Following on from the response by the legendary BalusC to this post:
How to programmatically or dynamically create a composite component in JSF 2
Had I sufficient points I would attach a comment to that post -- but I don't have sufficient points .
Problem as follows.
I'm trying to set up a commandButton which adds a JSF composite component dynamically to an xhtml file. With the intention that clicking it multiple times will put multiple instances of the component on the page.
So I have a button on an XHTML file:
<h:commandButton action="#{assessingController.addQuestion}" value="Add a Question"></h:commandButton>
Which calls a method on AssessingController:
public void addQuestion() {
UIComponent parent = null;
includeCompositeComponent(parent, "http://xmlns.jcp.org/jsf/composite/components", "questionComposite", "someId");
}
UIComponent parent = null; -- because it has to be instantiated or referenced somehow, before being passed into includeCompositeComponent . But as noted below - making it null might be causing the null pointer exception, (so what should I do instead?)
includeCompositeComponent method is as per the JSF 2.2 method referred to by BalusC in the above post:
public void includeCompositeComponent(UIComponent parent, String taglibURI, String tagName, String id) {
FacesContext context = FacesContext.getCurrentInstance();
UIComponent composite = context.getApplication().getViewHandler()
.getViewDeclarationLanguage(context, context.getViewRoot().getViewId())
.createComponent(context, taglibURI, tagName, null);
composite.setId(id);
parent.getChildren().add(composite);
}
When I click on the commandButton, logs as follows:
javax.faces.el.EvaluationException: java.lang.NullPointerException
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:101)
at com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:102)
at javax.faces.component.UICommand.broadcast(UICommand.java:315) ...
Caused by: java.lang.NullPointerException
at controllers.AssessingController.includeCompositeComponent(AssessingController.java:123)
AssessingController.java:123 is this line:
parent.getChildren().add(composite);
Composite is not null (checked that).
So, obviously perhaps, - parent is null and that's where the problem is.
So how can I better reference UIComponent parent to begin with?
Do I need to make it refer to something on the xhtml file? I'm presuming it needs some kind of a placeholder which will serve as the parent(?). Right now all there is on the xhtml page is the commandButton.
Thank you all.
The parent is supposed to represent the component where you'd like to include the composite component in.
Imagine that you ultimately want to end up with this plain XHTML representation:
<h:panelGroup id="questions">
<your:questionComposite />
</h:panelGroup>
You should then supply exactly that <h:panelGroup> component as parent.
<h:form>
<h:commandButton ... action="#{bean.addQuestion}" />
</h:form>
<h:panelGroup id="questions" />
public void addQuestion() {
UIComponent parent = context.getViewRoot().findComponent("questions");
// ...
}
Or, by passing the concrete component itself:
<h:form>
<h:commandButton ... action="#{bean.addQuestion(questions)}" />
</h:form>
<h:panelGroup id="questions" binding="#{questions}" />
public void addQuestion(UIComponent parent) {
// ...
}
Unrelated to the concrete problem: there's a thinking/design mistake here. You should rather use an <ui:repeat><your:compositeComponent> and then feed from a #ViewScoped bean to the <ui:repeat> a dynamically sized list of entities representing the composite's model value.
<h:form>
<h:commandButton ... action="#{bean.addQuestion}" />
</h:form>
<ui:repeat value="#{bean.questions}" var="question">
<your:questionComposite value="#{question}" />
</ui:repeat>
private List<Question> questions;
public void addQuestion() {
questions.add(new Question());
}
Anytime you need to deal with raw UIComponent instances in a backing bean, take a pause and carefully research or ask if you're really doing things the right way. Perhaps it belongs in a backing component instead, or could just be done with pure XHTML.
See also:
How to dynamically add JSF components
How does the 'binding' attribute work in JSF? When and how should it be used?
Related
I have a custom component that implements UIInput and that needs to save some state info for later reuse in postback requests. Used standalone it works fine, but inside an <ui:repeat> the postback finds the saved state of the latest rendered row of data. The log output of an action call is
INFORMATION: myData is "third foo"
INFORMATION: myData is "third foo"
INFORMATION: myData is "third foo"
INFORMATION: ok action
where I would expect
INFORMATION: myData is "first foo"
INFORMATION: myData is "second foo"
INFORMATION: myData is "third foo"
INFORMATION: ok action
I understand that myComponent is a single instance inside of ui:repeat. So what is the best way to save component state so it is restored correctly for each row in the dataset?
My XHTML form:
<h:form>
<ui:repeat var="s" value="#{myController.data}">
<my:myComponent data="#{s}"/>
</ui:repeat>
<h:commandButton action="#{myController.okAction}" value="ok">
<f:ajax execute="#form" render="#form"/>
</h:commandButton>
</h:form>
My Bean:
#Named
#ViewScoped
public class MyController implements Serializable {
private static final long serialVersionUID = -2916212210553809L;
private static final Logger LOG = Logger.getLogger(MyController.class.getName());
public List<String> getData() {
return Arrays.asList("first","second","third");
}
public void okAction() {
LOG.info("ok action");
}
}
Composite component XHTML code:
<ui:component xmlns="http://www.w3.org/1999/xhtml"
xmlns:h="http://xmlns.jcp.org/jsf/html"
xmlns:ui="http://xmlns.jcp.org/jsf/facelets"
xmlns:cc="http://xmlns.jcp.org/jsf/composite">
<cc:interface componentType="myComponent">
<cc:attribute name="data"/>
</cc:interface>
<cc:implementation>
<h:panelGrid columns="2">
<h:outputLabel value="cc.attrs.data"/>
<h:outputText value="#{cc.attrs.data}"/>
<h:outputLabel value="cc.myData"/>
<h:outputText value="#{cc.myData}"/>
</h:panelGrid>
</cc:implementation>
</ui:component>
Composite Component backing class:
#FacesComponent
public class MyComponent extends UIInput implements NamingContainer {
private static final Logger LOG=Logger.getLogger(MyComponent.class.getName());
public String calculateData() {
return String.format("%s foo", this.getAttributes().get("data") );
}
public String getMyData() {
return (String)getStateHelper().get("MYDATA");
}
public void setMyData( String data ) {
getStateHelper().put("MYDATA", data);
}
#Override
public String getFamily() {
return UINamingContainer.COMPONENT_FAMILY;
}
#Override
public void encodeBegin(FacesContext context) throws IOException {
this.setMyData( calculateData() );
super.encodeBegin(context);
}
#Override
public void processDecodes(FacesContext context) {
super.processDecodes(context);
LOG.log(Level.INFO, "myData {0}", getMyData() );
}
}
Just tried reproducing your issue and yes, now I get what you're after all. You just wanted to use the JSF component state as some sort of view scope for the calculated variables. I can understand that. The observed behavior is indeed unexpected.
In a nutshell, this is explained in this blog of Leonardo Uribe (MyFaces committer): JSF component state per row for datatables.
The reason behind this behavior is tags like h:dataTable or ui:repeat only save properties related with EditableValueHolder interface (value, submittedValue, localValueSet, valid). So, a common hack found to make it work correctly is extend your component from UIInput or use EditableValueHolder interface, and store the state you want to preserve per row inside "value" field.
[...]
Since JSF 2.1, UIData implementation has a new property called rowStatePreserved. Right now this property does not appear on facelets taglib documentation for h:dataTable, but on the javadoc for UIData there is. So the fix is very simple, just add rowStatePreserved="true" in your h:dataTable tag:
In the end, you have basically 3 options:
Use UIInput#value instead of something custom like MYDATA
As instructed by the abovementioned blog, just replace getMyData() and setMyData() by the existing getValue() and setValue() methods from UIInput. Your composite component already extends from it.
#Override
public void encodeBegin(FacesContext context) throws IOException {
this.setValue(calculateData()); // setValue instead of setMyData
super.encodeBegin(context);
}
#Override
public void processDecodes(FacesContext context) {
super.processDecodes(context);
LOG.log(Level.INFO, "myData {0}", getValue() ); // getValue instead of getMyData
}
And equivalently in the XHTML implementation (by the way, the <h:outputText> is unnecessary here):
<h:outputText value="#{cc.value}" /> <!-- cc.value instead of cc.myData -->
However, this didn't really work when I tried it on Mojarra 2.3.14. It turns out that Mojarra's implementation of the <ui:repeat> indeed restores the EditableValueHolder state during restore view (yay!), but then completely clears out it during decode (huh?), turning this a bit useless. I'm frankly not sure why it is doing that. I have also found in Mojarra's UIRepeat source code that it doesn't do that when it's nested in another UIData or UIRepeat. So the following little trick of putting it in another UIRepeat attempting to iterate over an empty string made it work:
<ui:repeat value="#{''}">
<ui:repeat value="#{myController.data}" var="s">
<my:myComponent data="#{s}" />
</ui:repeat>
</ui:repeat>
Remarkably is that nothing of this all worked in MyFaces 2.3.6. I haven't debugged it any further.
Replace <ui:repeat> by <h:dataTable rowStatePreserved="true">
As hinted in the abovementioned blog, this is indeed documented in UIData javadoc. Just replace <ui:repeat> by <h:dataTable> and explicitly set its rowStatePreserved attribute to true. You can just keep using your MYDATA attribute in the state.
<h:dataTable value="#{myController.data}" var="s" rowStatePreserved="true">
<h:column><my:myComponent data="#{s}" /></h:column>
</h:dataTable>
This worked for me in both Mojarra 2.3.14 and MyFaces 2.3.6.
This is unfortunately not supported on UIRepeat. So you'll have to live with a potentially unnecessary HTML <table> markup generated by the <h:dataTable>. It was during JSF 2.3 work however discussed once to add the functionality to UIRepeat, but unfortunately nothing was done before JSF 2.3 release.
Include getClientId() in state key
As suggested by Selaron in your question's comments, store the client ID along as key in the state.
public String getMyData() {
return (String) getStateHelper().get("MYDATA." + getClientId());
}
public void setMyData(String data) {
getStateHelper().put("MYDATA." + getClientId(), data);
}
Whilst it's a relatively trivial change, it's awkward. This does not infer portability at all. You'd have to hesitate and think twice every time you implement a new (composite) component property which should be saved in JSF state. You'd really expect JSF to automatically take care of this.
I have the following command button in the view with ID "save":
<p:panel style="border:none;text-align:left;margin:0;">
<p:commandButton value="Save Document" id="save" icon="fa fa-save"
disabled="#{dIGRCController.digrc.qconce == '020'}">
<f:param name="validate" value="true" />
</p:commandButton>
<p:commandButton value="Clear" icon="fa fa-undo"></p:commandButton>
</p:panel>
I am trying to dynamically assign a different actionListener. If the user wants to INSERT some new record, I want it to call the insert method. If the user wants to update an existing record, it should call the update method.
Right now I am trying to do this:
#PostConstruct
public void init() {
// setting the action listener of the Save Document button
UIViewRoot viewRoot = FacesContext.getCurrentInstance().getViewRoot();
// UIComponent button = viewRoot.findComponent("save");
CommandButton button = (CommandButton) viewRoot.findComponent("save");
FacesContext context = FacesContext.getCurrentInstance();
MethodExpression methodExpression = context
.getApplication()
.getExpressionFactory()
.createMethodExpression(context.getELContext(),
"#{dIGRCController.updateDocument}", null,
new Class[] { DIGRCController.class });
button.addActionListener(new MethodExpressionActionListener(
methodExpression));
}
I am getting a null pointer exception on the line:
button.addActionListener(new MethodExpressionActionListener(
methodExpression));
What am I doing wrong? Is there another way to accomplish what I am trying to do? I am using JSF 2.2, PrimeFaces 5.3 and OmniFaces 1.11.
The findComponent() takes a client ID as argument not a component ID. The client ID is exactly the value of the generated HTML id attribute associated with the component in question. In case of a command button, usually the component ID of the parent <h:form> is prepended, separated by the naming container separator character which defaults to :.
Given this,
<h:form id="form">
<p:commandButton id="save" ... />
</h:form>
the client ID would be form:save.
CommandButton button = (CommandButton) viewRoot.findComponent("form:save");
See also this related question as to identifying and using client ID: How to find out client ID of component for ajax update/render? Cannot find component with expression "foo" referenced from "bar"
Unrelated to the concrete problem, manipulating the component tree in Java side is a poor practice. You'd better keep using XHTML+XML for this which is so much more self-documenting as to declaring/defining tree structures. You can use JSTL tags to dynamically build the view (note: this is different from dynamically rendering the view using rendered attribute!).
E.g.
<p:commandButton ... action="#{bean.save}">
<c:if test="#{bean.existing}">
<f:actionListener binding="#{bean.needsUpdate()}" />
</c:if>
</p:commandButton>
See also JSTL in JSF2 Facelets... makes sense?
Even more, you could just pass #{bean.existing} as method argument.
<p:commandButton ... action="#{bean.save(bean.existing)}" />
Both approaches are in turn admittedly kind of weird if #{bean.existing} refers the same bean as #{bean.save}. You could just check for that inside #{bean.save} itself.
public void save() {
if (existing) {
// UPDATE
} else {
// INSERT
}
}
Going further on that, this is IMO not the responsibility of frontend layer, but of the service layer. You pass the whole entity to the service layer which in turn checks based on PK if it's existing or not.
if (entity.getId() == null) {
// INSERT
} else {
// UPDATE
}
I have read a lot of posts at Stackoverflow but I didn't succeed in implementing the belowmentioned problem from my side.
the problem is: I need to type some text in <p:inputTextarea> and when clicking on button I need to get this value in the bean method.
I.e.:
<p:inputTextarea binding="#{input}"/>
<p:commandButton action="#{pessoaMB.adicionarContato(input.value)}" immediate="true"/>
with the bean method:
public void adicionarContato(String value) {
System.out.println(value);
}
The code I'm using gives me a null value.
I'm using #ViewScoped and cannot change this.
First of all, a side note: it is a bad practice to work with JSF components, you should work with model instead. I.e. don't use binding="#{input}", but stick to value="#{bean.text}".
Second, I doubt that immediate="true" is used appropriately in your setup. When used in a UICommand component like <h:commandButton> it will cause to skip JSF lifecycle for components with immediate="false" (or omitted, as it's the default), thus their value won't be set at all. Still, JSF will still preset submittedValue behind the scenes before the action method is executed.
Also, I strongly recommend to read BalusC's blog post Debug JSF lifecycle, as it is more than enlightening on the topic.
As to the solution, I'd suggest to deal with value binding with the bean, as presented in the first comment. With this approach you won't need action method parameter at all. Moreover, rethink your use of immediate attribute. If you think it's correct then you've got two choices: (1) use immediate="true" on <p:inputTextarea> or (2) switch to action="#{bean.action(input.submittedValue)}".
I would've done this :
<h:form>
<p:inputText value="#{pessoaMB.input}"/>
<p:commandButton value="add" action="#{pessoaMB.adicionarContato}" />
</h:form>
input would be here a pessoaMB property with a getter and setter (an IDE can autogenerate it).
private String input;
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
As for the adicionarContato method, it would be like this :
public void adicionarContato() {
System.out.println(input);
}
You should create a new class, i.e:
public class MyFields(){
String input1;
String input2; //and so on...
//getters and setters
}
Then, in pessoaMB create a property:
private MyFields inputFields; //getter and setter
Finally, in your xhtml file:
<h:form>
<p:inputText value="#{pessoaMB.inputFields.input1}"/>
<p:inputText value="#{pessoaMB.inputFields.input2}"/>
<!-- add more inputText components... -->
<p:commandButton value="add" action="#{pessoaMB.adicionarContato}" />
</h:form>
I have a managed bean under ViewScope. It has an instance variable inside it.
MetaData object has a inputItem object List.
#ManagedBean
#ViewScoped
public class ConBean implements Serializable {
private MetaData metadata;
#PostConstruct
#SuppressWarnings("unchecked")
public void init() throws IOException {
this.metadata = new MetaData ();
}
public void proc(){
List<InputItem> inputs= new ArrayList<InputItem>();
inputs.add(***** code to populate the inputItem List);
//after populating, inputs added to the metadata
metadata.setInputs(inputs);
}
//getters & setters
}
in my JSF , input list is populated inside a UI repeat.
<div id="inputplaceholder">
<ui:repeat value="#{conBean.metaData.inputs}" var="content">
</ui:repeat>
</div>
the div inputplaceholder is periodically updated using a richfaces poll.
<a4j:poll id="poll" interval="12000" action="#{conBean.proc}"
execute="#form" render="inputplaceholder"/>
The problem that I have is even though inputItems are set to the metaData object correctly inside the proc() method, when the view is rendered/partially updated, it doesn't get highlighted in the UI. so partial update takes no effect. I tried moving
this.metadata = new MetaData ();
inside the proc method but had no luck.
any ideas and help is highly appreciated.
thanks ...
Did the partial render really take place? This is impossible. There is namely no JSF component with the ID inputplaceholder. You assigned it to a plain HTML <div> element. Replace it by a fullworthy JSF component:
<h:panelGroup layout="block" id="inputplaceholder">
Also, since you used a relative ID in the render attribute, it will only scan for components in the same parent naming container component. The <ui:repeat> is such one, however the component with the desired ID is placed outside it. You'd like to use an absolute ID instead. Assuming that it's inside a <h:form> with a fixed ID:
<h:form id="myform">
<h:panelGroup layout="block" id="inputplaceholder">
...
then you should be referencing it in the render attribute as follows
render=":myform:inputplaceholder"
I have a problem to bind list of h:selectBooleanCheckbox to my bean.
Anybody helps ?
This is not working:
<ui:repeat value="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox binding="#{cartBean.checkboxes[i.index]}" />
</ui:repeat>
public class CartBean extends BaseBean {
public List<Product> getProductsList() {...}
private HtmlSelectBooleanCheckbox[] checkboxes;
public HtmlSelectBooleanCheckbox[] getCheckboxes() {
return checkboxes;
}
public void setCheckboxes(HtmlSelectBooleanCheckbox[] checkboxes) {
this.checkboxes = checkboxes;
}
}
I get error:
javax.faces.FacesException: javax.el.PropertyNotFoundException: /WEB-INF/flows/main/cart.xhtml #26,97 binding="#{cartBean.checkboxes[i.index]}": Target Unreachable, 'checkboxes' returned null
I solved my problem. I used code like below and get what i want (thanks to BalusC blog - http://balusc.blogspot.com/2006/06/using-datatables.html#SelectMultipleRows):
<ui:repeat value="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox value="#{cartBean.selectedIds[cartProduct.id]}" />
</ui:repeat>
public class CartBean extends BaseBean {
private Map<Integer, Boolean> selectedIds = new HashMap<Integer, Boolean>();
public Map<Integer, Boolean> getSelectedIds() {
return selectedIds;
}
}
Your concrete problem is caused because the binding attribute is evaluated during view build time, that moment when the XHTML source code is turned into a JSF UI component tree, while the <ui:repeat> runs during view render time, that moment when the JSF UI component tree needs to produce HTML.
In other words, the #{i.index} is only available during view render time and evaluates as null during view build time. In effects, you're doing a binding="#{cartBean.checkboxes[null]}"
There's another conceptual mistake here: you seem to expect that the <ui:repeat> produces physically multiple <h:selectBooleanCheckbox> components. This is untrue. There's physically only one <h:selectBooleanCheckbox> which is reused multiple times to produce HTML based on the currently iterated variable. Actually, binding="#{cartBean.checkbox}" was been sufficient. However, collecting the values is a story apart. I won't go in detail, but you can find several hints in this answer: Validate order of items inside ui:repeat.
In order to achieve the (apparent) concrete functional requirement of generating physically multiple <h:selectBooleanCheckbox> components and binding each to a separate array item, you should be using an iteration component which runs during view build time instead of view render time. That's the JSTL <c:forEach>:
<c:forEach items="#{cartBean.productsList}" var="cartProduct" varStatus="i">
<h:selectBooleanCheckbox binding="#{cartBean.checkboxes[i.index]}" />
</c:forEach>
But, after all, using binding on a bean property should be avoided as much as possible. Use instead exactly that attribute which you ultimately need: the value attribute. This way you don't need to do a HtmlSelectBooleanCheckbox#getValue() everytime. You already figured the right solution with a Map<Integer, Boolean> selectedIds:
<ui:repeat value="#{cartBean.productsList}" var="cartProduct">
<h:selectBooleanCheckbox value="#{cartBean.selectedIds[cartProduct.id]}" />
</ui:repeat>
See also:
JSTL in JSF2 Facelets... makes sense?
I don't know if you can bind elements stored in an array. But in your code, the problem is that your HtmlSelectBooleanCheckbox[] is null. So maybe change your Java code to:
public HtmlSelectBooleanCheckbox[] getCheckboxes() {
if (checkboxes == null) {
checkboxes = new HtmlSelectBooleanCheckbox[getProductsList().size()];
}
return checkboxes;
}
but I am really not sure if it will work... Maybe the solution is to not bind your HtmlSelectBooleanCheckbox elements in the Java code. Why do you need to bind them?