Inserting empty value to a combobox

[blackbox23]

Hello,

I really hope someone could help me out on this one. Been trying to figure this out for 3 days now.

I want to insert an empty value to a combo box drop down list. I did this by adding a modeldata with "&nbsp" as the displayfield. The drop down list displays correctly..(please see code 1/attachment 1). However when I select it, the combobox field also displays "&nbsp", so I added a ListModelPropertyEditor and overrode getStringValue, but it doesn't work, and. worse, the drop down list doesnt work too. (please see code2/attachment 2).

Here's my code:

code1:



final ComboBox<ModelData> combo = new ComboBox<ModelData>();
combo.setFieldLabel("test");
ListStore<ModelData> store = new ListStore<ModelData>();
combo.setStore(store);
combo.setDisplayField("display");
combo.setTriggerAction(TriggerAction.ALL);



ModelData m = new BaseModelData();
m.set("display", "&nbsp");
m.set("value", 1);
store.add(m);

m = new BaseModelData();
m.set("display", "2");
m.set("value", 2);
store.add(m);

fp.add(combo, new FormData("-20"));

code2:


final ComboBox<ModelData> combo = new ComboBox<ModelData>();
combo.setFieldLabel("test");
ListStore<ModelData> store = new ListStore<ModelData>();
combo.setStore(store);
combo.setDisplayField("display");
combo.setTriggerAction(TriggerAction.ALL);
combo.setPropertyEditor(new ListModelPropertyEditor<ModelData>() {
@Override
public String getStringValue(ModelData value) {
if (value.get("display").equals("&nbsp")) {
return "";
}
return (String) value.get("display");
}
});


ModelData m = new BaseModelData();
m.set("display", "&nbsp");
m.set("value", 1);
store.add(m);

m = new BaseModelData();
m.set("display", "2");
m.set("value", 2);
store.add(m);

fp.add(combo, new FormData("-20"));



I'm using GXT 2.1.1/GXT2.0. Please help me.


Thanks.

[sven]

You can for example change the template and add a height to the used markup. Another solution would be to use a ModelProcessor and fill a custom field with "&nbsp;" that gets displayed in the template.

In both ways you probably have to extend ComboBox and override getValue(), because that returns null if the raw value is an empty string.

[blackbox23]

Hi Sven,

i Really hate to say this. But I don't have an idea how to do just that. I'm not that familiar with using templates. Can you point me to an example on how to do just that?

Thank you

[sven]

http://www.sencha.com/examples/explorer.html#combobox
This example uses custom templats. Simple add a height to the markup, like 20px for example.

[blackbox23]

I just added a template without even setting the height and it worked:

private native String getTemplate() /*-{
return [
'<tpl for=".">',
'<div class="x-combo-list-item">{[values.display]}</div>',
'</tpl>'
].join("");
}-*/;

thanks a lot man.