gatsby-node.js

const _ = require("lodash")
const Promise = require('bluebird')
const path = require('path')

exports.createPages = ({ graphql, boundActionCreators }) => {
  const { createPage } = boundActionCreators

  return new Promise((resolve, reject) => {
    const blogPost = path.resolve("./src/templates/blog-post.js")
    resolve(
      graphql(
        `
          {
            allMarkdownRemark(limit: 1000) {
              edges {
                node {
                  frontmatter {
                    path
                  }
                }
              }
            }
          }
        `
      ).then(result => {
        if (result.errors) {
          console.log(result.errors)
          reject(result.errors)
        }

        // Create blog posts pages.
        _.each(result.data.allMarkdownRemark.edges, edge => {
          createPage({
            path: edge.node.frontmatter.path,
            component: blogPost,
            context: {
              path: edge.node.frontmatter.path,
            },
          })
        })
      })
    )
  })
}