gatsby-node.js

/**
 * Implement Gatsby's Node APIs in this file.
 *
 * See: https://www.gatsbyjs.com/docs/node-apis/
 */

// You can delete this file if you're not using it
//
const path = require("path")
const { createFilePath } = require("gatsby-source-filesystem")

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

  if (node.internal.type === "Mdx") {
    const value = createFilePath({ node, getNode })
    createNodeField({
      name: "slug",
      node,
      value,
    })
  }
}

exports.createPages = async ({ graphql, actions, reporter }) => {
  const { createPage } = actions

  const result = await graphql(`
    query {
      allMdx {
        edges {
          node {
            id
            fields {
              slug
            }
          }
        }
      }
    }
  `)

  if (result.errors) {
    reporter.panicOnBuild('🚨  ERROR: Loading "createPages" query')
  }

  const posts = result.data.allMdx.edges

  posts.forEach(({ node }, index) => {
    console.log(node.fields.slug)
    createPage({
      path: node.fields.slug,
      component: path.resolve("./src/components/layout.js"),
      context: { id: node.id },
    })
  })
}