[
Date Prev][
Date Next][
Thread Prev][
Thread Next][
Date Index][
Thread Index]
[
List Home]
|
Re: [eclipselink-users] SessionCustomizer to modify/detect database platform: impossible
|
A third workaround suggested by a colleague
- Use the eclipselink.metadata-source persistence unit property to point to a
custom class that extends org.eclipse.persistence.jpa.metadata.MetadataSourceAdapter
- In your class implement
public Map<String, Object> getPropertyOverrides(Map<String, Object>
properties, ClassLoader classLoader, SessionLog log)
and in the case where you need to specify the new platform, add the
eclispelink.target-database property to that list.
This method is called immediately before login and should provide you what
you need.
-Tom
On 21/02/2013 8:46 AM, Tom Ware wrote:
Hi Laird,
It looks like the use-case where you want auto-detection of database platform
for all but a single platform is not well covered by the current code base. I
see you've filed bug 401388 for this issue. The easiest way for us to address
your specific issue is to make the isInformixOuterJoin flag a boolean on the
InformixPlatform that could be set in your customizer, this could be done
quickly, but would not help you for your 2.3.2 deployment.
The possible workarounds I see are:
1. Pass the new platform as a property when your EntityManagerFactory is created
2. Try to override the auto-detection yourself. This would involve roughly the
following steps
- Use the eclipselink.target-database property in your persistence.xml to set
a platform... Any platform. (this setting will make EclipseLink avoid it's own
auto-detection code)
- In a prelogin event use the code from our
DatabaseSessionImpl.loginAndDetectDatasource method to use our auto-detection
code and then override the InformixPlatform if it is detected. Here is the code
as it exists. You could override the platformName if it was the InformixPlatform:
--
try {
String vendorNameAndVersion =
conn.getMetaData().getDatabaseProductName() +
conn.getMetaData().getDatabaseMajorVersion();
platformName =
DBPlatformHelper.getDBPlatform(vendorNameAndVersion, getSessionLog());
getLogin().setPlatformClassName(platformName);
} catch (EclipseLinkException classNotFound) {
if (platformName.indexOf("Oracle") != -1) {
// If we are running against Oracle, it is possible
that we are running in an environment where
// the OracleXPlatform class can not be loaded. Try
using OraclePlatform class before giving up
getLogin().setPlatformClassName(OraclePlatform.class.getName());
} else {
throw classNotFound;
}
}
--
Sorry this is so involved.
-Tom
On 21/02/2013 1:43 AM, Laird Nelson wrote:
Is it possible to write a SessionCustomizer that jumps in early enough to
install a custom platform on a session, AND that is immune to the platform's
jettisoning of any installed platform upon initial login?
One of the first things that DatabaseSessionImpl.java does is to set the
session's associated platform--conveniently installed by my session
customizer--to null. WTF.
In other words, a SessionCustomizer that I've written happily installs a new
platform...which is then immediately overwritten by the core EclipseLink
innards. I see no way to prevent this overwriting.
A SessionEventListener which activates after a postLogin() event that does the
same thing results in dozens of NullPointerExceptions from deep within
QuerySequence.java later on in the persistence unit lifecycle, so that's not an
option.
Relevant StackOverflow question:
http://stackoverflow.com/questions/14899458/what-is-the-proper-way-to-have-a-user-authored-eclipselink-databaseplatform-subc
Best,
Laird
--
http://about.me/lairdnelson
_______________________________________________
eclipselink-users mailing list
eclipselink-users@xxxxxxxxxxx
https://dev.eclipse.org/mailman/listinfo/eclipselink-users
