I am looking for a low-code system where I could easily add code for custom business logic (on the backend) when needed. Most of these systems seem well-suited to reading data, but don't seem suitable to writing it for non-trivial use cases.

pocketbase.io has some hooks for when data is saved, but currently only supports SQLite as a backend.

Directus seems to have some custom validation ability.

All these systems don't seem to have a way to add custom validation logic:

https://appwrite.io/docs/getting-started-for-web https://github.com/appsmithorg/appsmith https://docs.openblocks.dev/build-apps/event-handlers#compon... https://docs.budibase.com/docs/contextual-bindings https://docs.tooljet.com/docs/contributing-guide/setup/archi...