Module org.omnifaces
Package org.omnifaces.component.input

Class HashParam

  • All Implemented Interfaces:
    EditableValueHolder, PartialStateHolder, StateHolder, TransientStateHolder, ValueHolder, ComponentSystemEventListener, FacesListener, SystemEventListenerHolder, EventListener
    public class HashParam
extends OnloadParam

    The <o:hashParam> is a component that extends the standard <f:viewParam> with support for setting hash query parameter values in bean and automatically reflecting updated model values in hash query string.

    The "hash query string" is the part in URL after the # which could be formatted in the same format as a regular request query string (the part in URL after the ?). An example: 

     https://example.com/page.xhtml#foo=baz&bar=kaz

    This specific part of the URL (also called hash fragment identifier) is by default not sent to the server. This component will on page load and on every window.onhashchange event send it anyway so that the Faces model gets updated, and on every Faces ajax request update the hash query string in client side when the Faces model value has changed.

    Usage

    It's very similar to the <o:viewParam>. 

     <f:metadata>
     <o:hashParam name="foo" value="#{bean.foo}" />
     <o:hashParam name="bar" value="#{bean.bar}" />
 </f:metadata>

    You can use the render attribute to declare which components should be updated when a hash parameter value is present. 

     <f:metadata>
     <o:hashParam name="foo" value="#{bean.foo}" render="fooResult" />
     <o:hashParam name="bar" value="#{bean.bar}" />
 </f:metadata>
 ...
 <h:body>
     ...
     <h:panelGroup id="fooResult">
         ...
     </h:panelGroup>
     ...
 </h:body>

    In case you need to invoke a bean method before rendering, e.g. to preload the rendered contents based on new hash param values, then you can observe the HashChangeEvent. See the "Events" section for an usage example.

    You can use the default attribute to declare a non-null value which should be interpreted as the default value. In other words, when the current model value matches the default value, then the hash parameter will be removed. 

     <f:metadata>
     <o:hashParam name="foo" value="#{bean.foo}" />
     <o:hashParam name="bar" value="#{bean.bar}" default="kaz" />
 </f:metadata>

    When #{bean.foo} is "baz" and #{bean.bar} is "kaz" or empty, then the reflected hash query string will become https://example.com/page.xhtml#foo=baz. If #{bean.bar} is any other value, then it will appear in the hash query string.

    Note that as it extends from the standard <f:viewParam>, its built-in conversion and validation functionality is also supported on this component.

    Events

    When the hash query string is changed by the client side, e.g. by following a #foo=baz&bar=kaz link, or by manually manipulating the URL, then a CDI HashChangeEvent will be fired which can be observed in any CDI managed bean as below: 

     public void onHashChange(@Observes HashChangeEvent event) {
     String oldHashString = event.getOldValue();
     String newHashString = event.getNewValue();
     // ...
 }

    This is useful in case you want to preload the model for whatever is rendered by <o:hashParam render>.

    Since:
    3.2
    Author:
    Bauke Scholtz
    See Also:
    OnloadParam, HashChangeEvent, Faces.getHashParameters(), Faces.getHashParameterMap(), Faces.getHashQueryString()

    • Field Detail

      • COMPONENT_TYPE

        public static final String COMPONENT_TYPE
        The component type, which is "org.omnifaces.component.input.HashParam".
        See Also:
        Constant Field Values

      • EVENT_VALUE

        public static final String EVENT_VALUE
        The omnifaces event value, which is "setHashParamValues".
        See Also:
        Constant Field Values

    • Constructor Detail

      • HashParam

        public HashParam()

    • Method Detail

      • getInitScript

        protected String getInitScript​(FacesContext context)
        Description copied from class: OnloadParam
        Returns script which should be executed upon initialization of a new view.
        Overrides:
        getInitScript in class OnloadParam
        Parameters:
        context - The involved faces context.
        Returns:
        Script which should be executed upon initialization of a new view.

      • getUpdateScript

        protected String getUpdateScript​(FacesContext context)
        Description copied from class: OnloadParam
        Returns script which should be exeucted upon ajax update of the current view.
        Overrides:
        getUpdateScript in class OnloadParam
        Parameters:
        context - The involved faces context.
        Returns:
        Script which should be exeucted upon ajax update of the current view.

      • getRenderedValue

        public String getRenderedValue​(FacesContext context)
        Convert the value to string using any converter and ensure that an empty string is returned when the component is invalid or the resulting string is null or represents the default value.
        Parameters:
        context - The involved faces context.
        Returns:
        The rendered value.

      • getDefault

        public String getDefault()
        Returns the default value in case the actual hash parameter is null or empty.
        Returns:
        The default value in case the actual hash parameter is null or empty.

      • setDefault

        public void setDefault​(String defaultValue)
        Sets the default value in case the actual hash parameter is null or empty.
        Parameters:
        defaultValue - The default value in case the actual hash parameter is null or empty.

      • isHashParamRequest

        public static boolean isHashParamRequest​(FacesContext context)
        Returns true if the current request is triggered by a hash param request. I.e. if it is initiated by OmniFaces.HashParam.setHashParamValues() script which runs on page load when the window.location.hash is present, and on every window.onhashchange event.
        Parameters:
        context - The involved faces context.
        Returns:
        true if the current request is triggered by a hash param request.