How to format Contentful Rich Text to readable html for RSS feeds?

Question

Summary

I'm trying to figure out how to format Contentful JSON data to readable HTML for my RSS feeds on my website. I'm working in my gatsby-config.js file, so i cannot import any plugins. So I need to have a work around.

Relevant information

When I use // 'content:encoded': JSON.stringify(edge.node.body.json) it shows me the data but its unformatted.

This is the code in my gatsby-config.js:

(I've commented out the content:encoded and it gave me the description back in production mode, what is a good thing. But I cannot get to the point of showing the whole blog with the json blog content as well.

{
      resolve: `gatsby-plugin-feed`,
      options: {
        query: `
          {
            site {
              siteMetadata {
                title
                author
                description
                email
                siteUrl
                site_url: siteUrl
              }
            }
          }
        `,

        setup: ({ query: { site } }, options) => ({
          ...options,
          title: "Gimmix' RSS Feed",
          description: site.siteMetadata.description,
          site_url: site.siteMetadata.siteUrl,
          feed_url: `${site.siteMetadata.siteUrl}/rss.xml`,
          image_url: 'https://i.postimg.cc/JnqZPb3f/Gx-FAVICON.png',
          webMaster: `${site.siteMetadata.author} ${site.siteMetadata.email}`,
          managingEditor: site.siteMetadata.author,
          copyright: `${new Date().getFullYear()} ${site.siteMetadata.title}`,
          language: 'nl',
          generator: 'GatsbyJS',
          custom_namespaces: {},
          custom_elements: [{}],
        }),

        feeds: [
          {
            serialize: ({ query: { site, allContentfulBlogPost } }) => {
              return allContentfulBlogPost.edges.map((edge) => {
                return {
                  title: edge.node.title,
                  author: site.siteMetadata.author,
                  description: edge.node.subtitle,
                  date: edge.node.publishedDate,
                  url: `${site.siteMetadata.siteUrl}/blog/${edge.node.slug}`,
                  guid: `${site.siteMetadata.siteUrl}/blog/${edge.node.slug}`,
                  custom_elements: [
                    {
                      // 'content:encoded': edge.node.body.json,
                    },
                  ],
                };
              });
            },
            query: `
              {
                allContentfulBlogPost(sort: { fields: publishedDate, order: DESC }) {
                  edges {
                    node {
                      title
                      subtitle
                      slug
                      publishedDate
                      body {
                        json
                      }
                    }
                  }
                }
              }
            `,

            output: '/rss.xml',
            title: "Gimmix' 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/GimmixWMB',
          },
        ],
      },
    },

Environment

live project: https://gimmix.nl

rss xml link: https://gimmix.nl/rss.xml

feedburner (live rss feeds): https://feeds.feedburner.com/GimmixWMB

System:
    OS: macOS 10.15.7
    CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Shell: 5.7.1 - /bin/zsh
  Binaries:
    Node: 13.11.0 - ~/.nvm/versions/node/v13.11.0/bin/node
    Yarn: 1.22.10 - /usr/local/bin/yarn
    npm: 6.14.8 - ~/.nvm/versions/node/v13.11.0/bin/npm
  Languages:
    Python: 2.7.16 - /usr/bin/python
  Browsers:
    Chrome: 86.0.4240.75
    Safari: 14.0
  npmPackages:
    gatsby: ^2.24.73 => 2.24.73
    gatsby-image: ^2.4.21 => 2.4.21
    gatsby-plugin-canonical-urls: ^2.3.13 => 2.3.13
    gatsby-plugin-catch-links: ^2.3.15 => 2.3.15
    gatsby-plugin-eslint: ^2.0.8 => 2.0.8
    gatsby-plugin-feed: ^2.5.14 => 2.5.14
    gatsby-plugin-google-analytics: ^2.3.17 => 2.3.17
    gatsby-plugin-google-tagmanager: ^2.3.15 => 2.3.15
    gatsby-plugin-manifest: ^2.4.34 => 2.4.34
    gatsby-plugin-netlify: ^2.3.17 => 2.3.17
    gatsby-plugin-nprogress: ^2.3.13 => 2.3.13
    gatsby-plugin-offline: ^3.2.31 => 3.2.31
    gatsby-plugin-react-helmet: ^3.3.14 => 3.3.14
    gatsby-plugin-robots-txt: ^1.5.3 => 1.5.3
    gatsby-plugin-sass: ^2.3.16 => 2.3.16
    gatsby-plugin-sharp: ^2.6.40 => 2.6.40
    gatsby-plugin-sitemap: ^2.4.15 => 2.4.15
    gatsby-plugin-smoothscroll: ^1.2.0 => 1.2.0
    gatsby-remark-embedder: ^3.0.0 => 3.0.0
    gatsby-remark-images: ^3.3.33 => 3.3.33
    gatsby-remark-images-contentful: ^2.3.19 => 2.3.19
    gatsby-remark-relative-images: ^2.0.2 => 2.0.2
    gatsby-source-contentful: ^2.3.51 => 2.3.51
    gatsby-source-filesystem: ^2.3.34 => 2.3.34
    gatsby-transformer-remark: ^2.8.38 => 2.8.38
    gatsby-transformer-sharp: ^2.5.17 => 2.5.17
  npmGlobalPackages:
    gatsby-cli: 2.12.101
``

Answer 1

@Vladar responded with a FIX!

https://github.com/gatsbyjs/gatsby/issues/27385#issuecomment-707020486