---
lang: en
title: 'Validation in ORM Layer'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
permalink: /doc/en/lb4/Validation-ORM-layer.html
---

The validation in the ORM layer is to make sure the data being added or updated
to the database is valid.

Schema constraints are enforced by specific databases, such as unique index. For
pre-processing against CRUD operations, see details:
https://loopback.io/doc/en/lb4/migration-models-operation-hooks.html.
