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So, this is a basic (very basic!) form and you can leave the fields blank and submit the form. With very little effort we can add client-side validation, to prevent the user from submitting the form with either field left blank.

Validation in Tapestry involves associating one or more validators with a form element component, such as TextField or PasswordField. This can be done using the validate parameter of the component itself.

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The annotation may be placed on the getter or setter method, or on the field itself.

Update the two fields of the Login page:

  @Persist
  @Property
  @Validate("required")
  private String userName;

  @Property
  @Validate("required")
 private String password;

Now, rebuild the app, refresh the browser, and just hit enter:

Customizing Validation Messages

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