I have composite component:
<my:component value="#{bean.property1.property2}/>
From composite component I need to get class of bean.property1 to read its annotations.
I do it by the following code:
ValueExpression valueExpression = expressionFactory.createValueExpression(FacesContext.getCurrentInstance().getELContext(),
"#{bean.property1}", Object.class);
Object bean = valueExpression.getValue(FacesContext.getCurrentInstance().getELContext());
Class<?> beanClass = bean.getClass();
This works well but if I use my:component from a facelet and pass bean as a parameter via ui:param this does not work because bean can't be resolved.
Probably I should use FaceletContext as ELContext instead of FacesContext.getCurrentInstance().getELContext():
FaceletContext faceletElContext = (FaceletContext) FacesContext.getCurrentInstance().getAttributes()
.get("javax.faces.FACELET_CONTEXT");
But this doesn't work on RENDER_RESPONSE phase (from encodeBegin method). It returns last used ELContext instead of actual context (I am not surprised :) ).
The goal is to get class of #{bean.property1} from my:component. How can I do it?
This is easy with RichFaces:
ValueExpressionAnalayser analyser = new ValueExpressionAnalayserImpl();
ValueDescriptor valueDescriptor = analyser.getPropertyDescriptor(context, valueExpression);
Class<?> beanClass = valueDescriptor.getBeanType();
This is ok for me.
Also there is ValueExpressionAnalayzer in javax.faces.validator package but it is package private and can't be used.
You could pass the bean as a parameter to the component.
1) Declare the attribute in the component interface file(if you are using composite component):
<cc:interface componentType="myComponentClass">
<cc:attribute name="myBean" preferred="true"/>
..others attributes
<cc:interface>
2) Implement the respective getter and setter for "myBean" attribute in the component class(myComponentClass)
protected enum PropertyKeys {
myBean;
String toString;
PropertyKeys(String toString) {
this.toString = toString;
}
PropertyKeys() {}
#Override
public String toString() {
return ((this.toString != null) ? this.toString : super.toString());
}
}
public YourBeanClass getMyBean() {
return (YourBeanClass) getStateHelper().eval(PropertyKeys.myBean, null);
}
public void setMyBean(YourBeanClass myBean) {
getStateHelper().put(PropertyKeys.myBean, myBean);
}
3) Set the attribute on you jsf page:
<my:component myBean="#{bean}"/>
4) In the component's render class cast the UIComponent to myComponentClass.
#Override
public void encodeBegin(FacesContext pContext, UIComponent pComponent)
throws IOException {
myComponentClass myComponent = (myComponentClass) pComponent;
myComponent.getYourAttribute();
}
Related
I have used the HashMap method for binding a list of checkboxes to a Map<String, Boolean> with success. This is nice since it allows you to have a dynamic number of checkboxes.
I'm trying to extend that to a variable length list of selectManyMenu. Being that they are selectMany, I'd like to be able to bind to a Map<String, List<MyObject>>. I have a single example working where I can bind a single selectManyMenu to a List<MyObject> and everything works fine, but whey I put a dynamic number of selectManyMenus inside a ui:repeat and attempt to bind to the map, I end up with weird results. The values are stored correctly in the map, as verified by the debugger, and calling toString(), but the runtime thinks the map's values are of type Object and not List<MyObject> and throws ClassCastExceptions when I try to access the map's keys.
I'm guessing it has something to do with how JSF determines the runtime type of the target of your binding, and since I am binding to a value in a Map, it doesn't know to get the type from the value type parameter of the map. Is there any workaround to this, other than probably patching Mojarra?
In general, how can I have a page with a dynamic number of selectManyMenus? Without, of course using Primefaces' <p:solveThisProblemForMe> component. (In all seriousness, Primefaces is not an option here, due to factors outside of my control.)
The question UISelectMany on a List<T> causes java.lang.ClassCastException: java.lang.String cannot be cast to T had some good information that I wasn't aware of, but I'm still having issues with this SSCE:
JSF:
<ui:define name="content">
<h:form>
<ui:repeat value="#{testBean.itemCategories}" var="category">
<h:selectManyMenu value="#{testBean.selectedItemMap[category]}">
<f:selectItems value="#{testBean.availableItems}" var="item" itemValue="#{item}" itemLabel="#{item.name}"></f:selectItems>
<f:converter binding="#{itemConverter}"></f:converter>
<f:validator validatorId="test.itemValidator"></f:validator>
</h:selectManyMenu>
</ui:repeat>
<h:commandButton value="Submit">
<f:ajax listener="#{testBean.submitSelections}" execute="#form"></f:ajax>
</h:commandButton>
</h:form>
</ui:define>
Converter:
#Named
public class ItemConverter implements Converter {
#Inject
ItemStore itemStore;
#Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
return itemStore.getById(value);
}
#Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
return Optional.of(value)
.filter(v -> Item.class.isInstance(v))
.map(v -> ((Item) v).getId())
.orElse(null);
}
}
Backing Bean:
#Data
#Slf4j
#Named
#ViewScoped
public class TestBean implements Serializable {
private static final long serialVersionUID = 1L;
#Inject
ItemStore itemStore;
List<Item> availableItems;
List<String> itemCategories;
Map<String, List<Item>> selectedItemMap = new HashMap<>();
public void initialize() {
log.debug("Initialized TestBean");
availableItems = itemStore.getAllItems();
itemCategories = new ArrayList<>();
itemCategories.add("First Category");
itemCategories.add("Second Category");
itemCategories.add("Third Category");
}
public void submitSelections(AjaxBehaviorEvent event) {
log.debug("Submitted Selections");
selectedItemMap.entrySet().forEach(entry -> {
String key = entry.getKey();
List<Item> items = entry.getValue();
log.debug("Key: {}", key);
items.forEach(item -> {
log.debug(" Value: {}", item);
});
});
}
}
ItemStore just contains a HashMap and delegate methods to access Items by their ID field.
Item:
#Data
#Builder
public class Item {
private String id;
private String name;
private String value;
}
ItemListValidator:
#FacesValidator("test.itemValidator")
public class ItemListValidator implements Validator {
#Override
public void validate(FacesContext context, UIComponent component, Object value) throws ValidatorException {
if (List.class.isInstance(value)) {
if (((List) value).size() < 1) {
throw new ValidatorException(new FacesMessage(FacesMessage.SEVERITY_FATAL, "You must select at least 1 Admin Area", "You must select at least 1 Admin Area"));
}
}
}
}
Error:
java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to java.util.List
Stacktrace snipped but occurs on this line:
List<Item> items = entry.getValue();
What am I missing here?
As hinted in the related question UISelectMany on a List<T> causes java.lang.ClassCastException: java.lang.String cannot be cast to T, generic type arguments are unavailable during runtime. In other words, EL doesn't know you have a Map<String, List<Item>>. All EL knows is that you have a Map, so unless you explicitly specify a converter for the selected values, and a collection type for the collection, JSF will default to String for selected values and an object array Object[] for the collection. Do note that the [ in [Ljava.lang.Object indicates an array.
Given that you want the collection type to be an instance of java.util.List, you need to specify the collectionType attribute with the FQN of the desired concrete implementation.
<h:selectManyMenu ... collectionType="java.util.ArrayList">
JSF will then make sure that the right collection type is being instantiated in order to fill the selected items and put in the model. Here's a related question where such a solution is being used but then for a different reason: org.hibernate.LazyInitializationException at com.sun.faces.renderkit.html_basic.MenuRenderer.convertSelectManyValuesForModel.
Update: I should have tested the above theory. This doesn't work in Mojarra when the collection behind collectionType is in turn wrapped in another generic collection/map. Mojarra only checks the collectionType if the UISelectMany value itself already represents an instance of java.util.Collection. However, due to it being wrapped in a Map, its (raw) type becomes java.lang.Object and then Mojarra will skip the check for any collectionType.
MyFaces did a better job in this in its UISelectMany renderer, it works over there.
As far as I inspected Mojarra's source code, there's no way to work around this other way than replacing Map<String, List<Long>> by a List<Category> where Category is a custom object having String name and List<MyObject> selectedItems properties. True, this really kills the advantage of Map of having dynamic keys in EL, but it is what it is.
Here's a MCVE using Long as item type (just substitute it with your MyObject):
private List<Category> categories;
private List<Long> availableItems;
#PostConstruct
public void init() {
categories = Arrays.asList(new Category("one"), new Category("two"), new Category("three"));
availableItems = Arrays.asList(1L, 2L, 3L, 4L, 5L);
}
public void submit() {
categories.forEach(c -> {
System.out.println("Name: " + c.getName());
for (Long selectedItem : c.getSelectedItems()) {
System.out.println("Selected item: " + selectedItem);
}
});
// ...
}
public class Category {
private String name;
private List<Long> selectedItems;
public Category(String name) {
this.name = name;
}
// ...
}
<h:form>
<ui:repeat value="#{bean.categories}" var="category">
<h:selectManyMenu value="#{category.selectedItems}" converter="javax.faces.Long">
<f:selectItems value="#{bean.availableItems}" />
</h:selectManyMenu>
</ui:repeat>
<h:commandButton value="submit" action="#{bean.submit}">
<f:ajax execute="#form" />
</h:commandButton>
</h:form>
Do note that collectionType is unnecessary here. Only the converter is still necessary.
Unrelated to the concrete problem, I'd like to point out that selectedItemMap.entrySet().forEach(entry -> { String key ...; List<Item> items ...;}) can be simplified to selectedItemMap.forEach((key, items) -> {}) and that ItemListValidator is unnecessary if you just use required="true" on the input component.
I'm trying to develop a custom component that will need to call a method from the backingbean to get some data from the bb (this will be called in the decode phase after a certain Ajax call) with one parameter (it will come in the ajax call).
The problem I'm having is that I define the attribute as a MethodExpression (in the taglibrary and the component), I get the Ajax post, decode the parameter and when I try to get the Method binding from the component I get the following error:
javax.el.PropertyNotFoundException: /easyFaces.xhtml #19,151
dataSource="#{theBean.loadDataFromSource}": The class
'ar.com.easytech.faces.test.homeBean' does not have the property
'loadDataFromBean'.
Here is the relevant code.. (and please let me know if this is not the correct way to do this..)
taglib:
<attribute>
<display-name>Data Source</display-name>
<name>dataSource</name>
<required>true</required>
<type>javax.el.MethodExpression</type>
<method-signature>java.util.List theDataSource(java.lang.String)</method-signature>
</attribute>
Component definition:
public class Autocomplete extends HtmlInputText implements ClientBehaviorHolder
...
public MethodExpression getDataSource() {
return (MethodExpression) getStateHelper().eval(PropertyKeys.dataSource);
}
public void setDataSource(MethodExpression dataSource) {
getStateHelper().put(PropertyKeys.dataSource, dataSource);
}
and finally the rendered method that generates the error:
private List<Object> getData(FacesContext context, Autocomplete autocomplete, String data) {
Object dataObject = null;
MethodExpression dataSource = autocomplete.getDataSource();
if (dataSource != null) {
try {
dataObject = dataSource.invoke(context.getELContext(), new Object[] {data});
return convertToList(dataObject);
} catch (MethodNotFoundException e) {
logger.log(Level.INFO,"Method not found: {0}", dataSource.getExpressionString() );
}
}
return null;
}
Here is the method from the BB
public List<String> autcompleteFromSource(String param) {
List<String> tmpData = new ArrayList<String>();
tmpData.add("XXA_TABLE_A");
tmpData.add("XXA_TABLE_B");
tmpData.add("XXA_TABLE_C");
return tmpData;
}
And the .xhtml with the component
<et:autocomplete id="autoc" minLength="3" delay="500" value="#{easyfacesBean.selectedValue}" dataSource="#{easyfacesBean.autcompleteFromSource}" />
The thing is if I define a method getAutocompleteFromSource() it recognised the method and the error changes to can't convert list to MethodExpression, so evidently it is simply interpreting the autocompleteFromSource as a simple property and not a method definition, is this even the correct way to call method from BB? (giving that it's not an actual action nor validation )
I found the solution for this, as it turns out you also need to define a "Handler"to define the Method Signature, so I created the handler and added to the taglib and everything started to work fine..just for reference.. here is the handler..
Regards
public class AutocompleteHandler extends ComponentHandler {
public AutocompleteHandler(ComponentConfig config) {
super(config);
}
protected MetaRuleset createMetaRuleset(Class type) {
MetaRuleset metaRuleset = super.createMetaRuleset(type);
metaRuleset.addRule(new MethodRule("dataSource", List.class, new Class[] { String.class }));
return metaRuleset;
}
}
I'm probably too blind and too new to OmniFaces, and could not find a basic method in the API to retrieve a backing bean instance. Where can I find such a method if there is one? Like this one:
public static Object getBackingBean(String name) {
FacesContext context = FacesContext.getCurrentInstance();
Application app = context.getApplication();
ValueExpression expression = app.getExpressionFactory()
.createValueExpression(context.getELContext(), String.format("#{%s}", name), Object.class);
return expression.getValue(context.getELContext());
}
Or a more dynamic version with generics:
public static <T> T getBackingBean(String name) {
FacesContext context = FacesContext.getCurrentInstance();
Application app = context.getApplication();
ValueExpression expression = app.getExpressionFactory()
.createValueExpression(context.getELContext(), String.format("#{%s}", name), Object.class);
return (T) expression.getValue(context.getELContext());
}
We have a method that's nearly like that, but it can evaluate (and get) any kind of expression not just a simplified root expression.
It's Faces.evaluateExpressionGet.
You use it as follows:
MyBean myBean = Faces.evaluateExpressionGet("#{myBean}");
With MyBean being e.g. defined as follows:
#ViewScoped
#ManagedBean
public class MyBean {
// ...
}
Following java code allows to access any object or variable from faces context:
ELContext elCtx = facesContext.getELContext();
ExpressionFactory exprFac = facesContext.getApplication().getExpressionFactory();
MyProperty myProperty = (MyProperty) exprFac.createValueExpression(elCtx, "#{somebean.someattr.someproperty}", MyProperty.class).getValue(elCtx);
I use the code from within my custom converter to read additional converting parameters from context.
The code works correctly if #{somebean} is defined as normal backing bean within JSF context.
Facelets allow to create 'shortcut' to JSF expressions. Example:
<ui:param name="shortcut" value="#{somebean.someattr.someproperty}" />
<div>#{somebean.someattr.someproperty} equals #{shortcut}</div>
In this case both #{somebean.someattr.someproperty} and #{shortcut} have the same value.
However these 'shortcut' names are not accessible using java code above. For example:
MyProperty myProperty1 = (MyProperty) exprFac.createValueExpression(elCtx, "#{somebean.someattr.someproperty}", MyProperty.class).getValue(elCtx);
// myProperty1 has expected value
MyProperty myProperty2 = (MyProperty) exprFac.createValueExpression(elCtx, "#{shortcut}", MyProperty.class).getValue(elCtx);
// myProperty2 is null
Is there a way to access a facelets context and to read 'shortcut' parameter values, defined on the current JSF page?
I had the same problem and have chosen the following approach:
/**
* Führt eine Expression im aktuellen Faces EL Context
* UND im Facelets El Context aus.
*
* #param facesContext
* #param expression
* #return object
*/
private static Object executeExpressionInUIContext (final FacesContext facesContext, final String expression) {
final ELContext elContext = facesContext.getELContext();
final Application application = facesContext.getApplication();
Object result = executeExpressionInElContext(application, elContext, expression);
if (null == result) {
FaceletContext faceletElContext = (FaceletContext) FacesContext.getCurrentInstance().getAttributes().get(FaceletContext.FACELET_CONTEXT_KEY);
result = executeExpressionInElContext(application, faceletElContext, expression);
}
return result;
}
private static Object executeExpressionInElContext (Application application, ELContext elContext, String expression) {
ExpressionFactory expressionFactory = application.getExpressionFactory();
ValueExpression exp = expressionFactory.createValueExpression(elContext, expression, Object.class);
return exp.getValue(elContext);
}
"ui:param" is part of the Facelet view handling technology. Facelets extends JSF.
Both technologies use their own Context when storing variables.
Beside the Faces El Context there is a Facelet El Context (FaceletContext).
The stated method evaluates expressions in both contexts. Be aware that this will not work if two values are stored under the same name in each context.
It seems that facelet shortcuts do not exist in the context, where I try to access them.
I have made following workaround: On JSF page where my input element is placed, I have added a <f:param> element as child of the input with my converter.
<h:inputText id="myid" value="#{action.myinput}">
<f:converter converterId="myConverter" />
<f:param name="converterParameters" shortcut="#{somebean.someattr.someproperty}"/>
</h:inputText>
Then in converter I'm able to find UIParam element as one of the input children and read my shortcuts from it.
public Object getAsObject(FacesContext context, UIComponent component, String value) {
MyProperty myProperty = null;
try {
for (final UIComponent child : component.getChildren()) {
if ("converterParameters".equals(child.getAttributes().get("name"))) {
final ELContext elCtx = context.getELContext();
myProperty = (MyProperty) child.getValueExpression("shortcut").getValue(elCtx);
break;
}
}
if (myProperty == null) {
throw new NullPointerException("My property is undefined.");
}
} catch (Exception e) {
LOG.error("Cannot convert " + value + ". Use <f:param name=\"converterParameters\" "
+ "shortcut=\"#{here.comes.shortcut}\"/> for your input element. ", e);
throw new ConverterException("Cannot initialize converter.", e);
}
//...
}
The mapping of ui:param is not stored in context, it's in the VariableMapper of each individual ValueExpression.
So if you need to create ValueExpression programmatically, relying on another ValueExpression's varMapper, you can do something like this:
VariableMapper varMapper = new DefaultVariableMapper();
varMapper.setVariable(mappingName, component.getValueExpression(mappedAttributeName));
return new ValueExpressionImpl(expression, null, null, varMapper, expectedType);
I know about startElement, endElement, and writeAttribute methods on ResponseWriter. My problem is that I want to for example output a h:commandLink by declaring it like HtmlCommandLink link = new HtmlCommandLink(); .
How can I output other UIComponents like this in my own component? I might want to use some RichFaces ajax stuff in my components aswell so hoping I can avoid making it all by scratch.
Edit: What I'm trying to do is create my own tag library with the following tag <myTags:commentTree>. Every comment have a reply button, when the reply button is clicked I render the reply form beneath the comment. Once that is rendered, I would like to output for example the richfaces <a4j:commandButton> component. This have to be done inside my own java tag file which Ive called for CommentsTreeUI.java.
Normally I output all my elements that display the forms and buttons with writer.startElement("input", myComponent); writer.writeAttribute("type", "button", null); but if I could instead do for example startElement("a4j:commandbutton", myComponent) that would help my ALOT since it has all the built in ajax features etc.
Any clues?
This problem was solved by adding new components by using
HtmlCommandButton button = new HtmlCommandButton();
button.encodeAll(context);
You can do something like this:
HtmlCommandLink link = new HtmlCommandLink();
getChildren().add(link);
It does depend on what you want to do with the child components though i.e. if you want them surrounded with custom HTML (in an HTML list, for example) you will need something a bit more complex.
One approach to making composite controls is to use the binding attribute to associate the tag with your own code:
<f:view>
<h:form>
<h:panelGroup binding="#{compositeControlBean.panelGrid}" />
</h:form>
</f:view>
The bean configuration in faces-config.xml:
<managed-bean>
<managed-bean-name>compositeControlBean</managed-bean-name>
<managed-bean-class>
composite.CompositeControlBean
</managed-bean-class>
<managed-bean-scope>request</managed-bean-scope>
</managed-bean>
The bean code:
/**
* Configure this bean in request scope as "compositeControlBean".
*/
public class CompositeControlBean {
private transient UIComponent panelGrid;
public UIComponent getPanelGrid() {
if (panelGrid == null) {
panelGrid = createCompositePanel();
}
return panelGrid;
}
public void setPanelGrid(UIComponent panelGrid) {
this.panelGrid = panelGrid;
}
private UIComponent createCompositePanel() {
initContextMemebers();
UIComponent commandLink = createCommandLink();
String id = view.createUniqueId();
UIComponent panelGrid = application
.createComponent("javax.faces.HtmlPanelGroup");
panelGrid.setId(id);
panelGrid.setRendererType("javax.faces.Group");
panelGrid.getChildren().add(commandLink);
return panelGrid;
}
private UIComponent createCommandLink() {
// create control
String id = view.createUniqueId();
UIComponent commandLink = application
.createComponent("javax.faces.HtmlCommandLink");
commandLink.setId(id);
commandLink.setRendererType("javax.faces.Link");
// set attributes (bind to printHello method)
Map<String, Object> attributes = commandLink
.getAttributes();
MethodExpression action = expressionFactory
.createMethodExpression(elContext,
"#{compositeControlBean.printHello}",
String.class, new Class<?>[0]);
attributes.put("value", "print hello");
attributes.put("actionExpression", action);
return commandLink;
}
private transient FacesContext context;
private transient Application application;
private transient ELContext elContext;
private transient ExpressionFactory expressionFactory;
private transient UIViewRoot view;
private void initContextMemebers() {
context = FacesContext.getCurrentInstance();
application = context.getApplication();
elContext = context.getELContext();
expressionFactory = application.getExpressionFactory();
view = context.getViewRoot();
}
public String printHello() {
System.out.println("Hello");
return null;
}
}