Unable to get Post meta in plugins - wordpress

Question

I'm Trying to make a plugin that send emails with the post content to an email when admin
check the check box. I found some codes and trying to do this
The plugin creates meta box with check box custom field.
Problem:
Not able to get custom field value in the plugin using get_post_meta to check whether to send the email or not
Following is the code:
add_action('admin_init','add_metabox_post_sidebar');
add_action('save_post','save_metabox_post_sidebar');
/*
* Funtion to add a meta box to enable/disable the posts.
*/
function add_metabox_post_sidebar()
{
add_meta_box("Enable Sidebar", "Enable Sidebar", "enable_sidebar_posts", "post", "side", "high");
}
function enable_sidebar_posts(){
global $post;
$check=get_post_custom($post->ID );
$checked_value = isset( $check['post_sidebar'] ) ? esc_attr( $check['post_sidebar'][0] ) :
'no';
?>
<label for="post_sidebar">Enable Sidebar:</label>
<input type="checkbox" name="post_sidebar" id="post_sidebar" <?php if($checked_value=="yes")
{echo "checked=checked"; } ?> >
<?php
}
/*
* Save the Enable/Disable sidebar meta box value
*/
function save_metabox_post_sidebar($post_id)
{
// Bail if we're doing an auto save
if( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) return;
// if our current user can't edit this post, bail
if( !current_user_can( 'edit_post' ) ) return;
$checked_value = isset( $_POST['post_sidebar'] ) ? 'yes' : 'no';
update_post_meta( $post_id, 'post_sidebar', $checked_value );
}
// Function that runs when a post is published
function run_when_post_published( $post ) {
$author = get_userdata($post->post_author);
$category = get_the_category();
$author_id = $post->post_author;
$author = get_the_author_meta( 'nickname', $author_id );
$title = get_the_title();
$permalink = get_permalink();
$featured = get_the_post_thumbnail_url();
$email_subject = $title;
$message = apply_filters( 'the_content', $post->post_content );
$message2=wp_strip_all_tags($message);
$message3= html_entity_decode($message2);
$headers = 'Manarty <info#example.com>';
global $wp_query;
$thePostID = $wp_query->post->ID;
$k=get_post_meta( $thePostID, 'post_sidebar', true);
if(!empty($k) ) {
$email = 'test#test.com';
wp_mail( $email, $email_subject, $message3 );
}
}
// Makes sure email only gets sent the first time a post is published
add_action('new_to_publish', 'run_when_post_published');
add_action('draft_to_publish', 'run_when_post_published');
add_action('pending_to_publish', 'run_when_post_published');

Answer 1

It think your problem might be here:
$k=get_post_meta( $thePostID, 'post_sidebar', true);
if in fact you already had saved 'post_sidebar' correctly it means that you don't have the correct value of $thePostID
Instead of your code try this, it works for me:
global $post;
$currentPostObject = $post;
$currentPostObjectID = $currentPostObject->ID;