see on GitHub

Session: How to Customize the Identity Property Lookup for Entities

The client must know which property of your entity is considered as an identity. By default, it always looks for the id field (case-sensitive). This behavior can be changed by overwriting one of our conventions called identityProperty.

Syntax

store.conventions.identityProperty;

Example

Here's how to change it to Identifier field.

store.conventions.identityProperty = "Identifier";