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Posted to users@tomcat.apache.org by Roxana <mi...@gmail.com> on 2010/07/06 19:20:39 UTC
Strange difference in behavior ELSupport in Tomcat 6.0.20 and Tomcat
6.0.26
Hi,
I have a problem that i don't understand and i hope you can help me with.
I migrate from Tomcat 6.0.20 to Tomcat 6.0.26 and suddenly i get an
exception like this:
05-Jul-2010 16:22:50 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet jsp threw exception
javax.el.ELException: Cannot convert CREATION_TIME of type class
com.docbox.tag.DocboxListColumn to class
com.owt.tag.ListContent.GenericListColumn
at org.apache.el.lang.ELSupport.coerceToEnum(ELSupport.java:155)
at org.apache.el.lang.ELSupport.equals(ELSupport.java:110)
at org.apache.el.parser.AstNotEqual.getValue(AstNotEqual.java:39)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
at
org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:935)
at
org.apache.jsp.owt.list_005fcontent_jsp._jspx_meth_c_005fwhen_005f1(list_005fcontent_jsp.java:876)
at
org.apache.jsp.owt.list_005fcontent_jsp._jspx_meth_c_005fchoose_005f1(list_005fcontent_jsp.java:846)
at
org.apache.jsp.owt.list_005fcontent_jsp._jspService(list_005fcontent_jsp.java:282)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
etc etc...................................
What i don't understand is why, with the same code , Tomcat 6.0.20 didn't
complain. Is the type check in ELSupport stronger now?
In my case i try to compare two different enums: DocboxListColumn and
GenericListColumn, but they both implement interface ListColumn.
I hope you can help me with an answer
Thanks in advanced
Roxana Frunza
Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by Mark Thomas <ma...@apache.org>.
On 06/07/2010 22:20, Pid wrote:
> On 06/07/2010 18:20, Roxana wrote:
>> What i don't understand is why, with the same code , Tomcat 6.0.20 didn't
>> complain. Is the type check in ELSupport stronger now?
Have you read to EL specification to see what the correct behaviour
should be?
Have you looked at the changelog to see if there are any changes between
6.0.20 and 6.0.26 that might apply (Hint: EL related changes will be in
the Jasper sections)?
This is *open* source. Have you looked at the svn commit messages to see
if there are any relevant changes?
(Hint: tomcat.markmail.org ha a nice UI that makes this fairly easy. The
EL implementation is in the org.apache.el package)
>> In my case i try to compare two different enums: DocboxListColumn and
>> GenericListColumn, but they both implement interface ListColumn.
>>
>> I hope you can help me with an answer
See above and you should be able to find the answer yourself.
> Bit of a mystery without seeing the JSP content.
I'm fairly sure this is an application bug but without a concrete
example, it is hard to be certain.
Mark
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Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by Pid <pi...@pidster.com>.
On 06/07/2010 18:20, Roxana wrote:
> Hi,
>
> I have a problem that i don't understand and i hope you can help me with.
>
> I migrate from Tomcat 6.0.20 to Tomcat 6.0.26 and suddenly i get an
> exception like this:
>
> 05-Jul-2010 16:22:50 org.apache.catalina.core.StandardWrapperValve invoke
> SEVERE: Servlet.service() for servlet jsp threw exception
> javax.el.ELException: Cannot convert CREATION_TIME of type class
> com.docbox.tag.DocboxListColumn to class
> com.owt.tag.ListContent.GenericListColumn
> at org.apache.el.lang.ELSupport.coerceToEnum(ELSupport.java:155)
> at org.apache.el.lang.ELSupport.equals(ELSupport.java:110)
> at org.apache.el.parser.AstNotEqual.getValue(AstNotEqual.java:39)
> at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:186)
> at
> org.apache.jasper.runtime.PageContextImpl.proprietaryEvaluate(PageContextImpl.java:935)
> at
> org.apache.jsp.owt.list_005fcontent_jsp._jspx_meth_c_005fwhen_005f1(list_005fcontent_jsp.java:876)
> at
> org.apache.jsp.owt.list_005fcontent_jsp._jspx_meth_c_005fchoose_005f1(list_005fcontent_jsp.java:846)
> at
> org.apache.jsp.owt.list_005fcontent_jsp._jspService(list_005fcontent_jsp.java:282)
> at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
> at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
> etc etc...................................
>
>
>
> What i don't understand is why, with the same code , Tomcat 6.0.20 didn't
> complain. Is the type check in ELSupport stronger now?
> In my case i try to compare two different enums: DocboxListColumn and
> GenericListColumn, but they both implement interface ListColumn.
>
> I hope you can help me with an answer
Bit of a mystery without seeing the JSP content.
p
Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by Mark Thomas <ma...@apache.org>.
On 27/09/2010 03:39, sbrejeon wrote:
> The spec says that "If A or B is an enum, coerce both A and B to enum, apply
> operator".
> Does't it simply mean that both A and B must be coercible to enums. instead
> of if A is an enum then B must be an enum of type A, or vice versa.
No. Both must be of the same type. There are several reasons for this:
- There is no provision in the EL spec for enum to enum type conversion
via a string value
- If both A & B are enums, should both values be coerced to enum A or
enum B? One may work whilst the other fails. If the spec permitted this
then the behaviour in this case would need to be defined. It isn't.
- Section 1.17 is clear the String values must be used to trigger enum
type conversion
> Like the original creator of this post, I have a series of enums of
> different types that implement a common interface. I need to be able to
> compare them and I don't want to have to translate them to Strings.
The EL spec doesn't support what you are trying to do.
Mark
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Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by sbrejeon <sb...@daesim.com>.
markt-2 wrote:
>
> On 27/09/2010 02:23, sbrejeon wrote:
>> A.test==B.test throws the exception. couldn't it just return false?
>
> Such a change would put Tomcat's EL implementation in breach of the EL
> spec so this behaviour will not be changed.
>
> Mark
>
Thank you for your quick reply.
The spec says that "If A or B is an enum, coerce both A and B to enum, apply
operator".
Does't it simply mean that both A and B must be coercible to enums. instead
of if A is an enum then B must be an enum of type A, or vice versa.
in the coerceToEnum method I would return the object if it is an enum
(whatever its type is):
public final static Enum<?> coerceToEnum(final Object obj, Class type) {
if (obj == null || "".equals(obj)) {
return null;
}
if(obj.getClass().isEnum()){
return (Enum<?>)obj;
}
...
}
Like the original creator of this post, I have a series of enums of
different types that implement a common interface. I need to be able to
compare them and I don't want to have to translate them to Strings.
Regards
Sbrejeon
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Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by Mark Thomas <ma...@apache.org>.
On 27/09/2010 02:23, sbrejeon wrote:
> A.test==B.test throws the exception. couldn't it just return false?
Such a change would put Tomcat's EL implementation in breach of the EL
spec so this behaviour will not be changed.
Mark
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Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by sbrejeon <sb...@daesim.com>.
Konstantin Kolinko wrote:
>
> 2010/7/6 Roxana <mi...@gmail.com>:
> BTW, if you really need to compare apples with oranges, you can
> convert one of them or both to strings.
> Best regards,
> Konstantin Kolinko
>
http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/el/lang/ELSupport.java?revision=981816&view=markup
equals:
144 } else if (obj0.getClass().isEnum()) {
145 return obj0.equals(coerceToEnum(obj1, obj0.getClass()));
coerceToEnum(obj, type):
180 if (type.isAssignableFrom(obj.getClass())) {
181 return (Enum<?>) obj;
182 }
183
184 if (!(obj instanceof String)) {
185 throw new ELException(MessageFactory.get("error.convert",
186 obj, obj.getClass(), type));
187 }
enum A{
test
}
enum B{
test
}
A.test==B.test throws the exception. couldn't it just return false?
Regards
Sbrejeon
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Re: Strange difference in behavior ELSupport in Tomcat 6.0.20 and
Tomcat 6.0.26
Posted by Konstantin Kolinko <kn...@gmail.com>.
2010/7/6 Roxana <mi...@gmail.com>:
>
> What i don't understand is why, with the same code , Tomcat 6.0.20 didn't
> complain. Is the type check in ELSupport stronger now?
Yes, it is stronger.
> In my case i try to compare two different enums: DocboxListColumn and
> GenericListColumn, but they both implement interface ListColumn.
>
The chapter 1.8.2 of the EL spec (jsp-2_1-fr-spec-el.pdf) says that
equals operator is applied as follows:
If A or B is an enum, coerce both A and B to enum, apply operatorr
BTW, if you really need to compare apples with oranges, you can
convert one of them or both to strings. There is no string "concat"
operator in EL, but there is support for "Composite expressions",
such as “${firstName} ${lastName}”
Best regards,
Konstantin Kolinko
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