Connecting two gatsby nodes

Question

So, I\'m using the gatsby-mdx plugin to create a site from MDX files. I want to create an association between the SitePage object and the Mdx object so that I can do one gra

Answer 1

So I finally found a better solution (than my previous attempt, which involves pumping mdx node into page’s context).

Gatsby has a undocumented method to link nodes to one another:

Yes, you can can use createNodeField with the not-yet-documented ___NODE syntax to create links between nodes.

So, the steps are like this:

• In createPage, store the id of the Mdx node to SitePage node.
• In onCreateNode, if node is SitePage, use createNodeField with the Mdx___NODE as field name and Mdx node's id as value.

My gatsby-node.js:

const path = require("path")
const { createFilePath } = require("gatsby-source-filesystem")

exports.onCreateNode = ({ node, actions, getNode }) => {
  const { createNodeField } = actions

  if (node.internal.type === "SitePage" && node.context && node.context.id) {

    createNodeField({
      name: "Mdx___NODE",
      value: node.context.id,
      node,
    })
  }

  if (node.internal.type === "Mdx") {
    const value = createFilePath({ node, getNode })
    createNodeField({
      // 1) this is the name of the field you are adding,
      name: "slug",
      // 2) this node refers to each individual MDX
      node,
      value: `/blog${value}`
    })
  }
}


exports.createPages = async ({ graphql, actions }) => {
  const { createPage } = actions;
  const { data, errors } = await graphql(`
    {
      allMdx {
        edges {
          node {
            id
            fields {
              slug
            }
          }
        }
      }
    }
  `)

  if (errors) throw errors
  data.allMdx.edges.forEach(({ node }) => {
    createPage({
      path: node.fields.slug,
      component: path.resolve(`./src/components/posts-page-layout.js`),
      context: { id: node.id }
    });
  });
};

Result:

Hope it helps!