Thursday, June 24, 2010

JSF composite component

On my latest project we used RichFaces as a component library. Our client didn't like to fill out the time with the RichFaces calendar. They wanted two combo boxes to fill out the time. I don't think this is the most user friendly way to solve picking a time (I like this timepicker) but our customer is king.

I thought that there would be someone on the internet who already created a component like that, but I could not find any so I made my own. JSF 2 will introduce a new component creation method. It will be simpler to create components and you do not have to write java code to make them work. But until we have JSF 2 available on all major application servers we will have to program some java for our components to work.

The plan I had for creating it was simple enough just take two HtmlSelectOneMenu components and fill them with default options.

So I ended with something like this:

private void createChildComponents(FacesContext context) {
Application application = context.getApplication();
hourInput = (HtmlSelectOneMenu) application.createComponent(HtmlSelectOneMenu.COMPONENT_TYPE);
minuteInput = (HtmlSelectOneMenu) application.createComponent(HtmlSelectOneMenu.COMPONENT_TYPE);
List<UIComponent> children = getChildren();
HtmlOutputText sparator = (HtmlOutputText) application.createComponent(HtmlOutputText.COMPONENT_TYPE);

UISelectItems hourItems = createSelectItems(application, 24, 1);

UISelectItems minuteItems = createSelectItems(application, 60, 5);

private UISelectItems createSelectItems(Application application, int number, int step) throws FacesException {
UISelectItems selectItems = (UISelectItems) application.createComponent(UISelectItems.COMPONENT_TYPE);
List<SelectItem> items = new ArrayList<SelectItem>();
for (int i = 0; i < number; i += step) {
items.add(new SelectItem(StringUtils.leftPad(String.valueOf(i), 2, "0")));
return selectItems;

Rendering this was not hard but to extract the selected value and store the submitted value back into the value binding, that was not so easy. First I tried to override the validate method but that didn't "sound" right, doing it in the updateModel was much better.

The only weird thing I was still facing was that, sometimes the value from the hour and minute components were converted to Integer but sometimes they where not. So I ended up with this construction to ensure that they were always Integer.

public void updateModel(FacesContext context) {


ValueExpression valueExpression = getValueExpression("value");
Date value = (Date) valueExpression.getValue(context.getELContext());
if (value != null && hourInput.getValue() != null
&& minuteInput.getValue() != null) {
Calendar calendar = Calendar.getInstance();
Integer hour = Integer.valueOf(hourInput.getValue().toString());
calendar.set(Calendar.HOUR_OF_DAY, hour);
Integer minute = Integer.valueOf((minuteInput.getValue().toString()));
calendar.set(Calendar.MINUTE, minute);

valueExpression.setValue(context.getELContext(), calendar.getTime());

Here I'm using the Java Date API. That of course is extremely sadistic so we could change it to use joda-time.

Now to use it we first register it as a component in components.taglib.xml

usage: <ctp:timepicker value="date"/>

Then make sure you have the components.taglib.xml registered in you're web.xml


And here an example of use, fist add the namespace on the top of you're page:


Then in our page you can do something like:

<ctp:timepicker value="#{catering.deliveryTime}"/>

Maybe this is not the best solution, if you have comments or tips, feel free drop them directly on this post. I'm interested in what you have to say!

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