org-roam-buffer-p is a byte-compiled function defined in org-roam.el.

Signature
(org-roam-buffer-p &optional BUFFER)

Documentation
Return t if BUFFER is for an Org-roam file.

If BUFFER is not specified, use the current buffer.

This function has :before-until advice: md-roam-buffer-p.

References
References in org-roam.el:
(defun org-roam-buffer-list ...) 1 reference

Find all references Functions used by org-roam-buffer-p

Advice
This function is advised.

Debugging
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Disassemble Forget

Source Code
;; Defined in ~/.emacs.d/.local/straight/repos/org-roam/org-roam.el
(defun org-roam-buffer-p (&optional buffer)
 "Return t if BUFFER is for an Org-roam file.
If BUFFER is not specified, use the current buffer."
 (let ((buffer (or buffer (current-buffer)))
 path)
 (with-current-buffer buffer
 (and (derived-mode-p 'org-mode)
 (setq path (buffer-file-name (buffer-base-buffer)))
 (org-roam-file-p path)))))

Symbol Properties
defalias-fset-function
 #[128 "\300\301\302#\207"
 [apply advice--defalias-fset nil nil]
 5 nil]
 Disassemble
function-documentation
 (advice--make-docstring 'org-roam-buffer-p)

Cheers,
Annie
On Aug 8, 2023, 3:52 PM +0800, Ihor Radchenko <yantar92@posteo.net>, wrote:
Angela L <angeldjsyg@outlook.com> writes:

It’s nil

This is unexpected.
AFAIK, org-roam-buffer-p is defined as

(defun org-roam-buffer-p (&optional buffer)
"Return t if BUFFER is for an Org-roam file.
If BUFFER is not specified, use the current buffer."
(let ((buffer (or buffer (current-buffer)))
path)
(with-current-buffer buffer
(and (derived-mode-p 'org-mode)
(setq path (buffer-file-name (buffer-base-buffer)))
(org-roam-file-p path)))))

And it does check (derived-mode-p 'org-mode).

May you please post the information displayed in C-h f org-roam-buffer-p?

--
Ihor Radchenko // yantar92,
Org mode contributor,
Learn more about Org mode at <https://orgmode.org/>.
Support Org development at <https://liberapay.com/org-mode>,
or support my work at <https://liberapay.com/yantar92>