How to properly use “data:” with jquery ajax request?

Question

My code inside of function deletePost is not executing. This is because the contents of $_GET['title'] is empty. I set the value of the title in the ajax using this line postTitle: $(this).siblings("h3.blog").text() how come the value doesn't make it through the the php script?

index.php

<?php
        include 'scripts/db_connect.php';
        include 'scripts/functions.php';
        sec_session_start();
        $sql = "SELECT * FROM blog";
        $result = mysqli_query($mysqli, $sql);
        while($row = mysqli_fetch_array($result))
        {
            echo'<div class="blog"><h3 class="blog">' . $row['Title'] . "</h3><h3>" . $row['Date'] . "</h3><h3>" . $row['Tag'] . "</h3><hr>";
                echo'<p class="blog">' . $row['Body'] . '</p><form name="postForm" method="post" action="process_post.php">
              <input type="radio" name="postAction" value="editPost" class="editPost" type="button">Edit</input>
              <input type="radio" name="postAction" value="deletePost" class="deletePost" type="button">Delete</input>
              <input type="radio" name="postAction" value="commentPost" class="commentPost" type="button">Comment</input></form></div>';
        }

        ?>

What am I doing wrong with $_GET and the data from ajax?

JavaScript

$('.deletePost').click(function(){
    $.ajax({
        url:"scripts/post_action.php",
        data: {action: "deletePost",  postTitle: $(this).siblings("h3.blog").text()},
    });
});

post_action.php

<?php
include 'db_connect.php';
include 'functions.php';
if($_GET['action'] == "deletePost")
        deletePost($mysqli, $_GET['postTitle']);
function deletePost($mysqli, $title){
    $sql = "DELETE FROM blog WHERE Title = '$title'";
    mysqli_query($mysqli, $sql);
}
?>

Answer 1

This is because the contents of $_GET['title'] is empty.

The h3.blog element is not a sibling of the delete button. It's a sibling of the parent of the delete button (the form element). To be flexible with your layout, you can use .closest (traverse up) with .find (traverse down):

$(this).closest('div.blog').find('h3.blog').text()

Answer 2

You have extra single quote. Try to write:

function deletePost($mysqli, $title){
    $sql = "DELETE FROM blog WHERE Title =" . $title;
    mysqli_query($mysqli, $sql);
}

Also your code not protected from sql injection.