How to make WordPress print the date every time

Posted on April 28, 2010 by Vincent — Leave a comment

If you are using the template function the_date or get_the_date while listing posts you might notice that the date doesn’t get printed every time.

This is because the previous day is stored so that it doesn’t print the date stamp more than once.

A simple work around is to simply use the function the_time instead, or by resetting the $previousday variable with a filter.

function mytheme_the_date($date){
global $previousday;

$previousday = null;

return $date;
}
add_filter( 'the_date', 'mytheme_the_date' );

Even though I would recommend the first alternative it is good to know why the date doesn’t appear!

Tagged with: date, php, the_date
Posted in Beginner

WordPress saves Objects and Arrays as serialized strings

Posted on March 24, 2010 by Vincent — Leave a comment

If you often use functions such as update_option, update_post_meta (or any meta-function for that matter) it might be useful to know that the value you pass can be mixed.

When looking the function reference for add_post_meta, it says that the value must be a string. But the value may also be an array, or even an object.

The value is serialized before it is saved, which in short means that it is converted to a string.

Example:

$arr = array("mixed array", "of" => "different values");
add_post_meta(1, "serialize_test", $arr, true);

$meta = get_post_meta(1, "serialize_test", true);

echo "<pre>";
print_r($arr);
echo "\n";
print_r($meta);
echo "</pre>";

Output

Array
(
    [0] => mixed array
    [of] => different values
)

Array
(
    [0] => mixed array
    [of] => different values
)

So it is very useful to know this, and even more useful to know that sometimes even the WordPress Codex can be wrong!

Tagged with: meta data, serialization
Posted in Intermediate

Google Charts?

Posted on March 23, 2010 by Vincent — Leave a comment

Google Charts in WordPress? Hmm, maybe!

Tagged with: google charts
Posted in Misc

Style WordPress images and captions

Posted on March 22, 2010 by Vincent — 2 Comments

When inserting an image into the rich text editor you get the following:

The WordPress logo

When viewing the code in the HTML tab you see that the following Shortcode is created:

[ caption id="attachment_75" align="alignnone" width="150" caption="The WordPress logo" ]<a href="https://wpquicktips.wordpress.com/wp-content/uploads/2010/03/blue-l.png"><img class="size-full wp-image-75" title="WordPress" src="https://wpquicktips.wordpress.com/wp-content/uploads/2010/03/blue-l.png" alt="" width="150" height="150" /></a>[ /caption ]

And the Shortcode creates the following HTML:

<div style="width: 160px;" class="wp-caption alignnone" id="attachment_75"><a href="https://wpquicktips.wordpress.com/wp-content/uploads/2010/03/blue-l.png"><img height="150" width="150" alt="" src="https://wpquicktips.wordpress.com/wp-content/uploads/2010/03/blue-l.png?w=150&amp;h=150" title="WordPress" class="size-full wp-image-75"></a><p class="wp-caption-text">The WordPress logo</p></div>

When developing new themes it really helps to use the existing markup. You could redo the HTML if you wanted by using filters, but why invent the wheel twice?

Tagged with: captions, CSS, html
Posted in Beginner

How to change the allowed HTML tags for WordPress

Posted on March 12, 2010 by Vincent — 26 Comments

WordPress by default filters out potentially harmful and/or invalid HTML. But in some cases you might want some of that invalid HTML!

One of those cases occurred today when we needed to embed a Google Form in a post. To do so, Google provides you with HTML code that contains a iframe, but uh-oh! The iframe element is not allowed by default.

If you look in wp-includes/kses.php you see a variable called $allowedposttags. The array contains all the allowed tags, and their allowed attributes. So you could also change the allowed attributes for the already allowed elements if you so wish.

To include iframe in the list of allowed element I added the following code to my theme’s functions.php:

$allowedposttags["iframe"] = array(
 "src" => array(),
 "height" => array(),
 "width" => array()
);

And something that is always requested is the ability to simply just paste the embed-code provided by YouTube or Vimeo without having it filtered out. To do so simply add this to your functions.php or plugin:

$allowedposttags["object"] = array(
 "height" => array(),
 "width" => array()
);

$allowedposttags["param"] = array(
 "name" => array(),
 "value" => array()
);

$allowedposttags["embed"] = array(
 "src" => array(),
 "type" => array(),
 "allowfullscreen" => array(),
 "allowscriptaccess" => array(),
 "height" => array(),
 "width" => array()
);

But if you want to embed Flash files in a more standard compliant and modern way, check out our Easy Flash Embed plugin instead!

Tagged with: html, iframe, vimeo, youtube
Posted in Intermediate

Never use PHP short tags for WordPress development

Posted on March 5, 2010 by Vincent — 3 Comments

Today while working on a project where we had collaborated with freelance developers I noticed that some pages weren’t looking as they should. A quick glance at the code revealed that the developer was using “short tags” to include the header.

<? get_header ?>

To use short tags, the short_open_tag option must be turned on in php.ini. On most servers short_open_tag is turned on, but alot of servers (like my local server) has it turned off.

If you are developing a theme for a specific server environment, this may be acceptable. But if you are developing a theme or a plugin to be used by a lot of people on a lot of different server environments then short tags can not be used!

Tagged with: php, short tags, short_open_tag
Posted in Best Practices, Misc

Embed Flash files in WordPress

Posted on March 2, 2010 by Vincent — 5 Comments

While developing a site for a client a need emerged for us to be able to embed Flash files in the content.

To do so you could paste some HTML in the content editor and hope for it not to be parsed away. And to keep it the HTML or XHTML valid while doing so, and to support alternative content might be a bit tricky.

I thought that I would fix this problem using the Shortcode API, and also to make a plugin out of it while I was at it.

The result is Easy Flash Embed!

Embed Flash easily and standard compliant with SWFObject using only a [swf] shortcode!

In the text editor simply write something like:

[swf src="http://www.example.com/my-flash-file.swf" width=300 height=100]

You can even add some alternative content by writing something between the brackets:

[swf src="http://www.example.com/my-flash-file.swf" width=300 height=100]You must have Flash to view this file[/swf]

Tagged with: embed, flash, shortcode api, swf, swfobject
Posted in Beginner

Use WordPress functions to include your CSS

Posted on February 21, 2010 by Vincent — Leave a comment

When I’m not developing for WordPress, I try to use a specific folder structure for my project. I have all my .css-files in the /css/-folder, all JavaScript in /js/-folder and so forth.

I tried to keep this up for WordPress, and placing my CSS in the root instead of the theme folder, but this quickly changed. Mainly because it’s easier to manage when you have all your files in one folder (your theme folder). And also because it’s not the way it’s meant to be done.

You can use functions as bloginfo(“stylesheet_url”) to include style.css. The function generates a complete URL, which is great since you should always have a complete URL due to performance issues.

Tagged with: CSS, performance
Posted in Beginner, Best Practices

Use an empty action attribute in forms

Posted on February 17, 2010 by Vincent — Leave a comment

When developing a simple form to use in your WordPress theme or plugin you often want to post to the same page.

To do so, simply leave the action attribute empty in your form.

<form action="" method="post">
<div>
<label>Name</label><br />
<input type="text" name="your_name" />
<input type="submit" value="Send" />
</div>
</form>

Notice that your_name is used, using simply name as the attribute value may cause some trouble. At least it did for me.

Mark Jaquith has written a bit more detailed about the action attribute.

Tagged with: action attribute, forms
Posted in Best Practices, Intermediate

Make use of the body_class function

Posted on February 11, 2010 by Vincent — Leave a comment

The function body_class was introduced in WordPress 2.8 and should be included in every theme.

Include it in your HTML like so:

<body <?php body_class(); ?>

And you will end up with something like this

<body class="page page-id-4 page-parent page-template page-template-default">

It can come quite handy when you want pages to have different color themes for example. Just like the classes in your navigation, the classes can be altered with the body_class filter.

For example, filter the classes so that page-id-4 becomes page-YOUR-SLUG

function my_theme_body_class($classes, $class){
	global $post;
	foreach($classes as &$str){
		if(strpos($str, "page-id-") > -1){
			$str = "page-" . $post->post_name;
		}
	}
	return $classes;
}
add_filter("body_class", "my_theme_body_class", 10, 2);

Hope you find it useful!

Tagged with: body_class, CSS
Posted in Beginner, Best Practices

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