Re: [Wicket-user] Newbie question: applying dynamic form component with ListView

Wed, 15 Mar 2006 09:44:05 -0800

Hi Michael,
 
One thing that I personally think is important to understanding ListView is knowing that each item in the ListView is one concrete model object instance.  If you think about it, then you will see you shouldn't need many(if any) collections in your form backing model classes.  So a ListView takes a 'list' of model objects and displays each one independent of the other.  One of the cool things about wicket is that your model object instance fields can be strongly typed (more easily than Struts). As you'll see in the model object below.  Take a look at the following code which is based on your example (I only used generics for type clarity):
 

public class DetailForm extends Form {
 private final List ageList = Arrays.asList(new Integer[] {
   Integer.valueOf(10), Integer.valueOf(20), Integer.valueOf(30) });
 
 // You'll probably want to pass your list in to your form constructor, as opposed to this.
 private final static List<DetailModel> model = initModelList();
 
 public DetailForm(final String id) {
 
  super(id);
 
  // This model is a list of DetailModels
  ListView listView = new ListView("detailList", model) {
 
   public void populateItem(final ListItem listItem) {
 
    listItem.setModel(new CompoundPropertyModel(
      (DetailModel) listItem.getModelObject()));
 
    // This is bound to model.getCode()/setCode()
    listItem.add(new TextField("code"));
 
    // Same for model.getAge()/setAge()
    listItem.add(new DropDownChoice("age", ageList));
 
    // Same for model.getName()/setName()
    listItem.add(new TextField("name"));
   }
  };
  add(listView);
 
 }
 
 // Just a test to see that your changes are taking effect.
 @Override
 protected void onSubmit() {
  System.out.println(model);
 }
 
// Again, not ideal, but for the sake of this example.
 private static List<DetailModel> initModelList() {
  List<DetailModel> model = new ArrayList<DetailModel>();
  model.add(new DetailModel(Integer.valueOf(10), "Harry", "bigboy"));
  model.add(new DetailModel(Integer.valueOf(20), "Jan", "foo"));
  model.add(new DetailModel(Integer.valueOf(30), "Meg", "boss"));
  return model;
 }
 
 public static class DetailModel implements Serializable {
 
  private Integer age;
  private String name;
  private String code;
 
  public DetailModel() {
 
  }
 
  public DetailModel(Integer age, String name, String code) {
   super();
   this.age = age;
   this.name = name;
   this.code = code;
  }
 
  public String getCode() {
   return code;
  }
 
  public void setCode(String code) {
   this.code = code;
  }
 
  public Integer getAge() {
   return age;
  }
 
  public void setAge(Integer age) {
   this.age = age;
  }
 
  public String getName() {
   return name;
  }
 
  public void setName(String name) {
   this.name = name;
  }
 
  @Override
  public String toString() {
   return name + ", " + age + "(" + code + ")";
  }
 }
 
}
Good luck, I hope this helps you understand.  Just remember that it really is as easy as it should be, which (sadly) takes some getting used to if you've used other frameworks.
----- Original Message -----
From: Michael K
Sent: Wednesday, March 15, 2006 4:22 AM
Subject: [Wicket-user] Newbie question: applying dynamic form component with ListView

Hi,

Which type should I define in POJO Model to hold the value of the array of TextField/DropDownChoice when populated by ListView? Should I define it as String[] or ArrayList or something else?

I have attached the following example to explain my situation:


    public class DetailForm extends Form {
        private java.util.List ageList = Arrays.asList(new String[]{ "10", "20", "30" });
        public DetailForm(String string){

            super(string);
            DetailModel dm = new DetailModel();

            setModel(new CompoundPropertyModel(dm));

            ListView listView = new ListView("detailList", new PropertyModel(this, "detailData")){

                public void populateItem(final ListItem listItem){
                    final String detail = (String) listItem.getModelObject();
                    listItem.add(new Label("code",detail));
                    listItem.add(new DropDownChoice("age",ageList));
                    listItem.add(new TextField("name"));
                }
            };
            add(listView);

        }

        public List getDetailData(){
            java.util.List hm = new ArrayList();

            // Should get the data from DB, for simplicity I use hardcode value
            hm.add("aaaa");
            hm.add("bbbb");
            hm.add("cccc");
            return hm;
        }
    }


      & nbsp; // Model class
    public class DetailModel implements Serializable {

        private String[] age = new ArrayList();   // ???? Not sure about the type
        private String[] name;

        public String[] getAge(){
            return age;
        }

        public void setAge(String[] age){
            this.age = age;
        }

        public String[] getName(){
            return name;
        }

        public void setName(String[] name){
            this.name = name;
        }
    }

The idea behind String[] was my 'past time' with Struts  :)
Any suggestion?


Cheers,

Michael

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