Default Featured Image

Yes, the following code will set a different image.

add_filter( 'dfi_thumbnail_id', 'dfi_posttype_book', 10, 2 ); function dfi_posttype_book( $dfi_id, $post_id ) { $post = get_post( $post_id ); if ( 'book' === $post->post_type ) { return 31; // the image id for the book post type. } return $dfi_id; // the original featured image id. }

Yes, the following snippet will set different images based on the category.

add_filter( 'dfi_thumbnail_id', 'dfi_category', 10, 2 ); function dfi_category( $dfi_id, $post_id ) { // Set a different image for posts that have the 'cats' category set. // This will trigger first, if multiple categories have been set. if ( has_category( 'cats', $post_id ) ) { return 7; // cats img id. } // Set a different image for posts that have the 'cats' category set. if ( has_category( 'dogs', $post_id ) ) { return 8; // dogs img id. } return $dfi_id; // the original featured image id. }

When a Default Featured Image is used it will already add an extra class default-featured-img . This can be used for styling.

If you need more you can change the whole HTML with the filter dfi_thumbnail_html .

add_filter( 'dfi_thumbnail_html', 'dfi_add_class', 10, 5 ); function dfi_add_class( $html, $post_id, $default_thumbnail_id, $size, $attr ) { // Add a class to the existing class list. $attr['class'] .= ' my-class'; return wp_get_attachment_image( $default_thumbnail_id, $size, false, $attr ); }

The following code will exclude the post/page with ID 23.

add_filter( 'dfi_thumbnail_id', 'dfi_skip_page', 10, 2 ); function dfi_skip_page( $dfi_id, $post_id ) { if ( $post_id == 23 ) { return 0; // invalid id. } return $dfi_id; // the original featured image id. }