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Posted to dev@myfaces.apache.org by "Hanspeter Dünnenberger (JIRA)" <de...@myfaces.apache.org> on 2010/09/10 17:39:33 UTC
[jira] Created: (MYFACES-2915) UIComponent attribute defaults are
not used when bound to managed bean property by EL, even if the managed
bean property is null
UIComponent attribute defaults are not used when bound to managed bean property by EL, even if the managed bean property is null
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Key: MYFACES-2915
URL: https://issues.apache.org/jira/browse/MYFACES-2915
Project: MyFaces Core
Issue Type: Improvement
Components: JSR-314
Affects Versions: 2.0.1
Reporter: Hanspeter Dünnenberger
As asked by Leonardo I open this issue in relation to issue https://javaserverfaces.dev.java.net/issues/show_bug.cgi?id=1805 on mojarra to check if MyFaces can do the same. For full description see issue above, short description below:
Assigning a UIComponent attribute with EL expression disables the default value handling that some attribute feature (e.g. rendered==null is the same as rendered==true). Since EL expression never evaluates to null an expression like rendered="#{bean.rendered} with bean.rendered=null will evaluate to False, since for the rendered attribute the expected type for the ValueExpression is Boolean.
The proposed change would be to use Object as expected type to allow null evaluation from EL and convert to the really expected type later in TagValueExpression. For details see original issue 1805 on mojarra.
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[jira] Commented: (MYFACES-2915) UIComponent attribute defaults are
not used when bound to managed bean property by EL, even if the managed
bean property is null
Posted by "Jakob Korherr (JIRA)" <de...@myfaces.apache.org>.
[ https://issues.apache.org/jira/browse/MYFACES-2915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12909191#action_12909191 ]
Jakob Korherr commented on MYFACES-2915:
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I agree with Leonardo. This should be solved in the EL implementation.
Furthermore the EL coercion will maybe be configurable in the next version. We'll see.
> UIComponent attribute defaults are not used when bound to managed bean property by EL, even if the managed bean property is null
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: MYFACES-2915
> URL: https://issues.apache.org/jira/browse/MYFACES-2915
> Project: MyFaces Core
> Issue Type: Improvement
> Components: JSR-314
> Affects Versions: 2.0.1
> Reporter: Hanspeter Dünnenberger
> Attachments: ComponentAttributeValueExpression.patch
>
>
> As asked by Leonardo I open this issue in relation to issue https://javaserverfaces.dev.java.net/issues/show_bug.cgi?id=1805 on mojarra to check if MyFaces can do the same. For full description see issue above, short description below:
> Assigning a UIComponent attribute with EL expression disables the default value handling that some attribute feature (e.g. rendered==null is the same as rendered==true). Since EL expression never evaluates to null an expression like rendered="#{bean.rendered} with bean.rendered=null will evaluate to False, since for the rendered attribute the expected type for the ValueExpression is Boolean.
> The proposed change would be to use Object as expected type to allow null evaluation from EL and convert to the really expected type later in TagValueExpression. For details see original issue 1805 on mojarra.
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[jira] Commented: (MYFACES-2915) UIComponent attribute defaults are
not used when bound to managed bean property by EL, even if the managed
bean property is null
Posted by "Leonardo Uribe (JIRA)" <de...@myfaces.apache.org>.
[ https://issues.apache.org/jira/browse/MYFACES-2915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12908598#action_12908598 ]
Leonardo Uribe commented on MYFACES-2915:
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I have checked and done some examples, and the patch proposed is related to another problem in EL api.
The problem resides in the coercion rules used by EL. The patch just override them but only partially. If the EL is more complex than a single expression, it is coerced using the standard rules (because the expression is parsed into sub expressions internally by the EL implementation). Note the patch also has the effect that all EL expressions created by facelets are affected, so if the user creates an expression directly using the expression factory it is expected the original rules applies.
The solution is override the EL coercion rules. It is known libraries like "juel" provides a way outside EL spec to override these rules(see http://juel.sourceforge.net/guide/advanced/index.html Advanced Topics - Customizing Type Conversion). In this case, I don't think add a param to myfaces or mojarra could result in the expected behavior for all cases, so apply this patch could unfortunately lead to inconsistencies.
> UIComponent attribute defaults are not used when bound to managed bean property by EL, even if the managed bean property is null
> --------------------------------------------------------------------------------------------------------------------------------
>
> Key: MYFACES-2915
> URL: https://issues.apache.org/jira/browse/MYFACES-2915
> Project: MyFaces Core
> Issue Type: Improvement
> Components: JSR-314
> Affects Versions: 2.0.1
> Reporter: Hanspeter Dünnenberger
> Attachments: ComponentAttributeValueExpression.patch
>
>
> As asked by Leonardo I open this issue in relation to issue https://javaserverfaces.dev.java.net/issues/show_bug.cgi?id=1805 on mojarra to check if MyFaces can do the same. For full description see issue above, short description below:
> Assigning a UIComponent attribute with EL expression disables the default value handling that some attribute feature (e.g. rendered==null is the same as rendered==true). Since EL expression never evaluates to null an expression like rendered="#{bean.rendered} with bean.rendered=null will evaluate to False, since for the rendered attribute the expected type for the ValueExpression is Boolean.
> The proposed change would be to use Object as expected type to allow null evaluation from EL and convert to the really expected type later in TagValueExpression. For details see original issue 1805 on mojarra.
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