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28 Aug 2023

Apibara Changelog #2

Entity mode for the MongoDB integration

This week, we are launching a new entity mode for the MongoDB integration. This new mode gives you even more power by enabling you to insert and update existing entities that you previously inserted in Mongo.

Before you can try out entity mode, you need to update the MongoDB integration:

apibara plugins install sink-mongo

To enable entity mode, set the entityMode option to true. You must then change your transform function to return a list of entity operations. These operations are JSON objects that contain an entity property that specifies which entities need update and an update property with a Mongo update operation or Mongo pipeline on that entity.

For example, the following update operation updates the owner of an NFT token and, at the same time, increases the transaction count on the same token.

export default function transform({ header, events }: Block) {
const tokenIdCount = new Map<string, number>();
const tokenIdToOwner = new Map<string, string>();
for (const { event } of events) {
const dest = event.data[1];
const tokenId = uint256.uint256ToBN({
low: event.data[2],
high: event.data[3],
tokenIdToOwner.set(tokenId.toString(), dest);
(tokenIdCount.get(tokenId.toString()) ?? 0) + 1,
return [...tokenIdToOwner.entries()].map(([tokenId, owner]) => ({
entity: {
update: {
"$set": {
updateAt: header?.timestamp,
updateAtBlock: header?.blockNumber,
"$inc": {
transferCount: tokenIdCount.get(tokenId) ?? 0,

You can read more about entity mode, including details about its implementation, in our documentation. Looking forward to seeing what you're going to build with it!

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