gatsby-node.js

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

  const path = require("path");

  exports.createPages = ({ boundActionCreators, graphql }) => {
    const { createPage } = boundActionCreators;
    const blogPostTemplate = path.resolve("src/templates/post.js");

    return graphql(`
      {
        allMarkdownRemark(sort: { order: DESC, fields: [frontmatter___date] }, limit: 1000) {
          edges {
            node {
              excerpt(pruneLength: 250)
              html
              id
              frontmatter {
                date
                path
                title
              }
            }
          }
        }
      }
    `).then(result => {
      if (result.errors) {
        return Promise.reject(result.errors);
      }
      result.data.allMarkdownRemark.edges.forEach(({ node }) => {
        createPage({
          path: node.frontmatter.path,
          component: blogPostTemplate,
          context: {}
        });
      });
    });
  };