Posts Tagged ‘selectOneRadio

21
May
11

Enum backed h:selectOneRadio and h:selectOneMenu

Recently I needed to display a h:selectOneRadio and a h:selectOneMenu with values provided by a Java Enum. After some research on seamframework forum I saw one post that clarified a lot the way I should pursue, specially Pete’s comment. My greatest concern was the same of Pete: wiring up presentation and domain layer. But, after some analysis I found a simple solution that does not wire up domain and presentation layer and also respects the DRY principle. The solution involved crafting a class that would be instantiated as a Seam component on components.xml so it can be instantiated for each and every enum that we want to provide on view layer and also used EnumSet.allOf method so we could automagically iterate for each of the enum values.

Below, you can find the EnumList class:

/**
EnumList Seam Component - Converts Java Enums to List.
Copyright (C) 2011 Rafael Ribeiro

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
*/
import java.util.ArrayList;
import java.util.EnumSet;
import java.util.List;

import org.apache.commons.lang.builder.ToStringBuilder;
import org.apache.commons.lang.builder.ToStringStyle;

public class EnumList<T extends Enum<T>> {
private List<T> list;

public void setEnumClass(Class<T> c) {
list = new ArrayList<T>();
list.addAll(EnumSet.allOf(c));
}

public List<T> getList() {
return list;
}

public String toString() {
return new ToStringBuilder(this, ToStringStyle.SHORT_PREFIX_STYLE)
.append("list", list).toString();

}
}

And the configure it on components.xml as follows:

<component name="myEnumComp" scope="application" auto-create="true">
<property name="enumClass">br.com.rafaelri.MyEnum</property>
</component>
<factory name="myEnum" value="#{myEnumComp.list}" scope="application" auto-create="true"/>

Finally you’ll refer to it on your xhtml as follows:

<h:selectOneMenu id="myEnumSelect" value="#{instanceHome.instance.myEnum}">
<s:selectItems var="enum" value="#{myEnum}" label="#{enum.description()}"/>
<s:convertEnum />
</h:selectOneMenu>





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