New feature: UI for the "link" post meta

Hi Dean Oakley,

I have created an new functionality that you might like. I needed an user interface to add the link post meta for my users. This is what I came up with. View a screenshot (Dutch!).
The text says:

The following URL makes the full slide clickable.
Enter the URL manually or select a page below. Leave the field empty to disable the link.
Selecting a page will overwrite the manually entered URL when post is updated.

Users can type the URL themselves, or select a page from the drop down.

Instruction:
At the very end of “bannerspace.php” add:

// If in administrator back-end, load the post meta box
if (is_admin()) {
	require_once('bm_admin_meta_box.php');
}

Create a new file, named “bm_admin_meta_box.php” and paste the following code:

<?php

/* Define the custom box */
add_action( 'add_meta_boxes', 'bm_bs_add_post_meta_box' );

/* Do something with the data entered */
add_action( 'save_post', 'bm_bs_post_meta_box_save' );

/* Adds a box to the main column on the Post and Page edit screens */
function bm_bs_add_post_meta_box() {
	add_meta_box(
		'bm_bs_add_post_meta_box_id',
		__('Bannerspace full slide hyperlink'),
		'bm_bs_post_meta_box_html',
		'bannerspace_post'
	);
}

/* Prints the box content */
function bm_bs_post_meta_box_html( $post ) {

	// Use nonce for verification
	wp_nonce_field( plugin_basename( __FILE__ ), 'bm_bs_post_meta_nonce' );

	// The actual fields for data entry
	// Use get_post_meta to retrieve an existing value from the database and use the value for the form
	$value = get_post_meta( $post->ID, 'link', true );
	?>
	<p>
		<label for="bm_bs_post_meta_box_link">
		<?php _e('The following URL makes the full slide clickable.<br />Enter the URL manually or select a page below. Leave the field empty to disable the link.'); ?>
		</label><br />
		<input type="text" id="bm_bs_post_meta_box_link" name="bm_bs_post_meta_box_link" value="<?php echo esc_attr($value) ?>" style="width:100%" />
	</p>

	<p>
		<label for="bm_bs_post_meta_box_page">
		<?php _e('Selecting a page will overwrite the manually entered URL when post is updated.', 'bannerspace'); ?>
		</label><br />
		<?php 

			// Prepare the arguments
			$args = array (
				'name' => 'bm_bs_post_meta_box_page',
				'show_option_none' => __('Select a page', 'bannerspace'),
				'option_none_value' => '0',
			);

			// Get the pages from the content site
			wp_dropdown_pages( $args );

		?>
	</p>
	<?php
}

/* When the post is saved, saves our custom data */
function bm_bs_post_meta_box_save( $post_id ) {

	// First we need to check if the current user is authorised to do this action.
	if ( 'bannerspace_post' != $_REQUEST['post_type'] ) {
		// Only edit post_type "bannerspace_post"
		return;
	} else {
		if ( ! current_user_can( 'edit_post', $post_id ) )
			return;
	}

	// Secondly we need to check if the user intended to change this value.
	if ( ! isset( $_POST['bm_bs_post_meta_nonce'] ) || ! wp_verify_nonce( $_POST['bm_bs_post_meta_nonce'], plugin_basename( __FILE__ ) ) )
	return;

	// Thirdly we can save the value to the database

	//if saving in a custom table, get post_ID
	$post_ID = $_POST['post_ID'];

	//sanitize user input
	$post_meta_page_id = (int)$_POST['bm_bs_post_meta_box_page'];

	if ($post_meta_page_id > 0) {
		$post_meta_link = get_permalink( $post_meta_page_id );

		// Replace to real domain, if needed
		// Used with WP Multi-site and WordPress MU Domain Mapping plugin.
		if (function_exists('domain_mapping_post_content'))	{
			$post_meta_link = domain_mapping_post_content($post_meta_link);
		}
	} else {
		$post_meta_link = sanitize_text_field( $_POST['bm_bs_post_meta_box_link'] );
	}

	// Update post meta
	add_post_meta($post_ID, 'link', $post_meta_link, true) or
	update_post_meta($post_ID, 'link', $post_meta_link);
}

http://wordpress.org/plugins/bannerspace/