[jira] Issue Comment Edited: (TILES-338) AddAttributeTag only uses the first "value" ever set

["Zach Bailey (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/struts/browse/TILES-338?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=45173#action_45173 ] 

znbailey edited comment on TILES-338 at 12/8/08 11:38 AM:
-------------------------------------------------------------

Please note that while this Tag overrides the release() method which DOES null the value instance member, this method is not guaranteed to be called between every single invocation of the tag (e.g. when the tag is used multiple times on one page). For more information please see the tag lifecycle as documented here:

http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/tagext/Tag.html

especially:

Methods

There are two main actions: doStartTag and doEndTag. Once all appropriate properties have been initialized, the doStartTag and doEndTag methods can be invoked on the tag handler. Between these invocations, the tag handler is assumed to hold a state that must be preserved. After the doEndTag invocation, the tag handler is available for further invocations (and it is expected to have retained its properties).

Lifecycle

Lifecycle details are described by the transition diagram below, with the following comments:

image: http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/tagext/doc-files/TagProtocol.gif

[1] This transition is intended to be for releasing long-term data. no guarantees are assumed on whether any properties have been retained or not.
[2] This transition happens if and only if the tag ends normally without raising an exception
[3] Some setters may be called again before a tag handler is reused. For instance, setParent() is called if it's reused within the same page but at a different level, setPageContext() is called if it's used in another page, and attribute setters are called if the values differ or are expressed as request-time attribute values.
Check the TryCatchFinally interface for additional details related to exception handling and resource management.

Once all invocations on the tag handler are completed, the release method is invoked on it. Once a release method is invoked all properties, including parent and pageContext, are assumed to have been reset to an unspecified value. The page compiler guarantees that release() will be invoked on the Tag handler before the handler is released to the GC.




      was (Author: znbailey):
    Please note that while this Tag overrides the release() method which DOES null the value instance member, this method is not guaranteed to be called between every single invocation of the tag (e.g. when the tag is used multiple times on one page). For more information please see the tag lifecycle as documented here:

http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/tagext/Tag.html

especially:

Methods

There are two main actions: doStartTag and doEndTag. Once all appropriate properties have been initialized, the doStartTag and doEndTag methods can be invoked on the tag handler. Between these invocations, the tag handler is assumed to hold a state that must be preserved. After the doEndTag invocation, the tag handler is available for further invocations (and it is expected to have retained its properties).

Lifecycle

Lifecycle details are described by the transition diagram below, with the following comments:

[1] This transition is intended to be for releasing long-term data. no guarantees are assumed on whether any properties have been retained or not.
[2] This transition happens if and only if the tag ends normally without raising an exception
[3] Some setters may be called again before a tag handler is reused. For instance, setParent() is called if it's reused within the same page but at a different level, setPageContext() is called if it's used in another page, and attribute setters are called if the values differ or are expressed as request-time attribute values.
Check the TryCatchFinally interface for additional details related to exception handling and resource management.

Once all invocations on the tag handler are completed, the release method is invoked on it. Once a release method is invoked all properties, including parent and pageContext, are assumed to have been reset to an unspecified value. The page compiler guarantees that release() will be invoked on the Tag handler before the handler is released to the GC.



  
> AddAttributeTag only uses the first "value" ever set
> ----------------------------------------------------
>
>                 Key: TILES-338
>                 URL: https://issues.apache.org/struts/browse/TILES-338
>             Project: Tiles
>          Issue Type: Bug
>          Components: tiles-jsp (jsp support)
>    Affects Versions: 2.1.0
>            Reporter: Zach Bailey
>
> In AddAttributeTag#doAfterBody:
> /**
>      * Save the body content of this tag (if any).
>      *
>      * @return It returns <code>SKIP_BODY</code>.
>      */
>     public int doAfterBody() {
>         if (value == null && bodyContent != null) {  //bug here
>             value = bodyContent.getString();
>             type = "string";
>         }
>         return (SKIP_BODY);
>     }
> The value of this tag is only being updated if there is not already a value set. So, when this tag is used twice in succession on a page, it will always only use the first "value" ever set!!!
> I looked back at the older Tiles 2.0.6 version we were using and the code is correct in that version - there is no "value == null" check. So, it looks as though someone added this little check at some point in the 2.1 release, but it seems to severely break things (at least for me!)
> I see two ways of fixing this - 
> 1.) Simply remove the value == null check, or if this check is in place for a reason,
> 2.) Reset value to null after each execution of the tag in doEndTag, or doFinally() from the TryCatchFinally interface:
> http://java.sun.com/j2ee/1.4/docs/api/javax/servlet/jsp/tagext/TryCatchFinally.html

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