内容层：深度解析

---
import type { GetStaticPaths } from 'astro';
import { getCollection } from 'astro:content';

export const getStaticPaths: GetStaticPaths = async () => {
  const collection = await getCollection('countries');
  if (!collection) return [];
  return collection.map((country) => ({
    params: {
      id: country.id,
    },
    props: {
      country,
    },
  }));
};

const { country } = Astro.props;
---

<h1>{craft.data.name}</h1>
<p>Capital: {craft.data.capital}</p>

export function feedLoader({ url }: FeedLoaderOptions): Loader {
  const feedUrl = new URL(url);
  // Return a loader object
  return {
    // The name of the loader. This is used in logs and error messages.
    name: 'feed-loader',
    // The load method is called to load data
    load: async ({ store, logger, meta }) => {
      // Check if there's a last-modified time already stored
      const lastModified = meta.get('last-modified');

      // If so, make a conditional request for the feed
      const headers = lastModified ? { 'If-Modified-Since': lastModified } : {};

      const res = await fetch(feedUrl, { headers });

      // If the feed hasn't changed, you do not need to update the store
      if (res.status === 304) {
        logger.info('Feed not modified, skipping');
        return;
      }
      if (!res.ok || !res.body) {
        throw new Error(`Failed to fetch feed: ${res.statusText}`);
      }

      // Store the last-modified header in the meta store so we can
      // send it with the next request
      meta.set('last-modified', res.headers.get('last-modified'));

      // ... now store the data
    },
  };
}

export function feedLoader({ url }: FeedLoaderOptions): Loader {
  const feedUrl = new URL(url);
  // Return a loader object
  return {
    // The name of the loader. This is used in logs and error messages.
    name: 'feed-loader',
    // The load method is called to load data
    load: async ({ store, logger, meta }) => {
      // Check if there's a last-modified time already stored
      const lastModified = meta.get('last-modified');

      // If so, make a conditional request for the feed
      const headers = lastModified ? { 'If-Modified-Since': lastModified } : {};

      const res = await fetch(feedUrl, { headers });

      // If the feed hasn't changed, you do not need to update the store
      if (res.status === 304) {
        logger.info('Feed not modified, skipping');
        return;
      }
      if (!res.ok || !res.body) {
        throw new Error(`Failed to fetch feed: ${res.statusText}`);
      }

      // Store the last-modified header in the meta store so we can
      // send it with the next request
      meta.set('last-modified', res.headers.get('last-modified'));

      const feed = parseFeed(res.body);

      // If the loader doesn't handle incremental updates, clear the store before inserting new entries
      // In some cases the API might send a stream of updates, in which case you would not want to clear the store
      // and instead add, delete, or update entries as needed.
      store.clear();

      for (const item of feed.items) {
        // The parseData helper uses the schema to validate and transform data
        const data = await parseData({
          id: item.guid,
          data: item,
        });

        // The generateDigest helper lets you generate a digest based on the content. This is an optional
        // optimization. When inserting data into the store, if the digest is provided then the store will
        // check if the content has changed before updating the entry. This will avoid triggering a rebuild
        // in development if the content has not changed.
        const digest = generateDigest(data);

        store.set({
          id,
          data,
          // If the data source provides HTML, it can be set in the `rendered` property
          // This will allow users to use the `<Content />` component in their pages to render the HTML.
          rendered: {
            html: data.description ?? '',
          },
          digest,
        });
      }
    },
  };
}