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 http://digwp.com/u/117. 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 – http://digwp.com/u/118 ): <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: http://digwp.com/u/411 111 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', ("http://ajax.googleapis.com/ajax/libs/ 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 = "http://twitter.com/statuses/user_timeline.json?callback=?"; $.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="http://search.twitter.com/ search?q=%23$2">#$2</a>') .replace(/(^|\s)@(\w+)/g,'$1<a href="http://twitter. com/$2">@$2</a>') ) $tweet.append(" &nbsp;<a href='http://twitter.com/" + 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 http://digwp.com/u/228. There are also quite a number of plugins for WordPress that specially deal with Delicious – http://digwp.com/u/229. 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 – http://digwp.com/u/230. 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('http://digwp.com/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. http://delicious.com 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 http://digwp.com/u/140, 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 http://digwp.com/u/141 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('http://digwp.org', 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: http://digwp.com/u/405 . 107 <a href="<?php echo get_permalink( $comment- >comment_post_ID ) . '#comment-' . $comment->comment_ID; ?>">< ?php echo dp_get_author($comment);. http://digwp.com/u/118 ): <ul class="popular-posts"> <?php $popular_posts = $wpdb->get_results("SELECT id,post_title FROM {$wpdb->prex}posts ORDER BY comment_count DESC. 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,