Abid,
Hi,
I noted that you are adding the panel whether the data is null or not. I
would suggest you do this;
Data data = dataDao.getData(id)
if (data!= null){
//construct and add the panel
DataPanel panel = new DataPanel("panel", data);
add(panel);
//the panel has implementation of what to do with the data once it is
passed to it.
} else {
//forget about the panel and only add the label that says there is no
data
add(new Label("No data to display"));
}
regards
Josh
On Tue, Jul 27, 2010 at 11:48 AM, Josh Kamau <[email protected]> wrote:
> Abid,
>
> Hi,
>
> I noted that you are adding the panel whether the data is null or not. I
> would suggest you do this;
>
> if (data!= null){
>
> //construct and add the panel
>
>
> }
>
> On Tue, Jul 27, 2010 at 11:28 AM, Abid K <[email protected]> wrote:
>
>> I hope someone can help a newbie who is learning Wicket.
>>
>> I have the following code which accepts a parameter and then does a
>> database
>> query to get the 'Data' object. If the user enters the wrong Id the
>> database
>> query will return null and in this case I want to notify the user the data
>> could not be found and any other component should be hidden.
>>
>> But, when I get an null object the code stops working and a null exception
>> is thrown, any ideas? Or is there a elegant way to do this?
>>
>> public class DataView extends WebPage {
>>
>> private Data data;
>>
>> public DataView(PageParameters parameters) {
>> long dataId = parameters.getLong("dataId");
>>
>> DataDao dataDao = new DataDao();
>> data = dataDao.getData( dataId );
>>
>> // display message that the data could not be found
>> Label dataNotFound = new Label("dataNotFound", "Data could not be
>> found");
>> dataNotFound.setVisible(data == null);
>>
>> // otherwise display the panel containing the data
>> SomePanel panel = new SomePanel("somePanel");
>> panel.setVisible(data != null);
>>
>> add(dataNotFound);
>> add(panel);
>> }
>>
>> public class SomePanel extends Panel {
>> public SomePanel(String id) {
>> super(id);
>> // this throws null exception when data is null
>> Label label = new Label("someLabel", String.valueOf(data.getId()));
>> add(label);
>> }
>> }
>> }
>>
>> Thanks
>>
>
>
