_title()
• get_description()
• get_author()
At the “item level” (inside the feed loop), get the date, content, and link:
• get_date()

• get_content()
• get_link()
The SimplePie Plugin />SimplePie has a plugin for WordPress as well. It was probably more useful back
when WordPress didn’t ship with SimplePie, but the user-friendliness of it still
makes it a pretty cool plugin. Once installed and activated, you can spit out
external content as easy as calling the plugin function:
<?php
echo SimplePieWP('', array(
'items' => 5,
'cache_duration' => 1800,
'date_format' => 'j M Y, g:i a'
));
?>
Notice that the URL parameter isn’t a feed but rather just a regular website.
SimplePie is cool like that, with automatic feed detection. The plugin uses
“themes” to then output the content it finds. It ships with a number of themes,
which you can select and modify through the admin itself. Anything you can do
with SimplePie you can do with this plugin as well, the big advantage being the
themes and control through the Admin.
Importing Feeds
For an in-depth article
explaining everything you need
to know about importing and
displaying feeds in WordPress,
check out this post from
Perishable Press:
/>