gatsby-node.js

const path = require('path')

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

  if (node.internal.type === 'Mdx') {
    const parent = getNode(node.parent)

    if (parent.internal.type === 'File') {
      createNodeField({
        name: 'sourceName',
        node,
        value: parent.sourceInstanceName,
      })
    }
  }
}

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

  const blogPosts = await graphql(`
    {
      allMdx(
        filter: { fields: { sourceName: { eq: "blog" } } }
        sort: { fields: frontmatter___date, order: DESC }
        limit: 1000
      ) {
        nodes {
          slug
        }
      }
    }
  `)

  if (blogPosts.errors) {
    reporter.panicOnBuild(`Error while running GraphQL query.`)
    return
  }

  const posts = blogPosts.data.allMdx.nodes
  const postsPerPage = 6
  const numPages = Math.ceil(posts.length / postsPerPage)
  Array.from({ length: numPages }).forEach((_, i) => {
    createPage({
      path: i === 0 ? `/blog` : `/blog/${i + 1}`,
      component: path.resolve('./src/templates/blog-list-template.tsx'),
      context: {
        limit: postsPerPage,
        skip: i * postsPerPage,
        numPages,
        currentPage: i + 1,
      },
    })
  })
}