Binding a Map to a DropDownChoice in Wicket App

One day i had to change a page (WebPage) in a way that it would allow me to persist a simple attribute of an entity. First i tried to use an Enum, however i’m using JPA persistence with Hibernate and was a little bit concerned about how Hibernate would deal with this Enum in searches or some other more advanced stuff. So i decided to create a simple Integer attribute and set a constant on it.

This is a sample of code using a Map to exhibit a list of options (DropDownChoice) in a Wicket application to persist a constant (Integer) in an entity.

Code of ControlSerum entity where the attribute status will be persisted:

@Entity
public class ControlSerum {
  private Integer status;

  public final static int STATUS_PREP = 0;
  public final static int STATUS_ACTIVE = 1;
  public final static int STATUS_INACTIVE = 2;
  private final static Map<Integer, String> statusMap = new HashMap<Integer, String>();

  static{
    statusMap.put(STATUS_PREP, "Em preparo");
    statusMap.put(STATUS_ACTIVE, "Ativo");
    statusMap.put(STATUS_INACTIVE, "Inativo");
  }

  @Column(nullable=false)
  public Integer getStatus() {
    return status;
  }
  public void setStatus(Integer status) {
    this.status = status;
  }

  @Transient
  public static Map<Integer, String> getStatusMap(){
    return new HashMap<Integer, String>(statusMap);
  }
}

At ControlSerumEditPage page class, i implemented a IChoiceRenderer to renderize correctly the options of select tag using the Map key as the value of option tag and the Map value as the name for exibition of option tag.

ControlSerumEditPage class constructor snippet where a renderizer for DropDownChoice is instantiated and added to Form:

IChoiceRenderer choicesRenderer = new IChoiceRenderer() {
  @Override
  public String getDisplayValue(Integer object) {
    return ControlSerum.getStatusMap().get(object);
  }
  @Override
  public String getIdValue(Integer object, int index) {
    return object.toString();
  }
};

IModel optionsModel = new Model(){
  @Override
  public Serializable getObject() {
    return new ArrayList(ControlSerum.getStatusMap().keySet());
  }
};

IModel statusModel = new PropertyModel<Integer>(controlSerum, "status");

DropDownChoice<Integer> status = new DropDownChoice<Integer>("status", statusModel, optionsModel, choicesRenderer);
form.add(status);

To download the full code of this application (still in development):
http://github.com/ziglee/biomedcalib

Please post your doubts or comments and i’ll promptly answer you!

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