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1. martinstrouhal
   Member
   Posted 10 months ago #

   Hi,
   I'm trying to write my first wordpress plugin.
   Here is my code:
   

   <?php
   /*
   Plugin Name: Hello-World
   Plugin URI: http://yourdomain.com/
   Description: A simple hello world wordpress plugin
   Version: 1.0
   Author: martin
   Author URI: http://yourdomain.com
   License: GPL
   */
   
   if (current_user_can('edit_pages') ) echo "Hi Admin!";
   
   ?>

   And here is the result:
   Fatal error: Call to undefined function wp_get_current_user() in D:\www\adspace\wp-includes\capabilities.php on line 1028

   Similar situation appears when calling any wordpress function or trying to use global variable (eg. global $current_user). I simply have no access to WP functions. Can you tell me why, please?

   Thanks for any advice,
   Martin

2. Ipstenu
   Half-Elf Support Rogue & Mod
   Posted 10 months ago #

   You need to toss global $current_user in there.

   <?php
   /*
   Plugin Name: Hello-World
   Plugin URI: http://yourdomain.com/
   Description: A simple hello world wordpress plugin
   Version: 1.0
   Author: martin
   Author URI: http://yourdomain.com
   License: GPL
   */
   
   global $current_user;
   if (current_user_can('edit_pages') ) echo "Hi Admin!";
   
   ?>

3. martinstrouhal
   Member
   Posted 10 months ago #

   Unfortunately this didn't help. I'm getting another error:
   Fatal error: Call to undefined function wp_get_current_user() in D:\www\adspace\wp-includes\capabilities.php on line 1039

   When I put this line
   if (current_user_can('edit_pages') ) echo "Hi Admin!";
   into a function and then call it from theme, it works, But i need to run this code in constructor of a class - and there it does not work.

   To make it simple: i cannot call any wordpress function in my plugin:-(

4. martinstrouhal
   Member
   Posted 10 months ago #

   (i have upgraded wordpess to 3.2.1 meanwhile, code still doesn't work)

5. martinstrouhal
   Member
   Posted 10 months ago #

   Another observation:
   that row of code is inside class constructor. If I call new instance of class inside main plugin file, it ends with error. But when I call constructor from theme, it works. It seems that wordpress functions are not "included" when plugin code is executed, but when theme code is executed, they are. Can this be true?

6. Ipstenu
   Half-Elf Support Rogue & Mod
   Posted 10 months ago #

   In part ... that's because you're not telling your plugin WHERE you want to output :) The rest is because you're not telling it HOW to output

   Look at Hello Dolly: http://svn.automattic.com/wordpress/trunk/wp-content/plugins/hello.php

   Cribbing this off the cuff...

   global $current_user;
   
   // This just echoes, we'll position it later
   function hello_world() {
   
   if (current_user_can('edit_pages') )
        {echo "<p id='hello-world'>Hello, Admin!</p>";}
   else
        {echo "<p id='hello-world'>Hello, User!</p>";}
   }
   
   // Now we set that function up to execute when the admin_notices action is called
   add_action( 'admin_notices', 'hello_world' );
   
   // We need some CSS to position the paragraph
   function world_css() {
   	// This makes sure that the positioning is also good for right-to-left languages
   	$x = is_rtl() ? 'left' : 'right';
   
   	echo "
   	<style type='text/css'>
   	#dolly {
   		float: $x;
   		padding-$x: 15px;
   		padding-top: 5px;
   		margin: 0;
   		font-size: 11px;
   	}
   	</style>
   	";
   }
   
   add_action( 'admin_head', 'world_css' );

   The major takeaway for you here is this:

   1) You can't just ECHO things in a plugin, you have to say when and where.
   2) We do this by creating functions and calling them in actions.

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