Hidden API

Reference for the hidden field declaration and behavior. For task-oriented examples, see the Hidden guide.

Declare the field inside a resource's fields method in app/avo/resources/post.rb:

field :user_id, as: :hidden

Declaration

The first argument identifies the record attribute, and as: :hidden selects the hidden input field. Hidden defines no field-specific options or validation rules. Shared options are documented in the Field options API, including default, visible, and html.

Visibility

By default, Hidden is restricted to the New and Edit forms. It does not render a visible label or control and is not displayed on Index or Show. The shared visible option can conditionally omit the input from a form.

Values and defaults

The input uses the field's resolved value, normally the record attribute. The shared default option defaults to nil; a configured default fills a nil attribute on New/Create, but does not replace an existing value or fill an empty value on Edit. Default blocks run in Avo::ExecutionContext, with access to current_user, record, resource, view, and parent.

Form submission

The field renders an HTML <input type="hidden"> through the resource form builder, using the field ID as the attribute name and the resolved field value as the input value. The browser submits it with the form despite the absence of a visible control. The shared html option supplies input classes, data attributes, and inline styles.

Hidden values are client-controlled

Hidden inputs are not an authorization mechanism. Their values can be inspected and changed before submission. Server-side authorization and validation still apply.