Automating cross-site sync

import Butter from 'buttercms';

// Source site (read token) and destination site (write token)
const sourceButter = Butter('source-site-read-token');
const DEST_WRITE_TOKEN = 'dest-site-write-token';

// The JS SDK's Content resource is read-only, so writes to the destination
// site go directly to the Write API.
async function createCollectionItem(collectionSlug, fields) {
  const res = await fetch('https://api.buttercms.com/v2/content/', {
    method: 'POST',
    headers: {
      'Authorization': `Token ${DEST_WRITE_TOKEN}`,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ key: collectionSlug, fields: [fields] })
  });
  if (!res.ok) {
    throw new Error(`Write API ${res.status}: ${await res.text()}`);
  }
}

async function syncCollection(collectionSlug) {
  // Fetch from source
  const { data } = await sourceButter.content.retrieve(collectionSlug);
  const items = data.data[collectionSlug];

  // Push to destination. Read responses include a `meta` object per item,
  // which the Write API rejects as an unknown field.
  for (const { meta, ...fields } of items) {
    await createCollectionItem(collectionSlug, fields);
  }

  console.log(`Synced ${items.length} items to ${collectionSlug}`);
}

// Sync authors collection
syncCollection('authors');

async function syncLocalizedCollection(collectionSlug, locales) {
  const fieldsByItemId = new Map();

  for (const locale of locales) {
    const { data } = await sourceButter.content.retrieve(collectionSlug, { locale });
    for (const { meta, ...fields } of data.data[collectionSlug]) {
      const item = fieldsByItemId.get(meta.id) ?? {};
      item[locale] = fields;
      fieldsByItemId.set(meta.id, item);
    }
  }

  // Each item is posted as fields: [{ en: {...}, es: {...} }]
  for (const fieldsByLocale of fieldsByItemId.values()) {
    await createCollectionItem(collectionSlug, fieldsByLocale);
  }

  console.log(`Synced ${fieldsByItemId.size} localized items to ${collectionSlug}`);
}

syncLocalizedCollection('authors', ['en', 'es']);

// AWS Lambda / Vercel Serverless Function
import Butter from 'buttercms';

// The JS SDK's Page resource is read-only (retrieve/list/search), so creating
// pages on the destination site goes directly to the Write API.
export async function handler(event) {
  const sourceButter = Butter(process.env.SOURCE_READ_TOKEN);
  // Use a page type key; '*' lists single pages, which have no page type
  // and can't be created through the Write API
  const pageType = 'landing-page';

  // Fetch recently updated content
  const { data } = await sourceButter.page.list(pageType, {
    page_size: 100,
    order: '-updated'
  });

  // Sync to destination
  for (const page of data.data) {
    const res = await fetch('https://api.buttercms.com/v2/pages/', {
      method: 'POST',
      headers: {
        'Authorization': `Token ${process.env.DEST_WRITE_TOKEN}`,
        'Content-Type': 'application/json'
      },
      body: JSON.stringify({
        'page-type': pageType,
        title: page.name,
        slug: page.slug,
        status: 'draft',
        fields: page.fields
      })
    });
    if (!res.ok) {
      throw new Error(`Write API ${res.status} for ${page.slug}: ${await res.text()}`);
    }
  }

  return { statusCode: 200, body: 'Sync complete' };
}