Using multiple line variable inside a function?

Question

I am using the commenting system to all users to add a private note that only they can see to posts and I am using the wordpress comments system to do it. I wrote a function to call the logged in user comments in a shortcode to display on their profile page. I can get this to work without passing it through a variable but it always shows up at the top of the page. I can't seem to call these variables inside the function. All I get is a blank page. Please take a look and tell me what I am doing wrong.

function notes_by_comments() {

global $wpdb;

$current_user = wp_get_current_user();

$note_content = '<h5 style="border-bottom: 1px solid #DADADA; padding-bottom: 7px;padding-top: 25px;"><strong>Notes</strong></h5>';

$commentQuery = "SELECT * from $wpdb->comments WHERE user_id=$current_user->ID ORDER BY   comment_date DESC LIMIT 0 ,5";

$comments = $wpdb->get_results($commentQuery);
foreach ($comments as $comment) {

$note_content. = '<li><b>Note for</b> <a href="'. get_permalink($comment- >comment_post_ID). '#comment-'.$comment->comment_ID .'">';
$note_content. = get_the_title($comment->comment_post_ID) . '</a> -'; 

 if(get_post_type( $comment->comment_post_ID ) === 'for_sale_listings'){
 $note_content. =  "<b>Sale Listing</b>";
} elseif (get_post_type( $comment->comment_post_ID ) === 'rental_listings'){
$note_content. = "<b>Rental Listing</b>";
} elseif (get_post_type( $comment->comment_post_ID ) === 'roomate_share'){
$note_content. = "<b>Roommate Share</b>";
}

$note_content. = '<p>' . $comment->comment_content . '</p></li>';

return $note_content;

} 
}

add_shortcode('notes', 'notes_by_comments'); 

Answer 1

Could be because you are using the concatenating assignment operator incorrectly:

$note_content. =

should be

$note_content .=

http://php.net/manual/en/language.operators.string.php

Answer 2

I reformat your code a bit. Please always use $wpdb->prepare() for SQL queries. The switch-case is a bit better solution than this if-elseif-elseif-elseif-else-tadada.

I have not tested the code, I did not have a copy of your database, but you put the return inside the foreach loop. Maybe this was the error.

<?php
function notes_by_comments() {

    global $wpdb;

    $current_user = wp_get_current_user();
    $note_content = '<h5 style="border-bottom: 1px solid #DADADA; padding-bottom: 7px;padding-top: 25px;"><strong>Notes</strong></h5>';

    $commentQuery = $wpdb->prepare(
        'SELECT * from $wpdb->comments WHERE user_id=%d ORDER BY %s DESC LIMIT 0 ,5',
        $current_user->ID,
        comment_date
    );

    $comments = $wpdb->get_results( $commentQuery );

    foreach ( $comments as $comment ) {
        $note_content = '';

        $note_content .= sprintf( '<li><b>Note for</b> <a href="%s#comment-%d">',
            get_permalink( $comment->comment_post_ID ),
            $comment->comment_ID
        ); 

        $note_content .= get_the_title( $comment->comment_post_ID ) . '</a> -'; 

        switch ( get_post_type( $comment->comment_post_ID ) ) {

            case 'for_sale_listings':
                $note_content .=  "<b>Sale Listing</b>";
                break;

            case 'rental_listings':
                $note_content .= "<b>Rental Listing</b>";
                break;

            case 'roomate_share':
                $note_content .= "<b>Roommate Share</b>";
                break;

            default:
                $note_content .= '';
        }

        $note_content .= sprintf( '<p>%s</p></li>', $comment->comment_content );

    }

    return $note_content;

}

add_shortcode( 'notes', 'notes_by_comments' ); 

A well formated code with indents is always usefull to find errors.