Interface NamingContainer

All Known Implementing Classes:
HtmlDataTable, HtmlForm, UIData, UIForm, UINamingContainer

public interface NamingContainer
Interface implemented by components that provide a new "namespace" for the ids of their child components.

Component ids must be unique between all descendants of a NamingContainer; the Faces library will report a fatal error and refuse to process or render any view where two components in the same NamingContainer have identical id values. However a component that is a descendant of one NamingContainer component is permitted to have the same id as a component that is a descendant of a different NamingContainer component.

Unique component ids are used to:

  • generate unique names for HTML form fields, etc
  • search for components via UIComponent.findComponent(String expr)
  • on re-render after postback, match up component declarations in the view templates with existing components in the restored view tree.

Requiring every component in a large view (which is possibly built by including or composing multiple files together) to have an id which is different from every other id is simply unmanageable; Faces certainly must provide some kind of id namespacing. Therefore this base class is defined, and a few standard Faces components subclass it (in particular, f:subview).

When generating clientId values during rendering, descendants of a NamingContainer instance are allocated a clientId which is their own id prefixed with the clientId of the ancestor NamingContainer, eg "parentId:childId". NamingContainer components can be nested within other NamingContainer components, generating clientIds like "firstId:middleId:leafId".

Not every component is a naming container; that would technically work, but the clientId values generated would quickly grow excessively long.

See the javadoc for this class in the Faces Specification for further details.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final char
    The separator character used in component identifiers to demarcate navigation to a child naming container.
  • Field Details

    • SEPARATOR_CHAR

      static final char SEPARATOR_CHAR

      The separator character used in component identifiers to demarcate navigation to a child naming container. The default separator character used in component identifiers to demarcate navigation to a child naming container, in case UINamingContainer.getSeparatorChar(jakarta.faces.context.FacesContext) does not resolve to a valid value. It is not recommended to use this value directly, the {link UINamingContainer#getSeparatorChar(jakarta.faces.context.FacesContext)} must be used instead.

      See Also: