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Custom sync handlers for Sanity Connect

A custom sync handler allows you to provide an endpoint which receives updates from Shopify and passes data into your content lake. Typically, this will be a serverless function where you can reshape the data from Shopify and apply business logic before it is passed to your content lake.

When to use a custom sync handler

There are a number of scenarios where you may choose to implement a custom sync handler - common examples include:

  • Where you need to apply additional logic to the data - for example, querying additional APIs to retrieve more data (e.g. the Shopify API to get additional metafields)
  • You may want to reduce your document usage on Sanity by only syncing selected products, or syncing variants as an object on product documents rather than variant documents.
  • Where you want to amend the default manner in which Sanity Connect handles a product being deleted on Shopify - by setting isDeleted to true - to fully delete the document from your content lake.

How custom sync handlers work

When enabled, the custom sync handler will send a payload on every update from Shopify as a POST request. You can write your custom business logic in your endpoint and update your content lake accordingly in the function, or respond with a set of documents which Sanity Connect will update for you.

Sanity Connect expects a response header with content-type: application/json and will regard a 200 status code as a success. Any other status code will be considered a failure.

You can find the shape of the payload your handler will receive in our Sanity Connect reference.

Gotcha

The request has a 10s timeout and your handler needs to reply before that. Any failed requests will be retried up to 10 times.

If your handler needs more time to complete updates (for example if it calls a third party API), a common pattern would be to store the payload in a queue for background processing, and respond 200 OK immediately to acknowledge receipt of the payload.

Gotcha

This operation will in batched when manually syncing, especially when dealing with larger catalogs.

Gotcha

Changes in product inventory (through sales) will also trigger updates to your custom handler.

Make sure to tailor your custom handler to account for how our API CDN invalidates cache on writes to non-draft documents, especially if operating on a high traffic stores with fast moving content.

Example custom sync handler function

Below is an example of a barebones custom function that will:

  • Create/update/delete products (including drafts) in the Content Lake on Shopify product operations
  • Only deal with products (variants are included as objects within products)
  • Manual sync will create and update products on your dataset, but will not delete products that have since been removed.

For a more complete example, refer to this gist.

import {createClient} from "@sanity/client";

// Document type for all incoming synced Shopify products
const SHOPIFY_PRODUCT_DOCUMENT_TYPE = "shopify.product";

// Prefix added to all Sanity product document ids
const SHOPIFY_PRODUCT_DOCUMENT_ID_PREFIX = "product-";

// Enter your Sanity studio details here.
// You will also need to provide an API token with write access in order for this
// handler to be able to create documents on your behalf.
// Read more on auth, tokens and securing them: https://www.sanity.io/docs/http-auth
const sanityClient = createClient({
  apiVersion: "2021-10-21",
  dataset: process.env.SANITY_DATASET,
  projectId: process.env.SANITY_PROJECT_ID,
  token: process.env.SANITY_ADMIN_AUTH_TOKEN,
  useCdn: false,
});

/**
 * Sanity Connect sends POST requests and expects both:
 * - a 200 status code
 * - a response header with `content-type: application/json`
 * 
 * Remember that this may be run in batches when manually syncing.
 */
export default async function handler(req, res) {
  // Next.js will automatically parse `req.body` with requests of `content-type: application/json`,
  // so manually parsing with `JSON.parse` is unnecessary.
  const { body, method } = req;

  // Ignore non-POST requests
  if (method !== "POST") {
    return res.status(405).json({ error: "Method not allowed" });
  }

  try {
    const transaction = sanityClient.transaction();
    switch (body.action) {
      case "create":
      case "update":
      case "sync":
        await createOrUpdateProducts(transaction, body.products);
        break;
      case "delete":
        const documentIds = body.productIds.map((id) =>
          getDocumentProductId(id)
        );
        await deleteProducts(transaction, documentIds);
        break;
    }
    await transaction.commit();
  } catch (err) {
    console.error("Transaction failed: ", err.message);
  }

  res.status(200).json({ message: "OK" });
}

/**
 * Creates (or updates if already existing) Sanity documents of type `shopify.product`.
 * Patches existing drafts too, if present.
 *
 * All products will be created with a deterministic _id in the format `product-${SHOPIFY_ID}`
 */
async function createOrUpdateProducts(transaction, products) {
  // Extract draft document IDs from current update
  const draftDocumentIds = products.map((product) => {
    const productId = extractIdFromGid(product.id);
    return `drafts.${getDocumentProductId(productId)}`;
  });

  // Determine if drafts exist for any updated products
  const existingDrafts = await sanityClient.fetch(`*[_id in $ids]._id`, {
    ids: draftDocumentIds,
  });

  products.forEach((product) => {
    // Build Sanity product document
    const document = buildProductDocument(product);
    const draftId = `drafts.${document._id}`;

    // Create (or update) existing published document
    transaction
      .createIfNotExists(document)
      .patch(document._id, (patch) => patch.set(document));

    // Check if this product has a corresponding draft and if so, update that too.
    if (existingDrafts.includes(draftId)) {
      transaction.patch(draftId, (patch) =>
        patch.set({
          ...document,
          _id: draftId,
        })
      );
    }
  });
}

/**
 * Delete corresponding Sanity documents of type `shopify.product`.
 * Published and draft documents will be deleted.
 */
async function deleteProducts(transaction, documentIds) {
  documentIds.forEach((id) => {
    transaction.delete(id).delete(`drafts.${id}`);
  });
}

/**
 * Build Sanity document from product payload
 */
function buildProductDocument(product) {
  const {
    featuredImage,
    id,
    options,
    productType,
    priceRange,
    status,
    title,
    variants,
  } = product;
  const productId = extractIdFromGid(id);
  return {
    _id: getDocumentProductId(productId),
    _type: SHOPIFY_PRODUCT_DOCUMENT_TYPE,
    image: featuredImage?.src,
    options: options?.map((option, index) => ({
      _key: String(index),
      name: option.name,
      position: option.position,
      values: option.values,
    })),
    priceRange,
    productType,
    status,
    title,
    variants: variants?.map((variant, index) => {
      const variantId = extractIdFromGid(variant.id);
      return {
        _key: String(index),
        compareAtPrice: Number(variant.compareAtPrice || 0),
        id: variantId,
        inStock: !!variant.inventoryManagement
          ? variant.inventoryPolicy === "continue" ||
            variant.inventoryQuantity > 0
          : true,
        inventoryManagement: variant.inventoryManagement,
        inventoryPolicy: variant.inventoryPolicy,
        option1: variant?.selectedOptions?.[0]?.value,
        option2: variant?.selectedOptions?.[1]?.value,
        option3: variant?.selectedOptions?.[2]?.value,
        price: Number(variant.price || 0),
        sku: variant.sku,
        title: variant.title,
      };
    }),
  };
}

/**
 * Extract ID from Shopify GID string (all values after the last slash)
 * e.g. gid://shopify/Product/12345 => 12345
 */
function extractIdFromGid(gid) {
  return gid?.match(/[^\/]+$/i)[0];
}

/**
 * Map Shopify product ID number to a corresponding Sanity document ID string
 * e.g. 12345 => product-12345
 */
function getDocumentProductId(productId) {
  return `${SHOPIFY_PRODUCT_DOCUMENT_ID_PREFIX}${productId}`;
}

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