That’s because the file in which is_plugin_active() is defined – wp-admin/includes/plugin.php – is only loaded in the admin, after your plugin is loaded. Thus, you can only call it after ‘admin_init’ has fired: function check_some_other_plugin() { if ( is_plugin_active(‘some-plugin.php’) ) { … } } add_action( ‘admin_init’, ‘check_some_other_plugin’ );
Here’s a way to test the core patch #33300.6 by Andew Ozz, through a test plugin in WP 4.5.2, to try out the text pattern filter. Demo Here’s a strikethrough example using ~ $init[‘wpsetextpattern_inline_patterns’] = ‘{ strong: { start: “*”, end: “*”, format: “bold” }, strong2: { start: “**”, end: “**”, format: “bold” }, em: … Read more
As a rule of thumb, you should use a POST request for most actions, to make sure they are not executed by accident. But it is also a good practice to redirect to a normal page after a POST request, to prevent duplicate execution when the user refreshes the page. So the flow is like … Read more
The reason this doesn’t work is because there is a redirection happening after the save_post action. One way you can acheive want you want is by implementing a quick work around using query vars. Here is a sample class to demonstrate: class My_Awesome_Plugin { public function __construct(){ add_action( ‘save_post’, array( $this, ‘save_post’ ) ); add_action( … Read more
Use wp_register_style and wp_enqueue_style to add the stylesheet. DO NOT simply add a stylesheet link to wp_head. Queuing styles allows other plugins or themes to modify the stylesheet if necessary. Your stylesheet can be a .php file: wp_register_style(‘myStyleSheet’, ‘my-stylesheet.php’); wp_enqueue_style( ‘myStyleSheet’); my-stylesheet.php would look like this: <?php // We’ll be outputting CSS header(‘Content-type: text/css’); include(‘my-plugin-data.php’); … Read more
Remove what you add First, please make sure that everything you add on activation also gets removed on uninstall. I got a short tutorial including example code for you. Test with a small plugin: I really don’t know much about MU, but as far as I can tell, the roles object is global across all … Read more
A small source, perhaps for a plugin to create the solution. At first the php part, there include the javascript for the button inside the Media Manager. Is more usable answer, but the answer of @One Trick Pony was create and the right direction and JS solution. See the result on the image: The resulting … Read more
The easiest way to do this is actually a combination of wp_enqueue_script and the footer actions that Saif and v0idless already referenced. I frequently use jQuery in my themes and plugins, but I put all of the other scripts in the footer as well. The best way to actually queue things up would be this: … Read more
Late answer & edit. Disclaimer: The following is no copy & paste-togo code. Rough Sketch As I never tried misusing the media modal for anything else, here’s a short overview, sketched by breaking out a part from a project I’m currently on. It’s not a ready to go example, but it should bring you close … Read more
AFAIK, there’s no official/standard framework, and there will be as many plugin development styles as there are shades of white in north pole. I’d say WordPress Coding Standards is a blueprint for a good style. You’ll find lots of good examples and excellent coders here in WPSE. A nice starting point: questions/tagged/plugin-development. Highlighting: Objective Best … Read more