gatsby-node.js

const _ = require("lodash");
const Promise = require("bluebird");
const path = require("path");
const select = require(`unist-util-select`);
const fs = require(`fs-extra`);

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

  return new Promise((resolve, reject) => {
    const pages = [];
    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
            }
          });
        });
      })
    );
  });
};