Dgraph Lambdas are a great asset and feature to have. They are not though what they sometime get made out to be. So while they add value, they do have limitations.

First some contextual references and then I get into the limitations.

The Hook Request

Custom hook for mutation

The RFC

Implement custom JS resolvers in GraphQL

The Need to Pass Variables into Lambdas

Pass Client Variables through Directive to Lambda

RFC: Webhook Lambda on add/update/delete mutations

Webhook (Lambda) on add/update/delete mutations

The Need for Pre-Mutation Lambdas

Feature Request: Access Deleted or Changed Data in Lambda Webhook

The Need for data in Webhooks

Add Node Predicates to Lambda Update/Delete Webhooks

Limitations