Function convertToLegalXml

frontend/lib/utils.ts:64–107

(xmlString: string)

 * @returns A legal XML string with properly closed tags and removed incomplete mxCell elements.
 */
export function convertToLegalXml(xmlString: string): string {
    // This regex will match either self-closing <mxCell .../> or a block element
    // <mxCell ...> ... </mxCell>. Unfinished ones are left out because they don't match.
    const regex = /<mxCell\b[^>]*(?:\/>|>([\s\S]*?)<\/mxCell>)/g
    let match: RegExpExecArray | null
    let result = "<root>\n"

    while ((match = regex.exec(xmlString)) !== null) {
        // match[0] contains the entire matched mxCell block
        let cellContent = match[0]

        // Remove orphaned <mxPoint> elements that are directly inside <mxGeometry>
        // without an 'as' attribute (like as="sourcePoint", as="targetPoint")
        // and not inside <Array as="points">
        // These cause "Could not add object mxPoint" errors in draw.io
        // First check if there's an <Array as="points"> - if so, keep all mxPoints inside it
        const hasArrayPoints = /<Array\s+as="points">/.test(cellContent)
        if (!hasArrayPoints) {
            // Remove mxPoint elements without 'as' attribute
            cellContent = cellContent.replace(
                /<mxPoint\b[^>]*\/>/g,
                (pointMatch) => {
                    // Keep if it has an 'as' attribute
                    if (/\sas=/.test(pointMatch)) {
                        return pointMatch
                    }
                    // Remove orphaned mxPoint
                    return ""
                },
            )
        }

        // Indent each line of the matched block for readability.
        const formatted = cellContent
            .split("\n")
            .map((line) => "    " + line.trim())
            .filter((line) => line.trim()) // Remove empty lines from removed mxPoints
            .join("\n")
        result += formatted + "\n"
    }
    result += "</root>"

    return result
}

/**
 * Wrap XML content with the full mxfile structure required by draw.io.