flxzt/rnote · error

DocExportFormat try_from

Error message

DocExportFormat try_from::<u32>() for value {} failed

What it means

DocExportFormat implements TryFrom<u32> via num_traits::FromPrimitive; a u32 with no matching variant yields this error. It guards numeric export-format identifiers (e.g. png, svg, pdf) read from preferences or IPC.

Solutions

1. Validate the u32 against the defined DocExportFormat variants before conversion.
2. Use the current rnote version's enum ordering; migrate values from older files.
3. Default to a safe format (e.g. PNG) on conversion failure.
4. Persist formats by name instead of integer discriminant.

Example fix

// before
let format = DocExportFormat::try_from(raw_u32)?;
// after
let format = DocExportFormat::try_from(raw_u32)
    .unwrap_or(DocExportFormat::Png);

fn is_valid_doc_export_format(v: u32) -> bool {
    DocExportFormat::try_from(v).is_ok()
}

fn as_doc_export_format(v: u32) -> Option<DocExportFormat> {
    num_traits::FromPrimitive::from_u32(v)
}

match DocExportFormat::try_from(raw) {
    Ok(f) => f,
    Err(_) => {
        log::warn!("unknown export format {raw}; defaulting to PNG");
        DocExportFormat::Png
    }
}

When it happens

Trigger: Calling DocExportFormat::try_from(u32) with an invalid value, typically during export flows that deserialize the requested format from stored prefs or frontend calls.

Common situations: Preferences saved by another rnote version with different discriminants, corrupted settings, or frontends passing out-of-range integer format codes.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• DocPagesExportFormat try_from
• SelectionExportFormat try_from
• PatternStyle try_from
• PredefinedFormat try_from
• MeasureUnit try_from

AI-assisted analysis of flxzt/rnote@bbc5354502 (2026-09-08). Data as JSON: /api/errors/69dc68aa6214acf0. Report an issue: GitHub.

Appendix: source

Thrown at crates/rnote-engine/src/engine/export.rs:52

    Svg,
    #[serde(rename = "pdf")]
    Pdf,
    #[serde(rename = "xopp")]
    Xopp,
}

impl Default for DocExportFormat {
    fn default() -> Self {
        Self::Pdf
    }
}

impl TryFrom<u32> for DocExportFormat {
    type Error = anyhow::Error;

    fn try_from(value: u32) -> Result<Self, Self::Error> {
        num_traits::FromPrimitive::from_u32(value).ok_or_else(|| {
            anyhow::anyhow!(
                "DocExportFormat try_from::<u32>() for value {} failed",
                value
            )
        })
    }
}

impl DocExportFormat {
    /// File extension for the format.
    pub fn file_ext(self) -> String {
        match self {
            DocExportFormat::Svg => String::from("svg"),
            DocExportFormat::Pdf => String::from("pdf"),
            DocExportFormat::Xopp => String::from("xopp"),
        }
    }
}

View on GitHub (pinned to bbc5354502)