gatsby-node.ts

import type { GatsbyNode } from "gatsby";

const path = require("path");

export const createPages: GatsbyNode["createPages"] = async ({
  graphql,
  actions,
  reporter,
}) => {
  const { createPage } = actions;

  const result = await graphql<any>(`
    query {
      allMdx {
        nodes {
          body
          excerpt(pruneLength: 150)
          frontmatter {
            slug
          }
          id
          internal {
            contentFilePath
          }
        }
      }
    }
  `);

  if (result.errors) {
    reporter.panicOnBuild("Failed to create posts: ", result.errors);
  }

  const posts = result.data.allMdx.nodes;
  const postTemplate = path.resolve(`./src/templates/post.tsx`);

  posts.forEach((node: any) => {
    createPage({
      path: `/posts${node.frontmatter.slug}`,
      component: `${postTemplate}?__contentFilePath=${node.internal.contentFilePath}`,
      context: { id: node.id },
    });
  });
};