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Posted to users@wicket.apache.org by tech7 <te...@gmail.com> on 2011/03/22 12:16:25 UTC

ListMultipleChoice Binding List Problem

Hi,
I have a problem constructing ListMultipleChoice objects inside the loop.
I had written the code as:
List	groupModelsDrop			= new ArrayList();
propertyLoop2 = new Loop("properties2", propertyList2.size()) {

			@Override
			protected void populateItem(final LoopItem propertyItem) {
				final Property property2 =
propertyList2.get(propertyItem.getIteration());
				propertyItem.add(new Label("propertyName2", property2.getName()));

				final List itemList2 = new ArrayList(property2.getItems());
				IModel&lt;Collection&lt;Item&gt;> allItemsModel = new
PropertyModel&lt;Collection&lt;Item&gt;>(	  new Model(),
																								
groupModelsDrop.get(propertyItem.getIteration())
);
				final ListMultipleChoice itemSelect = new ListMultipleChoice(
"itemList",
																				allItemsModel,
																				itemList2,
																				new IChoiceRenderer() {

																					@Override
																					public String getIdValue(Item item, int index) {
																						return String.valueOf(item.getId());
																					}

																					@Override
																					public String getDisplayValue(Item item) {
																						return item.getName();
																					}
																				}); 	
propertyItem.add(itemSelect);
			};
		};


but the problem is; when i submit the form it gives an error "WicketMessage:
Attempted to set property value on a null object. Property expression:
groupModelsDrop.get(propertyItem.getIteration()) " like that.
Where is my fault?
I need your suggestions.
With my best regards.

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Re: ListMultipleChoice Binding List Problem

Posted by Andrea Del Bene <ad...@ciseonweb.it>.
Hi tech7,

in these lines:

  IModel<Collection<Item>> allItemsModel = new 
PropertyModel<Collection<Item>>(  new Model(),
     groupModelsDrop.get(propertyItem.getIteration()));

you are building a property model from another generic model (i.e. new 
Model()) without an instance inside it. So when property model tries to 
resolve property expression, it gets a null reference.

> Hi,
> I have a problem constructing ListMultipleChoice objects inside the loop.
> I had written the code as:
> List	groupModelsDrop			= new ArrayList();
> propertyLoop2 = new Loop("properties2", propertyList2.size()) {
>
> 			@Override
> 			protected void populateItem(final LoopItem propertyItem) {
> 				final Property property2 =
> propertyList2.get(propertyItem.getIteration());
> 				propertyItem.add(new Label("propertyName2", property2.getName()));
>
> 				final List itemList2 = new ArrayList(property2.getItems());
> 				IModel&lt;Collection&lt;Item&gt;>  allItemsModel = new
> PropertyModel&lt;Collection&lt;Item&gt;>(	  new Model(),
> 																								
> groupModelsDrop.get(propertyItem.getIteration())
> );
> 				final ListMultipleChoice itemSelect = new ListMultipleChoice(
> "itemList",
> 																				allItemsModel,
> 																				itemList2,
> 																				new IChoiceRenderer() {
>
> 																					@Override
> 																					public String getIdValue(Item item, int index) {
> 																						return String.valueOf(item.getId());
> 																					}
>
> 																					@Override
> 																					public String getDisplayValue(Item item) {
> 																						return item.getName();
> 																					}
> 																				}); 	
> propertyItem.add(itemSelect);
> 			};
> 		};
>
>
> but the problem is; when i submit the form it gives an error "WicketMessage:
> Attempted to set property value on a null object. Property expression:
> groupModelsDrop.get(propertyItem.getIteration()) " like that.
> Where is my fault?
> I need your suggestions.
> With my best regards.
>
> -----
> Wicket-Java
> --
> View this message in context: http://apache-wicket.1842946.n4.nabble.com/ListMultipleChoice-Binding-List-Problem-tp3396083p3396083.html
> Sent from the Users forum mailing list archive at Nabble.com.
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@wicket.apache.org
> For additional commands, e-mail: users-help@wicket.apache.org
>
>
>


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