Populate MDX node from frontmatter MusicBrainz IDs

gatsby-node.js

const {
  default_musicBrainzReleaseFields,
  queryMusicBrainzRelease
} = require("./src/fragments/musicbrainz");
exports.onCreateNode = async ({
  node,
  actions,
  getNode,
  createNodeId,
  store,
  cache
}) => {
  const { createNodeField, createNode } = actions;
  switch (node.internal.type) {
    case `JavascriptFrontmatter`:
    case `Mdx`:
      createNodeField({
        name: `slug`,
        node,
        value: createFilePath({ node, getNode })
      });
      const fileNode = getNode(node.parent);
      createNodeField({
        name: "sourceInstanceName",
        node,
        value: fileNode.sourceInstanceName
      });
      let release_fields = [];
      let covers = [];
      if (fileNode.sourceInstanceName == `playlist`) {
        // Retrieve MusicBrainz Ids from frontmatter post
        const mbids = Array.isArray(node.frontmatter.mbid)
          ? node.frontmatter.mbid
          : [node.frontmatter.mbid];
        // Query MusicBrainz API to source album information for each ID
        await mbids.forEach(async mbid => {
          const { result } = await wrapper(queryMusicBrainzRelease(mbid));
          // Download covers and create dedicated node
          const coverFileNode = await createRemoteFileNode({
            url: result.lookup.release.coverArtArchive.front,
            store,
            cache,
            createNode,
            createNodeId
          });
          // Add results to a field of Mdx node + a link to cover file
          covers.push(coverFileNode.id);
          release_fields.push({
            ...default_musicBrainzReleaseFields,
            ...result.lookup.release,
            cover___NODE: coverFileNode.id
          });
        });
      }
      // Add everything into a node field named graphbrainz__release
      createNodeField({
        name: "graphbrainz__release",
        node,
        value: release_fields
      });
  }
};