[jira] [Assigned] (TAP5-2763) @RequestParameter improved blank handling

["Ben Weidig (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TAP5-2763?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ben Weidig reassigned TAP5-2763:
--------------------------------

    Assignee: Ben Weidig

> @RequestParameter improved blank handling
> -----------------------------------------
>
>                 Key: TAP5-2763
>                 URL: https://issues.apache.org/jira/browse/TAP5-2763
>             Project: Tapestry 5
>          Issue Type: Improvement
>          Components: tapestry-core
>    Affects Versions: 5.8.3
>            Reporter: Ben Weidig
>            Assignee: Ben Weidig
>            Priority: Minor
>
> As ValueEncoders are used to convert a parameter value to its actual type, only Boolean and Number-based types result directly in {{null}} for a blank value.
> All other types use their TypeCoercer-based ValueEncoder, which not necessarily work.
> However, I believe that if {{allowBlank = true}} is set, then a blank parameter should be able to lead to a {{null}} value.
> Three possible changes come to mind to support blank --> null:
>  * Always treat blank as {{null}} before passing it the ValueEncoder
>  * Add {{boolean treatBlankAsNull() default false;}} to {{@RequestParameter, or}}
>  * {{adding String blankValue() String default ""; to @RequestParameter that is used instead of the parameter value if blank}}
> Personally, I'd prefer the first option.
> The {{TypeCoercedValueEncoderFactory}} would handle {{{}Boolean{}}}/{{{}Number{}}} just like before, but @RequestParamter wouldn't crash anymore if no valid coercion is possible for an empty String.
> My proof-of-concept works and I might provide a feature branch soon.



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