flxzt/rnote · warning · anyhow::Error

Could not parse text as page number, parsing error

Error message

Could not parse text as page number, parsing error: {e:?}

What it means

Thrown by `parse_page_text` when `text.parse::<usize>()` fails outright — the entry text is not a non-negative integer (e.g. letters, negative sign, empty or oversized value). The `ParseIntError` is included in debug form to aid debugging; the caller must supply numeric page text.

Solutions

Enter a plain positive integer (e.g. "2") in the page field.
Restrict the entry input to digits (GtkEntry input filter) so non-numeric text cannot be entered.
Trim whitespace and strip non-digit characters before parsing.
Handle the Err branch by resetting the entry to the current valid page instead of propagating the error.

Example fix

// before
Err(e) => Err(anyhow::anyhow!(
    "Could not parse text as page number, parsing error: {e:?}"
)),
// after
Err(e) => {
    tracing::debug!("invalid page input: {e:?}");
    Ok(current_page) // fall back to the previously valid page
}

Defensive patterns

Strategy: validation

Validate before calling

let cleaned = text.trim();
if cleaned.is_empty() || !cleaned.chars().all(|c| c.is_ascii_digit()) {
    return Err(anyhow!("page input must be a positive integer"));
}

Type guard

fn is_page_text(text: &str) -> bool {
    let t = text.trim();
    !t.is_empty() && t.chars().all(|c| c.is_ascii_digit())
}

Try / catch

match text.trim().parse::<usize>() {
    Ok(p) => use_page(p),
    Err(_) => reset_entry_to_current_page(),
}

Prevention

Restrict the page entry to digit-only input
Trim whitespace and strip non-digits before parsing
Fall back to the current valid page on parse failure instead of propagating

When it happens

Trigger: In `update_paintable_content`, the page entry contains non-numeric text — empty string, "abc", "-1", "3.5", or a number exceeding usize — and `parse_page_text` attempts the parse.

Common situations: User typed letters or a negative/decimal number into the page field; entry pre-filled with placeholder text; paste of text like "Page 3".

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

AI-assisted analysis of flxzt/rnote@bbc5354502 (2026-09-08). Data as JSON: /api/errors/17d6c2750e8ebdff. Report an issue: GitHub.

Appendix: source

Thrown at crates/rnote-ui/src/strokecontentpreview.rs:219

                }
                Ok(_) | Err(_) => {
                    // user facing page number is 1 indexed
                    self.page_entry.set_text(&(current_page + 1).to_string());
                }
            }
            self.n_pages_button.set_label(&n_pages.to_string());
        }
    }

    fn parse_page_text(text: &str, n_pages: usize) -> anyhow::Result<usize> {
        // user facing page number is 1 indexed
        let page_range = 1..=n_pages;
        match text.parse::<usize>() {
            Ok(page) if page_range.contains(&page) => Ok(page - 1),
            Ok(page) => Err(anyhow::anyhow!(
                "Could not parse text as page number, '{page}' outside valid range '{page_range:?}'.",
            )),
            Err(e) => Err(anyhow::anyhow!(
                "Could not parse text as page number, parsing error: {e:?}"
            )),
        }
    }
}

glib::wrapper! {
    pub(crate) struct RnStrokeContentPreview(ObjectSubclass<imp::RnStrokeContentPreview>)
        @extends Widget,
        @implements gtk4::Accessible, gtk4::Buildable, gtk4::ConstraintTarget;
}

impl Default for RnStrokeContentPreview {
    fn default() -> Self {
        Self::new()
    }
}

View on GitHub (pinned to bbc5354502)