Hi,
I want to share a table display issue we spent a few days on fixing when
moving our tomcat webapp from tomcat 6.0.16 to 6.0.32.
It took us a while to understand that an 'offers' page does not work correctly
(does not display a table) not because of a data problem (We have moved to a
new api with the offers (coreg) host, and to OJF7.14) but because of a ui issue.
That was after we concluding that the page stops working with the other change
but with tomcat Tomcat 6.0.32.
Drilling down we find that the Tomcat versions from which the problem starts we
have found that the problem arises specifically on Tomcat 6.0.29.
In parallel investigating this we saw the problem relates to the way table are
built on the page.
This is a dynamic build of tables (table ids, for each loop using the ids,
javascript manipulation using the ids). And furthermore, the parameter there
were used to build the dynamic ids was an *Enum*.
The enum that was used was built like this:
{code}
public enum OfferType {
LEISURE,
BUSINESS;
public static OfferType fromString(String str) {
if (StringUtils.isNotEmpty(str)) {
if
(str.equals(LEISURE.toString())) {
return LEISURE;
}
else if
(str.equals(BUSINESS.toString())) {
return BUSINESS;
}
}
return null;
}
public String toString() {
switch (this) {
case LEISURE:
return
"Leisure";
case BUSINESS:
return
"Business";
default:
return "";
}
}
}
{code}
As we use the enum for string in the page the toString() method were called.
The method output was different from the OfferType.name output. This mismatch
caused an inconsistency between the dynamically created tables and reading the
table ids. A mismatch between to CamelCase output of toString() and the
upperCase output of OfferType.name.
h3. So why this happened when moving to Tomcat 6.0.32?
This is [why|https://issues.apache.org/bugzilla/show_bug.cgi?id=50105].
You can see was fixed in [Tomcat
v.6.0.29|http://tomcat.apache.org/tomcat-6.0-doc/changelog.html]
h3. In short
Tomcat fix to match the EL specification (to use Enum.name instead of
toString()) switched on the mismatch problem. Until the fix only the toString
method was used. After the change the Enum.name was used for the EL expression
and toString for other usage of the Enum.
h3. Simple fix.
In our case it was enough to take out the toString method and get rid of the
CamelCase string.
{code}
public enum OfferType {
LEISURE,
BUSINESS;
// we override just for get rid of the potential exceptions of
valueOf.
// Nothing to do with the problem described.
public static OfferType fromString(String str) {
try {
return valueOf(str);
}
catch(final Exception exception) {
return null;
}
}
}
{code}
