Shortcode not working in widget

Question

I created the following shortcode:

function newsletter_signup_shortcode( $atts ) {
$post_type = get_post_type();

// Attributes
extract( shortcode_atts(
    array(
        'location' => get_permalink(),
        'show_title' => 'yes',
    ), $atts )
);

// Return the unfiltered content if we're not on a post.
if ( $post_type != 'post' ) {
    return $content;
}

ob_start();
?>

<!-- MailChimp Signup Form outputs here - code omitted for clarity -->

<?php
// Add the opt-in form after the post content.
return $content . ob_get_clean();
}
add_shortcode( 'newsletter_signup', 'newsletter_signup_shortcode' );

This works great on the home page and blog post pages, within the post and in the sidebar widget.

However, when I view a page, the sidebar widget does not display the shortcode content:

What am I missing here?

Answer 1

You have a conditional in your function that will skip (return) if the current "view" is not a single post. You also have an undefined variable $content - the following has the condition removed and undefined variable fixed (always, always have debugging on when building with WordPress):

function newsletter_signup_shortcode( $atts ) {
    $post_type = get_post_type(); // Not sure if you still need this for your MailChimp template?

    // Attributes
    extract( shortcode_atts(
        array(
            'location' => get_permalink(),
            'show_title' => 'yes',
        ), $atts )
    );

    ob_start();
    ?>

    <!-- MailChimp Signup Form outputs here - code omitted for clarity -->

    <?php
    return ob_get_clean();
}