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From "Marko Asplund" <>
Subject Re: Convert, skip validation and update model?
Date Fri, 20 Apr 2007 18:34:16 GMT
On 10/04/07, Marko Asplund wrote:
> ...
> My current approach is based on doing most of the work on the server
> side. When a user clicks a select item picker icon next to a text
> field the whole input form gets submitted. There's a special request
> parameter that is included in the request to signal that "required"
> validation should be skipped (similar to how the Optional Validation
> Framework works). The response view includes a Javascript onload
> ...

After losing some sleep over maintainability issues i came up with an
approach that i think is a bit closer to the "jsf mainstream".

One reason i originally wanted to try and abuse the "required"
attribute was that i have a custom HtmlOutputLabel that is attached to
input components. The label outputs a '*' character next to required
fields to indicate mandatory fields to the user. It also outputs the
label text in red when validation fails for a component. The
"required" attribute provided an easy way to attach metadata to a
component and make it available also outside the component, without
having to extend each component class, something i wanted to avoid.

I realized that in my case the standard JSF UIParameter component can
be used to carry metadata for a component. So now i add a UIParameter
to a component to indicate that it is required like this:

UIParameter param =

The custom label component is then able to check all the direct
descendents of its "for" component to see if the "for" component is

Actual validation is done in the application-level. All the input
components are programmatically bound to a map. There's another map
that contains the model value objects that back the inputs. The
application code calls the validation method which iterates through
the model objects. The model objects have the key with which the
corresponding components are looked up from the component map. If a
required component is missing a value, the corresponding component is
looked up and set as invalid. If one or more mandatory fields have
missing missing values, application level processing is terminated.


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