calculate the rendering of a custom control - xpages

Question

In an xpage I would like to be able to decide which custom controls have to be rendered or loaded.
I have a custom control named 1, another 2, 3 etc
When a scoped variable has the value 1, custom control 1 should be displayed/rendered/loaded.
A value of 2 , custom control 2 has to be displayed. etc
I came up with following sollution :
I calculate if that custom control has to be loaded or not depending on the value of the scoped variable.
Since I have 8 of these custom controls on 1 page I was wondering ,since only 1 out of those 8 custom controls have to be rendered ,if there isn't a better way with less code to do the same job. Won't my sollution put a lot of load to my server ?

Answer 1

A better solution is to inject your custom control on the fly. This can be easily done with java:
package ch.hasselba.xpages;
import java.util.UUID;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import com.ibm.xsp.extlib.builder.ControlBuilder;
import com.ibm.xsp.extlib.builder.ControlBuilder.ControlImpl;
import com.ibm.xsp.component.UIIncludeComposite;
import com.ibm.xsp.context.FacesContextExImpl;
import com.ibm.xsp.util.FacesUtil;
public class XPagesUtil {
public void injectCC( final String ccName , final String componentName ){
FacesContextExImpl fc = (FacesContextExImpl) FacesContext.getCurrentInstance();
UIComponent cmp = FacesUtil.findChildComponent(fc.getViewRoot(), componentName );
UIIncludeComposite objCtrl = new UIIncludeComposite();
objCtrl.setPageName( ccName );
objCtrl.setId("new_" + UUID.randomUUID() );
ControlBuilder cBuilder = new ControlBuilder();
ControlImpl<UIIncludeComposite> objImplControl = new ControlImpl<UIIncludeComposite>(objCtrl);
ControlImpl<UIComponent> objImplParent = new ControlImpl<UIComponent>(cmp);
objImplParent.addChild(objImplControl);
cBuilder.buildControl(fc,objImplParent,false);
}
}
To use the code on your XPage, you now can do the following:
<?xml version="1.0" encoding="UTF-8"?>
<xp:view xmlns:xp="http://www.ibm.com/xsp/core">
<xp:this.afterPageLoad>
<![CDATA[#{javascript:
importPackage( ch.hasselba.xpages.extlib );
var nameOfCC = "/IncludeCC.xsp";
new ch.hasselba.xpages.XPagesUtil().injectCC(nameOfCC, "parent");
}]]>
</xp:this.afterPageLoad>
<xp:div id="parent" />
</xp:view>
You can now calculate the variable nameOfCC.

Answer 2

Sven's solution looks absolutely brilliant but also kinda scary at the same time. Though I'm definitely going to play with that.
There is a more "out of the box" possibility that might work for you. the Dynamic Content Control of the extension library. My understanding is that it's designed for exactly this. You still need to predefine your custom controls (unlike Sven's Java injection) but the dynamic content control is better performing then trying to control all the rendering manually. There's a demo in the ext. library demo app but heres a snippet I've used:
<xe:dynamicContent
id="dynamic">
<xp:this.facets>
<xp:panel
xp:key="cat">
<xc:cc_form_category></xc:cc_form_category>
</xp:panel>
<xp:panel
xp:key="subCategory">
<xc:cc_form_subCategory></xc:cc_form_subCategory>
</xp:panel>
<xp:panel
xp:key="rental">
<xc:cc_form_rentalID></xc:cc_form_rentalID>
</xp:panel>
<xp:panel
xp:key="default">default content</xp:panel>
</xp:this.facets>
</xe:dynamicContent>
That's basically the setup of the custom controls. then I've been using some Client Side JavaScript when I want to show one or make a change.
XSP.showContent("#{id:dynamic}","cat")
XSP.partialRefreshPost('#{id:mainPanel}', {})
I think if it kinda like a Switch Statement really.
Hope that helps.