TinyMCE editor - new lines not rendered on front end

Question

I've been working with a plugin making various tweaks and adding additional functionality.

It uses custom post type to create a page with an associated download. In the admin area which allows you to create these new downloads, there is a box which allows you to add/edit a description for the download. This serves as the body content for the rendered page.

However, the admin page only had a standard for this which was created by the following code;

    public function display_sdm_description_meta_box($post) {  // Description metabox
_e('Add a description for this download item.', 'sdm_lang');
echo '<br /><br />';

$old_description = get_post_meta($post->ID, 'sdm_description', true);
?>
<textarea id="sdm_description" name="sdm_description" style="width:60%;height:100px;"><?php echo $old_description; ?></textarea>
<?php
wp_nonce_field('sdm_description_box_nonce', 'sdm_description_box_nonce_check');

}

I needed this to give the typical WP editor functionality so that the end user can create the page / body content much the same as on a normal page or post. As a result I was given the following code via another question I posted here on SO.

$old_description = get_post_meta($post->ID, 'sdm_description', true); 
$editor_id = 'sdm_description';
$settings = array( 'media_buttons' => false );

wp_editor( $old_description , $editor_id, $settings );

So I now have;

public function display_sdm_description_meta_box($post) {  // Description metabox
    _e('Add a description for this download item.', 'sdm_lang');
    echo '<br /><br />';

    $old_description = get_post_meta($post->ID, 'sdm_description', true);

    //adds TinyMCE capabilities
    $editor_id = 'sdm_description';
    $settings = array( 'media_buttons' => false );
    wp_editor( $old_description , $editor_id, $settings );

    ?>
    <!--<textarea id="sdm_description" name="sdm_description" style="width:60%;height:500px;"><?php echo $old_description; ?></textarea>-->
    <?php
    wp_nonce_field('sdm_description_box_nonce', 'sdm_description_box_nonce_check');
}

This render the tinyMCE editor in the admin section. However, if I hit enter to add a new line to the content this is only rendered as   on the front end. Multiple 'enters' just result in more spaces, but never a new line or the equivalent of <br/>

Why isnt the content output as expected? How can it be fixed?

Thanks in advance!

--- EXTRA INFO

If i click the 'Tools' > 'Source' button on the TinyMCE editor I get a pop up windows showing the content I've created as being: <p>This is a test</p><p>Another line of testing!!!</p>

However on the front-end [eg the website] the source code shows as: `This is a test

Another line of testing!!!`

If I go into the DB, I can see that the data is stored literally like this:

This is a test

 

 

Another line of testing!!!

Answer 1

As mentioned in the comments, this is a lack of wp_autop() and other formatting functions that get applied to the the_content filter. The editor does not save <p> tags at all, but later on line-breaks are converted into paragraphs via wp_autop().

For meta content, I like to recreate the default filters. I do this because some plugins add things via the the_content filter, Once I had apply_filters('the_content', $your_meta_content); for all my meta fields and ended up with 20 sets of social sharing buttons.

/* 
 * Recreate the default filters on the_content
 * this will make it much easier to output the meta content with proper/expected formatting
*/
add_filter( 'meta_content', 'wptexturize'        );
add_filter( 'meta_content', 'convert_smilies'    );
add_filter( 'meta_content', 'convert_chars'      );
add_filter( 'meta_content', 'wpautop'            );
add_filter( 'meta_content', 'shortcode_unautop'  );
add_filter( 'meta_content', 'prepend_attachment' );
add_filter( 'meta_content', 'do_shortcode');

Then where you actually wish to display your new data, you should write the following:

$description = get_post_meta($post->ID, 'sdm_description', true);
echo apply_filters( 'meta_content', $description );