       (org-map-entries
        (lambda ()
          (hide-subtree))
-       "EXPORT_FILE_NAME<>\"\""))
+       "EXPORT_FILE_NAME<>\"\"|CUSTOM_ID<>\"\""))
     ;; Also hide Footnotes and comments.
     (save-excursion
       (goto-char (point-min))

(with-eval-after-load 'org
  (defun modi/org-hugo-collapse-all-posts ()
    "Collapse all post subtrees in the current Org file.
Also collapse the Footnotes subtree and COMMENT subtrees if
present.

A post subtree is one that has the EXPORT_FILE_NAME property set."
    (interactive)
    (widen)
    (org-show-all '(headings))

;; Time-stamp: <2018-10-01 11:22:25 kmodi>

;; Hugo
;; https://gohugo.io
