JSF selectManyCheckbox

Question

Hello!

I'm having a hard time with a selectManyCheckbox. Basically what I am doing is loading a List of Categories in a selectManyCheckbox type controller (have done this either with a List or with a List with convertEntity). My problem is with the selected elements (value="#{cardListProvider.categoriesHolder.selectedCategories}"). After some reading I understand it also has to be a List, but what kind? And how can I set the selected categories? I'm not saving them in DB but I need to run some action in the bean with them!

Here's what I have:

    <h:selectManyCheckbox id="supportCategoryCardFilter"
value="#{cardListProvider.categoriesHolder.selectedCategories}" styleClass="greyText" required="false" >

             <s:selectItems var="filterList" value="#{cardListProvider.categoriesList}" label="#{filterList.label}" />

             <a:support id="supportCategoryCardFilter2" event="onchange"
reRender="someHolder, categoriesPanel" eventsQueue="onchange" action="#{cardListProvider.findCards(cardListProvider.categoriesHolder.selectedCategories)}" />

    </h:selectManyCheckbox>

I have wasted several hours with this... Can anyone help me? Thank you

Answer 1

You can bind to a String[] array like so:

public class CheckSelector {
  private String[] chosen;

  public String[] getChosen() { return chosen; }
  public void setChosen(String[] chosen) { this.chosen = chosen; }

  public SelectItem[] getChoices() {
    return new SelectItem[] { new SelectItem("1"), new SelectItem("2"),
        new SelectItem("3") };
  }
}

The value of the selectManyCheckbox should be bound to chosen. Alternatively, you can use a List:

public class CheckSelector {
  private List<String> chosen;

  public List<String> getChosen() { return chosen; }

  public void setChosen(List<String> chosen) { this.chosen = chosen; }

  public List<SelectItem> getChoices() {
    return Arrays.asList(new SelectItem("1"), new SelectItem("2"),
        new SelectItem("3"));
  }
}

The exact rules for value support are listed in the javadoc:

• If the component has an attached Converter, use it.
• If not, look for a ValueExpression for value (if any). The ValueExpression must point to something that is:
  • An array of primitives (such as int[]). Look up the registered by-class Converter for this primitive type.
  • An array of objects (such as Integer[] or String[]). Look up the registered by-class Converter for the underlying element type.
  • A java.util.List. Assume that the element type is java.lang.String, so no conversion is required.
• If for any reason a Converter cannot be found, assume the type to be a String array.

Answer 2

I see you are using Seam so no need to use Strings or any primitive type, you can bind directly to List. You just have to add another tag inside your selectManyCheckbox component which is and it will automatically do everything.

Better than doing all by yourself, check Seam documentation

http://docs.jboss.org/seam/2.2.0.GA/reference/en-US/html/controls.html#d0e28378