org.omnifaces.component.input

Class ViewParam

java.lang.Object

javax.faces.component.UIComponent

javax.faces.component.UIComponentBase

javax.faces.component.UIOutput

javax.faces.component.UIInput

javax.faces.component.UIViewParameter

org.omnifaces.component.input.ViewParam

All Implemented Interfaces:

EventListener, EditableValueHolder, PartialStateHolder, StateHolder, TransientStateHolder, ValueHolder, ComponentSystemEventListener, FacesListener, SystemEventListenerHolder

Direct Known Subclasses:

ComponentIdParam

public class ViewParam
extends UIViewParameter

The <o:viewParam> is a component that extends the standard <f:viewParam> and provides a stateless mode of operation and fixes the issue wherein null model values are converted to empty string parameters in query string (e.g. when includeViewParams=true) and the (bean) validation never being triggered when the parameter is completely absent in query string, causing e.g. @NotNull to fail.

Stateless mode to avoid unnecessary conversion, validation and model updating on postbacks

The standard UIViewParameter implementation calls the model setter again after postback. This is not always desired when being bound to a view scoped bean and can lead to performance problems when combined with an expensive converter. To solve this, this component by default stores the submitted value as a component property instead of in the model (and thus in the view state in case the binding is to a view scoped bean).

The standard UIViewParameter implementation calls the converter and validators again on postbacks. This is not always desired when you have e.g. a required="true", but the parameter is not retained on form submit. You would need to retain it on every single command link/button by <f:param>. To solve this, this component doesn't call the converter and validators again on postbacks.

Using name as default for label

The <o:viewParam> also provides a default for the label atrribute. When the label attribute is omitted, the name attribute will be used as label.

Avoid unnecessary empty parameter in query string

The standard UIViewParameter implementation calls the converter regardless of whether the evaluated model value is null or not. As converters by specification return an empty string in case of null value, this is being added to the query string as an empty parameter when e.g. includeViewParams=true is used. This is not desired. The workaround was added in OmniFaces 1.8.

Support bean validation and triggering validate events on null value

The standard UIViewParameter implementation uses in JSF 2.0-2.2 an internal "is required" check when the submitted value is null, hereby completely bypassing the standard UIInput validation, including any bean validation annotations and even the PreValidateEvent and PostValidateEvent events. This is not desired. The workaround was added in OmniFaces 2.0. In JSF 2.3, this has been fixed and has only effect when javax.faces.INTERPRET_EMPTY_STRING_SUBMITTED_VALUES_AS_NULL context param is set to true.

Default value when no parameter is set

The <o:viewParam> also supports providing a default value via the new default attribute. When the parameter is not available, then the value specified in default attribute will be set in the model instead. The support was added in OmniFaces 2.2.

Usage

You can use it the same way as <f:viewParam>, you only need to change f: to o:.

 <o:viewParam name="foo" value="#{bean.foo}" />
 

Author:

Arjan Tijms, Bauke Scholtz

Nested Class Summary

Nested classes/interfaces inherited from class javax.faces.component.UIViewParameter

UIViewParameter.Reference

Field Summary

Fields

Modifier and Type	Field and Description
static String	COMPONENT_TYPE

Fields inherited from class javax.faces.component.UIViewParameter

COMPONENT_FAMILY

Fields inherited from class javax.faces.component.UIInput

CONVERSION_MESSAGE_ID, REQUIRED_MESSAGE_ID, UPDATE_MESSAGE_ID, VALIDATE_EMPTY_FIELDS_PARAM_NAME

Fields inherited from class javax.faces.component.UIComponent

ATTRS_WITH_DECLARED_DEFAULT_VALUES, BEANINFO_KEY, bindings, COMPOSITE_COMPONENT_TYPE_KEY, COMPOSITE_FACET_NAME, CURRENT_COMPONENT, CURRENT_COMPOSITE_COMPONENT, FACETS_KEY, HONOR_CURRENT_COMPONENT_ATTRIBUTES_PARAM_NAME, VIEW_LOCATION_KEY

Constructor Summary

Constructors

Constructor and Description
ViewParam()

Method Summary

Modifier and Type	Method and Description
Map<String,Object>	getAttributes()
String	getDefault() Returns the default value in case the actual request parameter is null or empty.
String	getStringValueFromModel(FacesContext context) When there's a value expression and the evaluated model value is null, then just return null instead of delegating to default implementation which would return an empty string when a converter is attached.
String	getSubmittedValue()
boolean	isRequired()
void	processDecodes(FacesContext context)
void	processValidators(FacesContext context)
void	setDefault(String defaultValue) Sets the default value in case the actual request parameter is null or empty.
void	setSubmittedValue(Object submittedValue)

Methods inherited from class javax.faces.component.UIViewParameter

decode, encodeAll, getConvertedValue, getFamily, getName, getStringValue, isImmediate, setName, updateModel

Methods inherited from class javax.faces.component.UIInput

addValidator, addValueChangeListener, clearInitialState, compareValues, getConverterMessage, getRequiredMessage, getValidator, getValidatorMessage, getValidators, getValue, getValueChangeListener, getValueChangeListeners, isEmpty, isLocalValueSet, isValid, markInitialState, processUpdates, removeValidator, removeValueChangeListener, resetValue, restoreState, saveState, setConverterMessage, setImmediate, setLocalValueSet, setRequired, setRequiredMessage, setValid, setValidator, setValidatorMessage, setValue, setValueChangeListener, validate, validateValue

Methods inherited from class javax.faces.component.UIOutput

getConverter, getLocalValue, setConverter

Methods inherited from class javax.faces.component.UIComponentBase

addClientBehavior, addFacesListener, broadcast, encodeBegin, encodeChildren, encodeEnd, findComponent, getChildCount, getChildren, getClientBehaviors, getClientId, getDefaultEventName, getEventNames, getFacesContext, getFacesListeners, getFacet, getFacetCount, getFacets, getFacetsAndChildren, getId, getListenersForEventClass, getParent, getPassThroughAttributes, getRenderer, getRendererType, getRendersChildren, getValueBinding, invokeOnComponent, isRendered, isTransient, processRestoreState, processSaveState, queueEvent, removeFacesListener, restoreAttachedState, saveAttachedState, setId, setParent, setRendered, setRendererType, setTransient, setValueBinding, subscribeToEvent, unsubscribeFromEvent

Methods inherited from class javax.faces.component.UIComponent

getClientId, getCompositeComponentParent, getContainerClientId, getCurrentComponent, getCurrentCompositeComponent, getNamingContainer, getPassThroughAttributes, getResourceBundleMap, getStateHelper, getStateHelper, getTransientStateHelper, getTransientStateHelper, getValueExpression, initialStateMarked, isCompositeComponent, isInView, isVisitable, popComponentFromEL, processEvent, pushComponentToEL, restoreTransientState, saveTransientState, setInView, setValueExpression, visitTree

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface javax.faces.component.ValueHolder

getConverter, getLocalValue, setConverter

Field Detail

COMPONENT_TYPE

public static final String COMPONENT_TYPE

See Also:

Constant Field Values

Constructor Detail

ViewParam

public ViewParam()

Method Detail

processDecodes

public void processDecodes(FacesContext context)

Overrides:

processDecodes in class UIInput

processValidators

public void processValidators(FacesContext context)

Overrides:

processValidators in class UIViewParameter

getAttributes

public Map<String,Object> getAttributes()

Overrides:

getAttributes in class UIComponentBase

getStringValueFromModel

public String getStringValueFromModel(FacesContext context)
                               throws ConverterException

When there's a value expression and the evaluated model value is null, then just return null instead of delegating to default implementation which would return an empty string when a converter is attached.

Overrides:

getStringValueFromModel in class UIViewParameter

Throws:

ConverterException

Since:

1.8

getSubmittedValue

public String getSubmittedValue()

Specified by:

getSubmittedValue in interface EditableValueHolder

Overrides:

getSubmittedValue in class UIViewParameter

setSubmittedValue

public void setSubmittedValue(Object submittedValue)

Specified by:

setSubmittedValue in interface EditableValueHolder

Overrides:

setSubmittedValue in class UIViewParameter

getDefault

public String getDefault()

Returns the default value in case the actual request parameter is null or empty.

Returns:

The default value in case the actual request parameter is null or empty.

Since:

2.2

setDefault

public void setDefault(String defaultValue)

Sets the default value in case the actual request parameter is null or empty.

Parameters:

defaultValue - The default value in case the actual request parameter is null or empty.

Since:

2.2

isRequired

public boolean isRequired()

Specified by:

isRequired in interface EditableValueHolder

Overrides:

isRequired in class UIInput