Validation

Mateu supports standard Java Bean Validation annotations.

Validation rules defined in your backend models are automatically enforced in the UI.

Example

@NotEmpty
String name;

@Email
String email;

@Size(min = 8)
String password;

Mateu uses these annotations to:

• validate input in the browser
• prevent invalid submissions
• keep backend and UI validation consistent

Why this matters

In traditional architectures, validation is duplicated:

• backend validation
• frontend validation

With Mateu:

• validation is defined once
• applied everywhere

Mental model

Validation is part of your domain model.

Mateu propagates it to the UI automatically.