include wp-blog-header not working on MAMP

Question

To clarify my question... My plugin is/was using AJAX to call the file pluginname/submit/pick.php My pluginname/pluginname.php contains the usual plugin header and wordpress automatically finds it.

Original Question... I'm trying to use the global $wpdb in a plugin to insert data into one of my tables. From the docs it sounds like I just need to include wp-blog-header.php However when I try to do so I'm getting an error.

PHP Fatal error: [require()](function.require) : Failed opening required 'http://localhost:8888/blog/wp-blog-header.php' (include_path='.:/Applications/MAMP/bin/php/php5.3.6/lib/php') in /Applications/MAMP/htdocs/blog/wp-content/plugins/pluginname/submit/pick.php on line 4

My pluginname/submit/pick.php (which is called by AJAX) has the following code

<?php
    $p = 'http://localhost:8888/blog/wp-blog-header.php';
    echo $p;
    require($p);
    echo 'hi';
?> 

If I load the pick.php, I see http://localhost:8888/blog/wp-blog-header.php and that is it. So it must be failing on the require, as the error log confirms.

The path is correct as I inserted a quick echo into wp-blog-header.php, and copy pasted the output from pick.php into the address bar and it worked.

Any help would be appreciated.

Answer 1

You're making something completely wrong.

Header comment

In your main file, you need the following comment on top (ex. taken from Contact form 7):

<?php
/*
Plugin Name: Contact Form 7
Plugin URI: http://contactform7.com/
Description: Just another contact form plugin. Simple but flexible.
Author: Takayuki Miyoshi
Author URI: http://ideasilo.wordpress.com/
Text Domain: wpcf7
Domain Path: /languages/
Version: 3.1.2
*/

WP will detect the plugin automagically. Then simply define/require/include what you need. The plugin will then be loaded just before the plugins_loaded hook, which is the first one available to you. You then can use the complete WP environment.

Answer 2

The short answer

The error is because I put a URL in instead of a filepath. and the one line fix is to set $p = '../../../../wp-blog-header.php';

The long answer

Following kaiser's link led me down a long road that eventually lead to what I believe is the correct way to do this.

in pluginname/plugin.php

// load your javascript, and setup the ajaxurl variable
// this is loading my js everywhere, we could load it only where needed
// 0.01 is the version of your js, increment this each time you change your js
//   so that you don't keep using the same cached version
wp_enqueue_script( 'pluginname', plugins_url( 'js/pluginname.js', __FILE__ ), array( 'jquery' ), 0.01 );
wp_localize_script( 'pluginname', 'pluginname', array( 'ajaxurl' => admin_url( 'admin-ajax.php' ) ) );

// wp_ajax_insert_pick is a combination of wp_ajax_ and the 'action' : 'insert_pick' you provide in your js
// ajax_insert_pick is the function below that is called to handle your ajax request 
add_action( "wp_ajax_action_name", "ajax_insert_pick" );

// this basically replaces pluginname/submit/pick.php
function ajax_insert_pick() {
    global $wpdb;
    $var = $_POST['var'];
    // handle the ajax request here
    echo $response;
    die(); // needed otherwise wordpress may append a zero to your response.
}

in pluginname/js/pluginname.js

function submit_pick( var ) {
    jQuery.post( pluginname.ajaxurl, 
                 { 'action' : 'insert_pick',
                   'var' : var },
                 function(response) {
                     alert(response); },
                 'text' );
}

Since I just learned this last night, and am only a month into learning php/mysql/wp/js/ajax there are quite possibly some errors in the above. But it worked for me last night, so I'm happy with it at this stage.