How to call php class method using ajax

Question

I'm new to ajax. I'm trying to call get_mother method through ajax in my form textbox change event. I want to show results in datalist. below is the code i have used.

class ChildApplication extends Application{
function __construct(){
    $this->login_required();
}
function get_mother(){
    $mother = $_POST['mother_name'];
    $mother = '%'.$mother.'%';
    $db=$this->get_dbo();
    $sql = "SELECT * FROM tbl_mother WHERE `mother_fname` LIKE ? ";
    $results = $db->load_result($sql,array($mother));
    return $results;
}
function get_child($mother){
 //statements 
}
}

My script is:

   $(document).ready(function(){
     $("#mother_name").keyup(function(event){
        event.preventDefault();
         var mother = $("#mother_name").val();
         $.ajax({
            type: 'POST',
            url: 'applications/child/child.php',
            data: dataString,
            dataType: 'json',
            success: function(){
                alert("pass");
            },
            error: function(){
                alert("error");
            }
            });

           });
         });

none of alerts are displayed. please help me to solve the problem

Answer 1

I guess that "dataString" variable is not defined. I think that you should replace the value of "data" like this:

data: {mother_name: mother},

Also make sure that the function get_mother() is called in "applications/child/child.php"

$ChildApplication = new ChildApplication;
$ChildApplication->get_mother();