Sylvain Wallez wrote:
Sylvain Wallez wrote:
Now I think that every widget should be able to have validators. Some use cases:
- on a form, to perform some inter-field validations, and even application-level validation if the means to access application data is given to the validator.
- on a repeater, to check e.g. uniqueness of some values among rows
- on a group (i.e. "class", "struct", etc) where some validation between the various widgets of the group may be wanted (actually, a form is a group)
+1. I presume that it will be possible to define form-/repeater- level validators in form definition file, as well as set them from Java. Am I right?
By "set them from Java", do you mean setting validators for a particular instance of a form? What are the use cases behind this? Is it to allow communication between the form and the application context? If yes, what do you think of special "value-holder" widgets that would expose the communication contract between the form and the application?
The current ValidationRule interface is not suited for this, as it is really tied to widgets that have a value, which neither form nor repeater have.
So my idea is to introduce a generalized "WidgetValidator" with a single "validate(Widget w, FormContext ctx)" method. The current ValidationRule implementations we have today can then simply become subclasses of a "FieldValidator" abstract class.
No objections. What about suggestion to allow nested validators?
Thinking a bit more about this, I think we must clearly define the semantic of nesting: obviously, if the parent validation succeeds, child validators are checked. But what if the parent validator fails? Does the form fail or do we simply ignore the child validators?
I think we're actually seeing the birth of a "if" validator that would allow conditional validation...
Anyway, the generalized validator will make this possible. So let's do it one step at a time.
Sylvain
-- Sylvain Wallez Anyware Technologies http://www.apache.org/~sylvain http://www.anyware-tech.com { XML, Java, Cocoon, OpenSource }*{ Training, Consulting, Projects } Orixo, the opensource XML business alliance - http://www.orixo.com
