gatsby-node.js

const path = require("path");
const { paginate } = require("gatsby-awesome-pagination");
const _ = require("lodash");

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

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

  const query = await graphql(`
    {
      site {
        siteMetadata {
          postsPerPage
        }
      }

      posts: allMdx(
        sort: { order: DESC, fields: frontmatter___date }
        filter: { fileAbsolutePath: { regex: "/blog/" } }
      ) {
        nodes {
          slug
        }
      }

      tags: allMdx(sort: { order: DESC, fields: frontmatter___tags }) {
        group(field: frontmatter___tags) {
          tag: fieldValue
        }
      }
    }
  `);

  // Check for any errors
  if (query.errors) {
    throw new Error(query.errors);
  }

  const posts = query.data.posts.nodes;
  const tags = query.data.tags.group;

  const blogIndexTemplate = path.resolve(`src/templates/blog.js`);
  const tagsTemplate = path.resolve(`src/templates/tag.js`);

  // Create tag pages
  tags.forEach((tag) => {
    createPage({
      path: `/tags/${_.kebabCase(tag.tag)}`,
      component: tagsTemplate,
      context: {
        tag: tag.tag,
      },
    });
  });

  // Create your paginated pages
  paginate({
    createPage, // The Gatsby `createPage` function
    items: posts, // An array of objects
    itemsPerPage: query.data.site.siteMetadata.postsPerPage,
    pathPrefix: "/blog", // Creates pages like `/blog`, `/blog/2`, etc
    component: blogIndexTemplate,
  });
};

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

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

// Define schema for Hello Bar & frontmatter
exports.createSchemaCustomization = ({ actions }) => {
  const { createTypes } = actions;
  const typeDefs = `
  type HelloBarYaml implements Node {
    display: Boolean
    title: String
    end_date: Date
    background_color: String
    link_text: String
    link_url: String
  }
  `;
  createTypes(typeDefs);
};