If you’re working with a complicated site then you may find that importing files and posts into WordPress is a bit of a black art – there are lots of places where things might go wrong. If the upload_url_path value for your site has been manually changed, then this might cause problems with WP export files.

Q: why would you change upload_url_path?

A: changing upload_url_path lets WordPress serve images etc. from a subdomain or different domain, which should improve site performance if you have an image-heavy site.

This is an example item entry from the WordPress eXtended RSS export file (this is a simplified entry, with most of the post data (comment status, stickiness, time, post ID etc. removed for clarity).

<item>
	<title>Triplets</title>
	<link>https://iso200.com/photo-blog/signs/neon-triplets/attachment/dsc_6318/</link>
	<pubDate>Fri, 15 May 2009 20:20:12 +0000</pubDate>
	<dc:creator><![CDATA[dlf]]></dc:creator>
	<guid isPermaLink="false">http://iso200.com/simple/wp-content/uploads/2009/05/dsc_63181.jpg</guid>
	<description></description>
	<content:encoded><![CDATA[neon, sign, Rue de la Paix, Paris, France]]></content:encoded>
	<excerpt:encoded><![CDATA[Rue de la Paix, Paris, France]]></excerpt:encoded>
	<wp:post_id>6</wp:post_id>
	<wp:post_date><![CDATA[2009-05-15 15:20:12]]></wp:post_date>
	<wp:post_date_gmt><![CDATA[2009-05-15 20:20:12]]></wp:post_date_gmt>
	<wp:comment_status><![CDATA[open]]></wp:comment_status>
	<wp:attachment_url><![CDATA[//content.iso200.com/2009/05/dsc_63181.jpg]]></wp:attachment_url>
	<wp:postmeta>
		<wp:meta_key><![CDATA[_wp_attached_file]]></wp:meta_key>
		<wp:meta_value><![CDATA[2009/05/dsc_63181.jpg]]></wp:meta_value>
	</wp:postmeta>
</item>

The problem is with this line:

<wp:attachment_url><![CDATA[//content.iso200.com/2009/05/dsc_63181.jpg]]>

The attachment url line doesn’t contain a protocol – either http or https – which is why my media import failed. A protocol isn’t needed when you change the upload_url_path value – but it is needed when WP is importing media.

Solutions:

1. Post-export: grep the file – add a transport protocol to the url – i.e. http: or https: Don’t forget to add the : after the protocol – the wp:attachment_url line should now look like this:

<wp:attachment_url><![CDATA[https://

2. Pre-export: check your media library settings and make sure a protocol is included:

NB: you only see these options in your Media Settings page if you have changed the value of upload_url_path.

If you have folders full of intermediate thumbnail sizes that you don’t want, you can easily select and delete all the thumbnails WordPress has generated using the right tools. This is particularly useful if you change thumbnail sizes and want to get rid of old images.

If you have a Mac, use ‘Find Any File‘ and use a regex pattern to search for images: -(\d{2,4})x(\d{2,4})\.(jpg|jpeg|png|gif)

The regex will select file names that end with a dash followed by thumbnail width by thumnbmail height and the usual image file name extensions. This is the standard WP thumbnail naming format.

‘Find Any File’ will give you a window of images and you can manage/delete as you want.

If you type an incorrect regex (search) string in, the app will helpfully flag the error:

If you have repeatedly imported a test file into a development server, this may leave you with a number of additional duplicate full-size images in your uploads folder – the regex above will not remove these though.

This string has found a lot of duplicates for me – but not all – but be aware that it may select images that you don’t want, depending on their naming format: (\d)-(\d)\.(jpg|jpeg|png|gif)

TIP:

When you import a test file of WP posts (etc.) into a development server create a new Uploads folder each time you do a test import. This avoids the problem of having duplicate original files.

When is an excerpt not an excerpt?

If you call get_the_excerpt() WordPress returns a string that looks like an excerpt – but it might not be. If your post doesn’t have a handcrafted excerpt, WordPress returns an automatically generated word-counted trimmed-down version of the full post content (see codex).

TL/DR: WordPress returns a string for get_the_excerpt() even when has_excerpt() is FALSE.

I’d used this bit of code to automatically add a ‘read more’ link at the end of every excerpt on a search page.

function ds_excerpt_read_more( $output ) {
 
	$read_more_link = ' (<a class="more-link" href="' . get_permalink() . '">Read more</a>)';
 
	if ( has_excerpt() && ! is_attachment() & is_search() ) {
 
		$output .= " " . $read_more_link;
 
	}
	return $output;
}
add_filter( 'get_the_excerpt', 'ds_excerpt_read_more'  );

Problem was, it wasn’t working everywhere – some posts didn’t have the modified excerpt.

has_excerpt() was the problem – it only returns TRUE if there is a manual excerpt.

So this works better:

function ds_excerpt_read_more( $output ) {
 
	$read_more_link = ' (<a class="more-link" href="' . get_permalink() . '">Read more</a>)';
 
	if ( has_excerpt() && ! is_attachment() & is_search() ) {
 
		$output .= " " . $read_more_link;
 
	} elseif (is_search() &&  ! has_excerpt() )  {
 
		$excerpt_length = apply_filters('excerpt_length', 55);
		$output = wp_trim_words( $output, $excerpt_length, '' );
		$output .= " " . $read_more_link;
 
	}
	return $output;
}
add_filter( 'get_the_excerpt', 'ds_excerpt_read_more'  );

but this is best:

function ds_excerpt_read_more( $output ) {
 
	if (  is_search() && ! is_attachment() ) {
 
		$read_more_link = ' (<a class="more-link" href="' . get_permalink() . '">Read more</a>)';
 
		if ( ! has_excerpt() ) {
 
			$excerpt_length = apply_filters('excerpt_length', 55);
			$output = wp_trim_words( $output, $excerpt_length, '' );
 
			/* Finds the last full stop in the excerpt, removes everything after it. */
			if ( ( $pos = mb_strrpos( $output, '.' ) ) !== false ) {
				$output = substr( $output, 0, $pos + 2 );
			}
		}
 
		/* Appends a 'read more' link at the end of the excerpt - if it's a search */
		$output .= " " . $read_more_link;
 
	}
	return $output;
}
add_filter( 'get_the_excerpt', 'ds_excerpt_read_more'  );

You have to do two things to add a new page template to WordPress.

1. Add a file with the correct name

WordPress uses a template hierarchy – you need to give your template the right name. Either page-ID.php – where ID is the post ID of the page you are targeting, or page-SLUG.php – where SLUG is either the slug of the page you are targeting or an understandable name you can assign through the page interface to pages.

2. Add a ‘Template Name’ declaration at the start of your template file

For WordPress to pick your template up, you need to start each page template file with a Template Name string followed by a unique name for the template:

/*
Template Name: Offer page template
*/

You may not like how WordPress’ Categories widget lists categories – particularly if you want to modify the list that’s displayed and hide some categories or have a custom order of categories (rather than alphabetical or by number of posts).

So what’s the easiest way to customise the display of the Categories widget??

You don’t.

Create a new *menu*, add the categories that you want in the order you want them, and add your new menu to the widget area.

So you can go from this:

to this:

This strange thing happened to me earlier today – added a custom post type earlier this week, published an article this afternoon – but then I couldn’t view the published version – WordPress said it couldn’t be found (404 error).

Solution:

Go to your dashboard, and then to settings/permalinks.

Scroll to the bottom and click “Save Changes”. This will force WordPress to update permalink settings and your posts in your custom post type should now work.

I’ve really started to get into using taxonomies in WordPress. One of the early problems I had though was trying to get them to work – so here’s a few things I’ve learned about WordPress taxonomies.

Don’t define taxonomies in functions.php

This is the classic mistake users (and some developers) make. They register (i.e. define) taxonomies in a theme file, change the theme… and wonder where their taxonomies went! (Hint: they’re still there in your database – but if they’re not registered they can’t be accessed.) The solution to this is simple: use a functionality plugin. Then it doesn’t matter which theme you use: as long as the plugin is active, any theme can access your taxonomy data.

Managing taxonomies

WordPress doesn’t have the most robust set of tools for managing taxonomies – you can’t add them via the interface for example, and there are no built in tools for moving things between tags/categories/taxonomies. There are a couple of plugins that I’ve found very helpful:

Term Management Tools

Want to move terms between tags or categories and taxonomies? Want to rename/combine tags? Term Management Tools does that.

TC Custom Taxonomy Filter

You know those helpful dropdown menus you can use to filter posts by category etc.? TC Custom Taxonomy Filter lets you do that for every taxonomy you define. Very useful.

Making taxonomies appear – aka ‘why doesn’t it work’?

So you’ve defined your taxonomy, you’ve added new items/tags, you click on ‘View’ and you get… a 404 page. Go to Settings: Permalinks and select ‘Save Changes’. (NB: you don’t have to make any changes…!) That will update the rewrite rules and your taxonomy should work… assuming of course that you’ve got posts in that taxonomy.

A taxonomy is just a… category

Don’t believe me? Go to a taxonomy template. Add this:

var_dump($wp_query->query_vars);

Categories, tags, taxonomies… all the same thing.

If you were modifying the admin bar in WordPress 3.x you used to call this:

// Add a link to the dashboard in the [pre-existing] site-name node
$wp_admin_bar->add_menu( array(
	'parent' => 'site-name',
	'id'     => 'dashboard',
	'title'  => 'Dashboard',
	'href'   => admin_url(),
) );

to add a new item to your admin toolbar. Now you just replace add_menu with add_node – they have exactly the same effect – and exactly the same syntax – just a slightly different semantic effect on the reader.