gatsby-node.js

const path = require('path');

// create pages dynamically
exports.createPages = async ({ graphql, actions }) => {
  const { createPage } = actions;
  // Query for posts and libros separately
  const result = await graphql(`
    {
      allMdx {
        nodes {
          frontmatter {
            slug
            author
            authorContact
          }
        }
      }
      allLibros: allMdx(filter: { frontmatter: { type: { eq: "libro" } } }) {
        nodes {
          frontmatter {
            slug
            title
            author
          }
        }
      }
      concepts: allMdx {
        totalCount
        distinct(field: frontmatter___concepts)
      }
    }
  `);

  // Create pages for each post
  result.data.allMdx.nodes.forEach(({ frontmatter: { slug } }) => {
    createPage({
      path: `/posts/${slug}`,
      component: path.resolve(`src/templates/PostLayout.js`),
      context: {
        slug,
      },
    });
  });

  // Create pages for each book
  result.data.allLibros.nodes.forEach(({ frontmatter: { slug } }) => {
    createPage({
      path: `/libro/${slug}`,
      component: path.resolve(`src/templates/BookLayout.js`),
      context: {
        slug,
      },
    });
  });

  // Create pages for each author
  result.data.allMdx.nodes.forEach(({ frontmatter: { author, authorContact } }) => {
    createPage({
      path: `/autores/${author}`,
      component: path.resolve(`src/templates/AuthorLayout.js`),
      context: {
        author,
        authorContact,
      },
    });
  });

  // Create pages for each concept
  result.data.concepts.distinct.forEach((concept) => {
    createPage({
      path: `/concepts/${concept}`,
      component: path.resolve(`src/templates/ConceptLayout.js`),
      context: {
        concept,
      },
    });
  });
};