Author
Robert Wenzel, Engineer, Potix Corporation

Date
July/August 2015

Version
ZK 8.0

Introduction

In the previous Part 1 LINK ME I created a wizard template together with a model. I showed its usage in a trivial case. This Part will focus on reusing the same wizard template in a different scenario with more complex steps. I'll go deeper into templating and reuse various parts of the UI.

I'll also highlight some optional features to give the example more of a real life feeling.

Order Wizard (a more complex example)

As an example I chose a classical Shopping basket and Checkout process with the following steps:

Basket
adjust basket (add/remove/change items)
Shipping Address
enter shipping address
Payment
choose payment method + enter conditional details
Confirmation
review data, accept GTC submit order (handle exceptions)
Feedback
user feedback when order was successful

Order Model

The order model consists of straight forward java bean classes, to hold the data input during the order process. These classes are unaware of being used in inside a Wizard they simply provide getters and setters to hold/represent their state. (When looking into the code don't be confused by the validation annotations I'll talk about this topic in Part 3 LINK ME.)

Wizard/Step View Models

There are 3 view model classes representing our Ordering process. The OrderViewModel controls the overall wizard, initializes the steps and eventually the submits the final order. Two of the wizard steps require additional logic which is implemented in BasketViewModel(adding/removing basket items and display recommendations) and PaymentViewModel (handle payment method changes).

Creating the UI

The order.zul doesn't contain anything new.

<?component name="wizard" templateURI="/WEB-INF/zul/template/wizard/wizard.zul" ?>
<zk>
	<div width="500px" 
		 viewModel="@id('vm') @init('zk.example.order.OrderViewModel')" 
		 validationMessages="@id('vmsgs')"
		 onBookmarkChange="@command('gotoStep', stepId=event.bookmark)">
		 
		<wizard wizardModel="@init(vm.wizardModel)" order="@init(vm.order)"/>
	</div>
</zk>

More interesting are the individual step pages.

step 2-4 basket.zul

I'll start with the simpler steps for inputting the order information, as they share some common layout. They all consist of a simple row based layout: one row for each input field.

/src/main/webapp/WEB-INF/zul/order/steps/shippingAddress.zul: plain input form no addtional viewmodel required

<?taglib uri="/WEB-INF/tld/i18n.tld" prefix="i18n"?>
<?component name="formRow" templateURI="/WEB-INF/zul/template/wizard/formRow.zul" ?>
<zk xmlns:sh="shadow">
	<grid>
		<rows>
			<formRow type="static" label="@init(i18n:nls('order.basket'))" value="@init(order.basket)"/> 
		</rows>
	</grid>		
	${i18n:nls('order.shippingAddress.hint')}
	<grid>
		<rows>
			<formRow type="textbox" label="@init(i18n:nls('order.shippingAddress.street'))" 
				value="@ref(order.shippingAddress.street)"/> 
			<formRow type="textbox" label="@init(i18n:nls('order.shippingAddress.city'))" 
				value="@ref(order.shippingAddress.city)"/> 
			<formRow type="textbox" label="@init(i18n:nls('order.shippingAddress.zipCode'))" 
				value="@ref(order.shippingAddress.zipCode)"/>
		</rows>
	</grid>
</zk>

Line 6: Note: the value passed in statically using @init
Lines 13, 15, 17: Note: the value is bound by reference using @ref

/src/main/webapp/WEB-INF/zul/order/steps/shippingAddress.zul: plain input form no addtional viewmodel required

<?taglib uri="/WEB-INF/tld/i18n.tld" prefix="i18n"?>
<?component name="formRow" templateURI="/WEB-INF/zul/template/wizard/formRow.zul" ?>
<zk xmlns:sh="shadow" xmlns:ca="client/attribute">
	<grid>
		<rows>
			<formRow type="static" label="@init(i18n:nls('order.basket'))" value="@init(order.basket)"/> 
			<formRow type="static" label="@init(i18n:nls('order.shippingAddress'))" value="@init(order.shippingAddress)"/> 
		</rows>
	</grid>		
	${i18n:nls('order.payment.hint')}
	<grid viewModel="@id('paymentVM') @init('zk.example.order.PaymentViewModel', payment=order.payment)"
			payment="@ref(order.payment)">
		<rows>
			<formRow type="selectbox" label="@init(i18n:nls('order.payment.method'))" value="@ref(payment.method)"
					model="@init(paymentVM.availablePaymentMethods)"  
					updateCommand="@init(paymentVM.paymentMethodUpdateCommand)"/>
			
			<sh:if test="@load(paymentVM.hasCreditCard)">
				<formRow type="selectbox" label="@init(i18n:nls('order.payment.creditCard.type'))" 
						value="@ref(payment.creditCard.type)"
						model="@init(paymentVM.availableCreditCards)" />
				<formRow type="creditcard" label="@init(i18n:nls('order.payment.creditCard.number'))" 
						value="@ref(payment.creditCard.number)" />
				<formRow type="textbox" label="@init(i18n:nls('order.payment.creditCard.owner'))" 
						value="@ref(payment.creditCard.owner)" /> 
			</sh:if>
			
			<sh:if test="@load(paymentVM.hasBankAccount)">
				<formRow type="textbox" label="@init(i18n:nls('order.payment.bankAccount.iban'))" 
						value="@ref(payment.bankAccount.iban)" /> 
				<formRow type="textbox" label="@init(i18n:nls('order.payment.bankAccount.bic'))" 
						value="@ref(payment.bankAccount.bic)" /> 
			</sh:if> 
		</rows>
	</grid>

	<template name="creditcard">
		<textbox value="@bind(value)" ca:data-mask="${i18n:nls('order.creditCard.number.format')}"/>
	</template>
</zk>

Lines 18, 28: conditional inputs
Line 15: using model to render the selectbox
Line 16: passing in a viewmodel command via updateCommand to be notified of value changes
Lines 22, 37: injecting a custom template/type, to render a special input using an input mask

Every row is rendered using the same formRow template.

Form Row template

The core of this example is the formRow template which renders a form field based on the parameters type, label, value (and some conditional parameters). It uses several shadow components to achieve dynamic row rendering. It tries to reuse as much layout per row as possible (we'll enhance this template with validation messages in PART 3 LINK ME). The templates for input elements require additional template parameters such as model (used for selectbox) and updateCommand.

<zk xmlns:sh="shadow">
	<row>
		<sh:choose>
			<sh:when test="@init(type eq 'checkbox')">
				<cell/>
			</sh:when>
			<sh:otherwise>
				<label value="@init(label)"/>
			</sh:otherwise>
		</sh:choose>
		<sh:apply template="@init(type)"/>
	</row>
	
	<template name="checkbox">
		<checkbox checked="@bind(value)" onCheck="@command(updateCommand)" label="@load(label)"/>
	</template>
	
	<template name="textbox">
		<textbox value="@bind(value)" onChange="@command(changeCommand)"/>
	</template>

	<template name="selectbox">
		<selectbox selectedItem="@bind(value)" model="@load(model)" onSelect="@command(updateCommand)">
			<template name="model">
				<label value="@init(i18n:nls(each))"/>
			</template>
		</selectbox>
	</template>

	<template name="static">
		<label value="@load(value)" />
	</template>
	
	<template name="static-bookmark-link">
		<a label="@load(value)" href="@init(('#' += bookmark))"/>
	</template>
</zk>

Lines 15, 19, 23: binds the value passed in via @ref from the outside

step 1 basket.zul

/src/main/webapp/WEB-INF/zul/order/steps/basket.zul: the basket-step renders the basket items in a grid - nothing special about it, hence the abbreviated source.

<?taglib uri="/WEB-INF/tld/i18n.tld" prefix="i18n"?>
<zk xmlns:sh="shadow" xmlns:x="xhtml" >
	<div viewModel="@id('basketVM') @init('zk.example.order.BasketViewModel', basket=order.basket)">
		...
		${i18n:nls('order.basket.hint')}
		<grid model="@init(basketVM.itemsModel)">
			...
				<div>
					<sh:apply template="basketItemLabel" item="@init(item)"/>
					<a iconSclass="z-icon-times" sclass="red" onClick="@command('removeItem', basketItem=item)" tooltiptext="remove"/>
				</div>
			...
		</grid>
		
		<sh:if test="@load(basketVM.hasRecommendations)">
			<vlayout>
				${i18n:nls('order.basket.recommendation')}
				<sh:forEach items="@init(basketVM.recommendedItemsModel)">
					<div sclass="recommendation" onClick="@command('addRecommendedItem', item=each)" tooltiptext="add to basket">
						<sh:apply template="basketItemLabel" item="@init(each)"/>
						<a iconSclass="z-icon-plus green" href="#" />
					</div>
				</sh:forEach>
			</vlayout>
		</sh:if>

		<template name="basketItemLabel">
			<label value="@load(item.label)"/>
			<label value="@load(item.unitPrice) @converter(basketVM.priceFormatterParentheses)"/>
		</template>
	</div>
</zk>

Lines 9, 20, 27: a simple way to use a basketItemLabel-template in 2 places
Line 18: using <sh:forEach> bound to a ListModelList

At the bottom some of the new shadow elements (if, foreach, apply) are used to dynamically display the recommendations based on the current basket contents. Especially powerful is the combination of forEach/ListModelList. It will automatically expand/shrink/rearrange whenever the ListModelList (recommendedItemsModel) is changed.

Here a sample of what required for this in the view model:

public class BasketViewModel {

	//in the real life application injected using @WireVariable
	private RecommendationService recommendationService = new RecommendationService();
	
	private Basket basket;
	private ListModelList<BasketItem> basketItemsModel;
	private ListModelList<BasketItem> recommendedItemsModel;

	...

	@Command("addRecommendedItem")
	public void addRecommendedItem(@BindingParam("item") BasketItem item) {
		basketItemsModel.add(item);
		BindUtils.postNotifyChange(null, null, basket, "totalPrice");
		loadRecommendations();
	}
	
	...

	private void loadRecommendations() {
		recommendedItemsModel.clear();
		recommendedItemsModel.addAll(recommendationService.chooseRecommendations(this.basket));
		BindUtils.postNotifyChange(null, null, this, "hasRecommendations");
	}
	...

Line 8: the view model holds a ListModelList to contain the basket recommendations
Line 16: whenever the basket is updated (e.g. an item is added) reload the recommendations
Line 23: by changing the contents of the ListModelList the bound forEach element does it's job automatically

(it is not necessary to clear and replace all items - forEach can also handle single item additions/removals/movements, and will only reflect those changes in the component tree to reduce the overhead. This example simply illustrates, that it happens automatically, no additional notifyChange on the ListModel is required to update the recommendationList).

Additional features

As in a real application there are always requirements that somehow distract from the core solution, I just picked a few to show they don't necessarily break the overall design.

Input Mask

The payment.zul page uses an input mask to format the credit card number during user input. These kind of client side 'effects' can now be applied easily with custom data-handlers (a new ZK 8 Feature).

<template name="creditcard">
    <textbox value="@bind(value)" ca:data-mask="${i18n:nls('order.creditCard.number.format')}"/>
</template>

In the zk.xml the handler is configured as follows, it is loading an external jquery plugin (on demand, can be any JS resource), and decorates the widget with the JS code during initialization on the client side, the server side component behaves as usual, the view model isn't even aware of that.

		<data-handler>
			<name>mask</name><!-- the attribute name, i.e. data-mask -->
			<depends>http://igorescobar.github.io/jQuery-Mask-Plugin/js/jquery.mask.min.js</depends>
			<script>
				function (wgt, dataValue) {
					jq(wgt.$n()).mask(dataValue);
					wgt.listen({
						onChange: function (event) {
							event.data.value = jq(this.$n()).cleanVal();
						}
					});
				}
			</script>
		</data-handler>

Bookmarks Handling

A simple bookmarking mechanism is added to enable browser back navigation without leaving the wizard, nothing new but often forgotten while very simple to implement.

/wizardexample/src/main/webapp/order.zul: when a bookmark change is detected send the 'gotoPage' command

<?component name="wizard" templateURI="/WEB-INF/zul/template/wizard/wizard.zul" ?>
<zk>
	<div width="500px" 
		 viewModel="@id('vm') @init('zk.example.order.OrderViewModel')" 
		 validationMessages="@id('vmsgs')"
		 onBookmarkChange="@command('gotoStep', stepId=event.bookmark)">
		 
		<wizard wizardModel="@init(vm.wizardModel)" order="@init(vm.order)"/>
	</div>
</zk>

zk.example.order.OrderViewModel: whenever the wizard step changes set a bookmark, and vice versa, goto a step when the bookmark changes

		wizardModel = new WizardViewModel<WizardStep>(availableSteps) {
			@Override
			protected void onStepChanged(WizardStep currentStep) {
				bookmark.set(currentStep.getId(), false);
			}
		};
	...
	@Command("gotoStep")
	public void gotoStep(@BindingParam("stepId") String stepId) {
		if(!getWizardModel().gotoStep(stepId)) {
			//if step change unsuccessful override the bookmark
			bookmark.set(wizardModel.getCurrentStep().getId(), true);
		};
	}

zk.example.wizard.Bookmark: for completeness the trivial Bookmark class

public class Bookmark {
	public void set(String currentStepId, boolean replaceBookmark) {
		Executions.getCurrent().getDesktop().setBookmark(currentStepId, replaceBookmark);
	}
}

Custom I18N

To enable I18N the labels have been defined in the zk-label.properties and a custom mechanism is put place to conveniently convert enumerations to labels, icons or styles, in the same way as resolving plain simple labels.

/wizardexample/src/main/webapp/WEB-INF/zk-label.properties: defines the labels, enables adding localized versions e.g. zk-label_de.properties

zk.example.i18n.NlsFunctions: a set of I18n functions used throughout the application, both in zul and java code

Used via custom taglib functions in a zul file:

<?taglib uri="/WEB-INF/tld/i18n.tld" prefix="i18n"?>
	...
	${i18n:nls('order.shippingAddress.hint')}
	...
	<formRow type="static" label="@init(i18n:nls('order.basket'))" value="@init(order.basket)"/> 
	...

Called directly in java code:

		DecimalFormat decimalFormat = new DecimalFormat(NlsFunctions.nls("order.price.format"));
		return NlsFunctions.nlsArgs("order.basket.format", getTotalItems(), decimalFormat.format(getTotalPrice()));

Download

The source code for this article can be found in github.

Running the Example

The example consists of a maven web application project. It can be launched with the following command:

   mvn jetty:run

Then access the overview page http://localhost:8080/wizardexample/order.zul

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