rickvanlieshout.com/internal/gatsby/queries/categories-query.ts

import { CreatePagesArgs } from "gatsby";

interface CategoriesQueryResult {
  allMarkdownRemark: {
    group: Array<{
      fieldValue: string;
      totalCount: number;
    }>;
  };
}

const categoriesQuery = async (graphql: CreatePagesArgs["graphql"]) => {
  const result = await graphql<CategoriesQueryResult>(`
    {
      allMarkdownRemark(
        filter: { frontmatter: { template: { eq: "post" }, draft: { ne: true } } }
        sort: { frontmatter: { date: DESC } }
      ) {
        group(field: { frontmatter: { category: SELECT } }) {
          fieldValue
          totalCount
        }
      }
    }
  `);

  return result?.data?.allMarkdownRemark?.group ?? [];
};

export default categoriesQuery;