gatsby-node.js

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

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


exports.createPages = async ({ actions, graphql, reporter }) => {
  const { createPage } = actions
  const blogPostTemplate = path.resolve(`src/templates/blogTemplate.js`)
  const result = await graphql(`
    {
      allMarkdownRemark(
        sort: { order: DESC, fields: [frontmatter___date] }
        limit: 1000
        filter: {fields: {contentType: {eq: "blog"}}}
      ) {
        edges {
          node {
            frontmatter {
              path
            }
          }
        }
      }
    }
  `)
  // Handle errors
  if (result.errors) {
    reporter.panicOnBuild(`Error while running GraphQL query.`)    
    return
  }
  result.data.allMarkdownRemark.edges.forEach(({ node }) => {
    createPage({
      path: node.frontmatter.path,
      component: blogPostTemplate,
      context: {}, // additional data can be passed via context
    })
  })
}

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

  // convert frontmatter images
  // fmImagesToRelative(node)

  // Create smart slugs
  // https://github.com/Vagr9K/gatsby-advanced-starter/blob/master/gatsby-node.js
  let slug
  if (node.internal.type === 'MarkdownRemark') {

    const fileNode = getNode(node.parent)
    const parsedFilePath = path.parse(fileNode.relativePath)
    const value = createFilePath({node, getNode})

    createNodeField({
      name: `slug`,
      node,
      value,
    })

    // Add contentType to node.fields
    createNodeField({
      node,
      name: 'contentType',
      value: parsedFilePath.dir
    })
  }
}