GWT - Can you nest FormPanels inside FormPanels? - gwt

Question

I'm trying to nest a FormPanel inside another FormPanel. It seems that any field in the nested panel is never rendered.
This screenshot is produced by the code below it:
TabItem tabItem = new TabItem("Tab Item");
FormPanel formPanel = new FormPanel();
formPanel.setHeading("Form Panel");
formPanel.setFrame(true);
TextField textField = new TextField();
textField.setFieldLabel("Text Field");
FormPanel nestedPanel = new FormPanel();
nestedPanel.setHeading("Nested Panel");
TextField nestedField = new TextField();
nestedField.setFieldLabel("Nested Field");
nestedPanel.add(nestedField);
TextField anotherField = new TextField();
anotherField.setFieldLabel("Another Field");
formPanel.add(textField);
formPanel.add(nestedPanel);
formPanel.add(anotherField);
tabItem.add(formPanel);
tabPanel.add(tabItem);
Can anyone explain why the nested field does not show in the nested panel?
I've also tried using a CaptionPanel instead of a FormPanel as the nested panel, but the caption panel does not show the field label.
Any suggestions as to how I can get this to work would be most welcome. Thank you :)

Answer 1

As Jason mentioned, <form> cannot be nested. The GXT FormPanel draws a form as part of how it works, so consider drawing this layout in another way.
To emulate the appearance of the FormPanel, there are two basic steps.
To get the header, border, create a ContentPanel, and add the content to that
To get the GXT 2 layout of drawing the field labels, use a FormLayout in the content panel.
This will look something like this (from your example)
//...
ContentPanel nestedPanel = new ContentPanel(new FormLayout();
nestedPanel.setHeading("Nested Panel");
TextField nestedField = new TextField();
nestedField.setFieldLabel("Nested Field");
nestedPanel.add(nestedField);
//...
The outer field will still manage any binding, and the nested field will look as if they were in a FormPanel. If not using other features of the FormPanel, it may in general make more sense to use a ContentPanel (or LayoutContainer, if you don't want the border/header) with a FormLayout.