gatsby-node.js

const path = require(`path`)
const { createFilePath } = require(`gatsby-source-filesystem`)

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

  const blogPost = path.resolve(`./src/templates/blog-post.js`)
  return graphql(
    `
      {
        allMarkdownRemark(sort: {frontmatter: {date: DESC}}, limit: 1000) {
          edges {
            node {
              fields {
                slug
              }
              frontmatter {
                title
              }
            }
          }
        }
      }
    `
  ).then(result => {
    if (result.errors) {
      throw result.errors
    }

    // Create blog posts pages.
    const posts = result.data.allMarkdownRemark.edges

    posts.forEach((post, index) => {
      const previous = index === posts.length - 1 ? null : posts[index + 1].node
      const next = index === 0 ? null : posts[index - 1].node

      createPage({
        path: post.node.fields.slug,
        component: blogPost,
        context: {
          slug: post.node.fields.slug,
          previous,
          next,
        },
      })
    })

    // Create blog post list pages
    const postsPerPage = 5;
    const numPages = Math.ceil(posts.length / postsPerPage);

    Array.from({ length: numPages }).forEach((_, i) => {
      createPage({
        path: i === 0 ? `/` : `/${i + 1}`,
        component: path.resolve('./src/templates/blog-list.js'),
        context: {
          limit: postsPerPage,
          skip: i * postsPerPage,
          numPages,
          currentPage: i + 1
        },
      });
    });
  })
}

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

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

var copydir = require('copy-dir');
const fs = require('fs');

exports.onPostBuild = () => {

  const source = `${__dirname}/public`;
  const destination = '../_site/blog';
  
  if (!fs.existsSync(destination)) {
    fs.mkdirSync(destination, { recursive: true });
  }
  console.log(`Copying Files from ${source} to ${destination}...`);
  copydir.sync(source, destination);
  console.log(`Finished Copying Files to ${destination}.`);

}