Last Updated Time in sitemap.xml

Describe the bug

When generating sitemap, the lastmod attribute only uses the commit time in git log, but not lastUpdated value in frontmatter.

Reproduction

No need to add any templates.

Expected behavior

If the frontmatter contains lastUpdated key, generated sitemap should use the lastUpdated value, otherwise use the commit time in git log.

I remember the behavior was right in RC versions, not very sure.

System Info

System:
  OS: Windows 11 10.0.22631
  CPU: (24) x64 13th Gen Intel(R) Core(TM) i7-13700K
  Memory: 52.88 GB / 63.77 GB
Binaries:
  Node: 20.12.2 - D:\Program Files\nodejs\node.EXE
  npm: 10.5.0 - D:\Program Files\nodejs\npm.CMD
Browsers:
  Edge: Chromium (125.0.2535.67)
  Internet Explorer: 11.0.22621.3527
npmPackages:
  vitepress: ^1.2.2 => 1.2.2

Additional context

No response

Validations

[x] Check if you're on the latest VitePress version.
[x] Follow our Code of Conduct
[x] Read the docs.
[x] Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.

Solution (Added in 3rd June 2024)

I wrote some codes to solve this issue, maybe I can help others who searched from google.

in config.mjs or config.mts:

import fs from "fs";

export default defineConfig({
    sitemap: {
        hostname: "Your Domain",
        transformItems: (items) => {
            // Reset last updated time of sitemap.xml
            items.forEach(item => {
                const url = item.url;
                // Read the file, replace the updated time from frontmatter with the time in git log
                // My blog path is "/docs", you can replace it to yours.
                const file = "docs/" + url + ".md";
                try {
                    const data = fs.readFileSync(file, "utf-8");
                    const getUrl = data => {
                        const allLines = data.split("\n");
                        for (let i = 0; i < allLines.length; i++) {
                            const currentLine = allLines[i];
                            // the statement i > 1 can prevent the program from suspending when reading at the first line
                            if (i > 1 && currentLine === "---") {
                                console.warn("There is no lastUpdated time in Frontmatter.");
                                return null;
                            }
                            if (currentLine.indexOf("lastUpdated") >= 0) {
                                return currentLine.replace("lastUpdated:", "").trim();
                            }
                        }
                    }
                    const newUpdatedTime = getUrl(data);
                    // Only replace updated time when frontmatter value exists.
                    if (newUpdatedTime) {
                        item.lastmod = newUpdatedTime;
                    }
                } catch (err) {
                    console.error(err);
                    return false;
                }
            });
            return filteredItems;
        }
    },
});

vuejs / vitepress

Last Updated Time in sitemap.xml #3931