gatsby-rss.js

const rss = {
  resolve: `gatsby-plugin-feed`,
  options: {
    query: `
        {
          site {
            siteMetadata {
              title
              description
              siteUrl
              site_url: siteUrl
            }
          }
        }
      `,
    feeds: [
      {
        serialize: ({ query: { site, allMdx } }) => {
          return allMdx.edges.map(edge => {
            return Object.assign({}, edge.node.frontmatter, {
              description: edge.node.excerpt,
              date: edge.node.frontmatter.date,
              url: site.siteMetadata.siteUrl + edge.node.fields.slug,
              guid: site.siteMetadata.siteUrl + edge.node.fields.slug,
              custom_elements: [{ "content:encoded": edge.node.html }],
            })
          })
        },
        query: `
            {
              allMdx(
                sort: { order: DESC, fields: [frontmatter___date] },
              ) {
                edges {
                  node {
                    excerpt
                    body
                    fields { slug }
                    frontmatter {
                      title
                      date
                    }
                  }
                }
              }
            }
          `,
        output: "/rss.xml",
        title: "My blog's RSS Feed",
        // optional configuration to insert feed reference in pages:
        // if `string` is used, it will be used to create RegExp and then test if pathname of
        // current page satisfied this regular expression;
        // if not provided or `undefined`, all pages will have feed reference inserted
        // match: "^/blog/",
        // optional configuration to specify external rss feed, such as feedburner
        // link: "https://feeds.feedburner.com/gatsby/blog",
      },
    ],
  },
}

module.exports = rss