[keycloak-user] Customer Properties in Registration Page

Is there way to validate a "custom" property? My use case is that I am registering a customer for a portal application. I want to validate the entered customer # (custom property) against a table that maps the email address with a customer. This validation must pass in order to allow a user to be registered. Thank you -- Michael J. Hills Sr. CRM Architect Mobile: 603.475.5093 Email : mike.hills(a)sematree.com Skype : mhills_sematree