Sanity Client: Migrate Document Type

migrate-document-type.js

import client from 'part:@sanity/base/client';

// Run this script with: `sanity exec --with-user-token scripts/migrate-document-type.js`

const OLD_TYPE = 'siteTool';
const NEW_TYPE = 'site.tool';

const fetchDocuments = () =>
	client.fetch(
		`*[_type == $oldType][0...10] {..., "incomingReferences": *[references(^._id)]{...}}`,
		{ oldType: OLD_TYPE }
	);

const buildMutations = (docs) => {
	const mutations = [];

	docs.forEach((doc) => {
		console.log('movie', doc._id);
		// Updating an document _type field isn't allowed, we have to create a new and delete the old
		const newDocId = `${doc._id}-migrated`;
		const newDocument = { ...doc, ...{ _id: newDocId, _type: NEW_TYPE } };
		delete newDocument.incomingReferences;
		delete newDocument._rev;

		mutations.push({ create: newDocument });

		// Patch each of the incoming references
		doc.incomingReferences.forEach((referencingDocument) => {
			console.log('ref', referencingDocument._id);
			// ⚠️ We're assuming the field is named the same as the type!
			// There might be another structure involved, perhaps an array, that needs patching
			const updatedReference = {
				[NEW_TYPE]: {
					_ref: newDocId,
					_type: 'reference'
				}
			};
			mutations.push({
				id: referencingDocument._id,
				patch: {
					set: updatedReference,
					unset: [OLD_TYPE],
					ifRevisionID: referencingDocument._rev
				}
			});
		});

		// Apply the delete mutation after references have been changed
		mutations.push({ delete: doc._id });
	});
	return mutations.filter(Boolean);
};

const createTransaction = (mutations) => {
	return mutations.reduce((tx, mutation) => {
		if (mutation.patch) {
			return tx.patch(mutation.id, mutation.patch);
		}
		if (mutation.delete) {
			return tx.delete(mutation.delete);
		}
		if (mutation.create) {
			return tx.createIfNotExists(mutation.create);
		}
	}, client.transaction());
};

const migrateNextBatch = async () => {
	const documents = await fetchDocuments();
	if (documents.length === 0) {
		console.log('No more documents to migrate!');
		return null;
	}
	const mutations = buildMutations(documents);
	const transaction = createTransaction(mutations);
	await transaction.commit();
	return migrateNextBatch();
};

migrateNextBatch().catch((err) => {
	console.error(JSON.stringify(err, null, 2));
	process.exit(1);
});