[richfaces-issues] [JBoss JIRA] (RF-12353) Incorrect documentation/taglib on <a4j:param>

[Brian Leathem (JIRA)]

     [ https://issues.jboss.org/browse/RF-12353?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Brian Leathem updated RF-12353:
-------------------------------

    Story Points: 0.25

    
> Incorrect documentation/taglib on <a4j:param>
> ---------------------------------------------
>
>                 Key: RF-12353
>                 URL: https://issues.jboss.org/browse/RF-12353
>             Project: RichFaces
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: component-a4j-core, doc
>    Affects Versions: 4.2.0.Final, 4.2.2.Final
>         Environment: no matter
>            Reporter: Alexander Kiselyov
>            Priority: Trivial
>              Labels: String, a4j:param, assignTo, converter
>             Fix For: 4.3.0.Milestone2
>
>
> Technical background (RichFaces developers can easy skip it):
> ----
> <a4j:param> performs setting of its value into an expression specified in "assignTo" attribute. As this component is set as Action listener for ActionSource parent - org.richfaces.component.AbstractParameter.processAction(ActionEvent) is called. This method directly retrieves request parameter with this parameter's name/clientId:
> String requestValue = context.getExternalContext().getRequestParameterMap().get(getName());
> and then, if converter's not found, sets it as a value of an expression, specified in "assignTo":
> {code}
> if (requestValue != null) {
>   Class<?> type = updateBinding.getType(elContext);
>   Converter converter = createConverter(context, type);
>   ...
> }
> if (null != convertedValue) {
>  updateBinding.setValue(elContext, convertedValue);
> }
> {code}
> When our expression value has reifiable type, for which JSF (or app developer) has registered a converter (for instance - Boolean) - all's peachy keen. But when developer uses, e.g., Map - expression's type (got in updateBinding.getType(ELContext)) is Object, and we're starting to receive strings in Map, which is probably parameterized with anything. Also this situation applies to "non-standard" reference types (user-declared JavaBean, for instance).
> {code}
> org.richfaces.view.facelets.html.ParameterHandler:
> org.richfaces.view.facelets.html.ParameterHandler.ActionParamMetaRule.applyRule(String, TagAttribute, MetadataTarget):
> ...
> else if ("converter".equals(name)) {
>                     if (attribute.isLiteral()) {
>                         return new LiteralConverterMetadata(attribute.getValue());
>                     } else {
>                         return new DynamicConverterMetadata(attribute);
>                     }
>                 }
> ...
> {code}
> I.e. <a4j:param> tag handler designed to accept "converter" attribute, which can appropriately convert value, passed from client.
> ----
> [a4j:param VDL Doc|http://docs.jboss.org/richfaces/4.2.X/4.2.2.Final/vdldoc/a4j/param.html] has no mention of it, and value/assignTo attributes type specified as "java.lang.Object". a4j.taglib.xml has no mention of it, so developers have no chance to discover it, e.g., through the content assist, [Rich Component Reference|http://docs.jboss.org/richfaces/4.2.X/4.2.2.Final/Component_Reference/en-US/html_single/#sect-Component_Reference-Actions-a4jparam] has only two sentences about it, which are *very easy to miss*.
> Also, [RichFaces Showcase|http://showcase.richfaces.org/richfaces/component-sample.jsf?demo=param&sample=clientParam&skin=blueSky] contains no example, which uses "converter" attribute.

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