Panowie mam pytanko jak moge się dostac do metody w klasie tak abym mogl przekazac w url`u dla zapytania ajaxowego?

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$.ajax({
	type:"post",
	url: ,
	success:function(data){
	}
    });
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Udalo mi sie zrobic takie cos:
plik rw-ajax-search

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function rwas_show_searcher() {
    echo '<script src="//ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>';
    ?>
        <script type='text/javascript'>
        $(document).ready(function(){
 
    	$('#submit').on('click', function(event){
 
    	    $.ajax({
    		type:'POST',
    		url: "<?php echo plugins_url("rwas_show.php", __FILE__) ?>",
    		dataType: 'html',
    		success:function(data){
    		    $('#result').html(data);
    		}
 
    	    });
    	    event.preventDefault();
    	});
        });
    </script>
    <?php
    echo "<form method='post' action=''>";
 
    echo "<input type='checkbox' name='filter_date' id='filter_date'/>";
 
    echo "<br>";
 
    echo "<input type='text' name='search' id='search'/>";
 
    echo "<input type='submit' name='submit' value='Szukaj' id='submit' />";
 
    echo "</form>";
 
    echo "<ul id='result'></ul>";
 
}
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plik rwas_show.php

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define('RWAS_PATH', dirname(__FILE__));
require RWAS_PATH . '/model/RwAjaxSearch.php';
$model = new RwAjaxSearch();
$result = $model->show_result();
 
foreach ($result as $row) {
    echo $row['ID'] . "<br>";
} 
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plik RwAjaxSearch

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class RwAjaxSearch {
 
    private $tableName;
    private $wpdb;
    public function __construct() {
        global $wpdb;
        $prefix = $wpdb->prefix;
        $this->tableName = $prefix . "posts";
        $this->wpdb = $wpdb;
    }
 
    public function show_result(){
	$query = "SELECT * FROM  wp_" . $this->tableName . " ORDER BY id DESC;";
        return $this->wpdb->get_results($query, ARRAY_A);
 
    }
 
 
}
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i po wyslaniu rzadania otrzymuje:

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Notice: Trying to get property of non-object in C:\xampp\htdocs\wp\wp-content\plugins\rw-ajax-search\model\RwAjaxSearch.php on line 8
 
Fatal error: Call to a member function get_results() on a non-object in C:\xampp\htdocs\wp\wp-content\plugins\rw-ajax-search\model\RwAjaxSearch.php on line 15
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ocb? Tzn wiem co to za blad ale dlaczego on wystapil