next.js/examples/cms-cosmic/lib/api.tsx

import Cosmic from "cosmicjs";
import { PostType } from "interfaces";
import ErrorPage from "next/error";

const BUCKET_SLUG = process.env.COSMIC_BUCKET_SLUG;
const READ_KEY = process.env.COSMIC_READ_KEY;

const bucket = Cosmic().bucket({
  slug: BUCKET_SLUG,
  read_key: READ_KEY,
});

export const getPreviewPostBySlug = async (slug: string) => {
  const params = {
    query: {
      slug,
      type: "posts",
    },
    props: "slug",
    status: "any",
  };

  try {
    const data = await bucket.getObjects(params);
    return data.objects[0];
  } catch (err) {
    // Don't throw if an slug doesn't exist
    return <ErrorPage statusCode={err.status} />;
  }
};

export const getAllPostsWithSlug = async () => {
  const params = {
    query: {
      type: "posts",
    },
    props: "slug",
  };
  const data = await bucket.getObjects(params);
  return data.objects;
};

export const getAllPostsForHome = async (
  preview: boolean,
): Promise<PostType[]> => {
  const params = {
    query: {
      type: "posts",
    },
    props: "title,slug,metadata,created_at",
    sort: "-created_at",
    ...(preview && { status: "any" }),
  };
  const data = await bucket.getObjects(params);
  return data.objects;
};

export const getPostAndMorePosts = async (
  slug: string,
  preview: boolean,
): Promise<{
  post: PostType;
  morePosts: PostType[];
}> => {
  const singleObjectParams = {
    query: {
      slug,
      type: "posts",
    },
    props: "slug,title,metadata,created_at",
    ...(preview && { status: "any" }),
  };
  const moreObjectParams = {
    query: {
      type: "posts",
    },
    limit: 3,
    props: "title,slug,metadata,created_at",
    ...(preview && { status: "any" }),
  };
  let object;
  try {
    const data = await bucket.getObjects(singleObjectParams);
    object = data.objects[0];
  } catch (err) {
    throw err;
  }
  const moreObjects = await bucket.getObjects(moreObjectParams);
  const morePosts = moreObjects.objects
    ?.filter(({ slug: object_slug }) => object_slug !== slug)
    .slice(0, 2);

  return {
    post: object,
    morePosts,
  };
};