How to create BINDING of command link with backing bean

[ram gaurav]

Hi

How to create BINDING of command link with backing bean

Thanks

[Bauke Scholtz]

h:commandLink is an UICommand � HtmlCommandLink component. Check the API doc.

[Richard Blaha]

Okay. A few days have passed since that advice was given. I am working with JSF and Java 1.6.0_14 using Netbeans 6.7.1. I am building my HtmlPanelGrid dynamically in the following way.

public void addItemNumbers(ValueChangeEvent changeEvent)
{
FacesContext facesContext = FacesContext.getCurrentInstance();
Application application =
facesContext.getApplication();
List<UIComponent> children = itemPanel.getChildren();
children.clear();
srchDesc= "";
srchItemno = (String)changeEvent.getNewValue();
String[][] itemArray = getItemsByItemno( srchItemno);

HtmlCommandLink outputItemno;
UIParameter id;

for ( int count = 0; count < itemArray.length; count++)
{
// ID REQUIRED
id = new UIParameter();
id.setName("id" + itemArray[count][0]);
id.setValue( itemArray[count][0]);
// ITEM NUMBER
outputItemno = (HtmlCommandLink) application.createComponent( HtmlCommandLink.COMPONENT_TYPE);
outputItemno.setValue( itemArray[count][0]);
String action = "#{ itemcountbean.listSetup}";
MethodExpression methodExpression =
FacesContext.getCurrentInstance().getApplication().getExpressionFactory().
createMethodExpression(FacesContext.getCurrentInstance().getELContext(), action, String.class,
new Class<?>[0]);
outputItemno.setActionExpression( methodExpression);
ValueExpression valueEx =
application.getExpressionFactory().createValueExpression(facesContext. getELContext(),
"#{itemcountbean.itemno}", String.class);
outputItemno.setValueExpression( itemArray[count][0], valueEx );
outputItemno.setStyle( "color: blue");
outputItemno.getChildren().add(id);
children.add( outputItemno);

// ITEM DESCRIPTION
HtmlOutputText outputItemDesc = (HtmlOutputText) application
.createComponent( HtmlOutputText.COMPONENT_TYPE);
outputItemDesc.setValue( itemArray[count][1]);
outputItemDesc.setStyle( "color: blue");
outputItemDesc.getChildren().add(id);
children.add( outputItemDesc);
}
logger.log( Level.FINER, "HtmlCommandLink item panel populated");
}


This is displayed by the JSP page with the following code:

<h:panelGrid id="itemPanel"
binding="#{ item.itemPanel}"
columns="2" border="1" cellspacing="5" />

The itemcountbean has the following coding in itemcountbean:

public String listSetup() {
logger.log( Level.INFO, "itemcountbean.listSetup");
logger.log( Level.INFO, "itemcountbean.itemno ["+this.itemno+"]");
...
return "itemcount_list";
}

Everything appears to be working except transferring via the 'binding' that is suppose to occur using the

ValueExpression valueEx =
application.getExpressionFactory().createValueExpression(facesContext. getELContext(),
"#{itemcountbean.itemno}", String.class);
outputItemno.setValueExpression( itemArray[count][0], valueEx );

part of the code.

And my
logger.log( Level.INFO, "itemcountbean.listSetup");
logger.log( Level.INFO, "itemcountbean.itemno ["+this.itemno+"]");

log returns

itemcountbean.listSetup
itemcountbean.itemno [null]

I have read through the JavaDocs to attempt to understand establishing the binding of ' #{itemcountbean.itemno} ' in the correct manner. I have searched dozens of sites trying to determine my error(s). Some advice was as little as 'Read the JavaDocs', but most was on binding before the JSF and/or NBs requiring use of the ValueExpression and setValueExpression. Most of the answers are 2-3 years old.

Would someone please help me in completion of binding/transferring my value from my HtmlCommandLink to be used in the backing bean?

Thank you.
rdb

[Richard Blaha]

OK. Here is what I found and what works. This is complete replacement code for what I presented in the previous post. This code is simpler and easier once I learned how to do it. I learned there is a huge difference between the introductory JSF code in chapter 1 and the Integrating of Data Grids in chapter 10 of JavaServerFaces In Action (Manning C 2005). Even in reading and using these examples (the first got me facing the problem I did and the second suggested I change my method) it still did not answer the question I needed answered. I ended up copying from a previous Visual ICEFaces project I had succesfully built. The final and key answer to my question I got from a blog I found searching for 'HtmlOutputText binding'. Passing component attributes from JSF to backing beans Again I have implemented all in the following replacement code.

itembean:

private String itemDataTableArray[][];


public void addItemNumbers(ValueChangeEvent changeEvent)
{
srchDesc= "";
srchItemno = (String)changeEvent.getNewValue();
itemDataTableArray = getItemsByItemno( srchItemno);
}

...

private HtmlDataTable itemDataTable = new HtmlDataTable();

public HtmlDataTable getItemDataTable() {
return itemDataTable;
}

public void setItemDataTable(HtmlDataTable hdt) {
this.itemDataTable = hdt;
}

private UIColumn column1 = new UIColumn();

public UIColumn getColumn1() {
return column1;
}

public void setColumn1(UIColumn uic) {
this.column1 = uic;
}
private UIColumn column2 = new UIColumn();

public UIColumn getColumn2() {
return column2;
}

public void setColumn2(UIColumn uic) {
this.column2 = uic;
}



This is displayed by the JSP page with the following code:


<h:dataTable id="itemDataTable" var="currentRow" styleClass="list_form" rowClasses="odd_row, even_row" border="1" cellspacing="5" binding="#{itembean.itemDataTable}" value="#{itembean.itemDataTableArray}">
<h:column binding="#{itembean.column1}" id="column1">
<f:facet name="header">
<hutputText value="Item Number" />
</f:facet>
<h:commandLink action="#{itemcountbean.listSetup}">
<hutputText id="outputText1" binding="#{itemcountbean.itemnoHtmlOutputText}" value="#{currentRow[0]}" >
<f:attribute name="itemText" value="#{currentRow[0]}" />
</hutputText>
</h:commandLink>
</h:column>
<h:column binding="#{itembean.column2}" id="column2">
<f:facet name="header">
<hutputText value="Item Desc" />
</f:facet>
<hutputText id="outputText2" value="#{currentRow[1]}" />
</h:column>
</h:dataTable>



The itemcountbean has the following coding in itemcountbean:

private String item = null;
private HtmlOutputText itemHtmlOutputText;

...

/**
* @return the itemHtmlOutputText
*/
public HtmlOutputText getItemHtmlOutputText() {
return itemHtmlOutputText;
}

/**
* @return the itemHtmlOutputText
*/
public String getItemHtmlOutputTextValue() {
return (String) itemHtmlOutputText.getAttributes().get("itemText");
}

/**
* @param itemHtmlOutputText the itemHtmlOutputText to set
*/
public void setitemHtmlOutputText(HtmlOutputText itemHtmlOutputText) {
this.itemHtmlOutputText = itemHtmlOutputText;
}


// Setup methods
public String listSetup() {
item = getItemHtmlOutputTextValue();
return "itemcount_itemlist";
}