XPages: Binding customizable scoped variables to fields in custom controls

Edit 13.09.2012: As commenter, Bas van Gestel pointed out. This method of doing things is outdated. I can't remember the reason why I had issues, but this is a better way of doing it (where fieldName is a custom property):

#{viewScope[compositeData.fieldName]}

I stumbled onto a weakness(?) in the XPages editor today. I have a complex field that I use twice in an XPage. The only difference between the two instances of the field is the rendered-property, and the data binding. To avoid copy/pasting(/screwing up in the long run), I decided to make a custom control of the field.

The rendered-property is set on the custom control, instead of the field. The data binding is a scoped variable. I couldn't find a way to compute the name of the scoped variable in the data binding section. To work around this (flaw?), I set the data binding afterPageLoad.

Here's the code:

// Set value-binding when page loads
var application = facesContext.getApplication();
var scopedField = compositeData.scopedField;
var valueBinding = application.createValueBinding( '#{viewScope.' + scopedField + '}')
getComponent( 'text-filter' ).setValueBinding( 'value', valueBinding );

text-filter is the id of the field.
scopedField is the custom property that defines the name of the scoped variable

If you have a custom control that's used many times inside a page, you may need private scoped variables.

Share and enjoy!