Using an expression to set checkbox value

Question

Hi,
I am working on an application that has a whole suite of javabeans where boolean fields are expressed as Y/N flags. Regardless of whether or not this is a good idea, that is how it is and I cannot change them (it came about because the beans map straight to database tables that do not accept Boolean datatypes).
I am wanting to render these fields as checkboxes, ideally so that they can be properly bound to a backing bean, but it would suffice if I could just display the checkbox and have it only readonly (doesn't have to map back to the backing bean).
I have tried to write a converter to handle these fields, but MyFaces doesn't like having a non-boolean binding for the field, even with the converter supplied.
To just try and render the non-editable checkbox I would to be able to do the following:
<h:selectBooleanCheckbox value="#{group.external == 'Y'}" />This works fine when the page is displayed, but it still tries to update the model when the form is submitted and throws the following exception:
javax.faces.el.EvaluationException: Cannot set value for expression '#{group.external == 'Y'}' to a new value of type java.lang.Boolean
Any ideas would be appreciated...

Answer 1

I suggest it: on your JSF managed bean wrap your String value.
String strExternal;
public boolean isExternal () {
   boolean f =  "Y".equalsIgnoreCase(strExternal);
   return f;
public void setExternal(boolean f) {
this.strExternal =  (f ? "Y" : "N");
}Internally you work with Stirng values, however MyFaces with booleans.