gatsby-node.ts

import path from 'path';
import { GatsbyNode } from 'gatsby';
import { createFilePath } from 'gatsby-source-filesystem';

export const createPages: GatsbyNode['createPages'] = async ({
  graphql,
  actions,
}) => {
  const { createPage } = actions;
  const result = await graphql(`
    query GetPages {
      allMdx(sort: { frontmatter: { date: DESC } }, limit: 1000) {
        nodes {
          id
          frontmatter {
            title
            date(formatString: "YYYY.MM.DD")
            emoji
            category
            slug
          }
          internal {
            contentFilePath
          }
        }
      }
    }
  `);
  if (result.errors) {
    throw result.errors;
  }
  const nodes = (result.data as any).allMdx.nodes;

  let categories: Set<string> = new Set();

  nodes.forEach((node) => {
    if (node.frontmatter.category) {
      categories.add(node.frontmatter.category); // Set에 추가
    }
  });
  categories = new Set(categories);
  categories.forEach((category) => {
    createPage({
      path: `/category/${category.replace(/\s/, '-')}/`,
      component: path.resolve('src/templates/categories.tsx'),
      context: {
        category,
      },
    });
  });
};

export const onCreateNode: GatsbyNode['onCreateNode'] = ({
  node,
  actions,
  getNode,
}) => {
  const { createNodeField } = actions;

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