---
Known Pitfalls
---
Kai Moritz
---
Annotated classes in dependencies are not found.
hibernate4-maven-plugin does not scan transitive dependencies for
annotated classes. If some of your annotated classes are hidden in a
transitive dependency, you can simply add that dependency explicitly.
hibernate4-maven-plugin always needs a database-connection
The default-configuration uses the EXPORT-target of the SchemaExport-Tool.
If you do not need to create a database with the evaluated schema, you can
use the NONE- or the SCRIPT-target.
This can be achieved with the command-line parameter
<<<-Dhibernate.export.target=SCRIPT>>> or with the following configuration:
------------
SCRIPT
------------
But even when no database is to be created, hibernate always needs to know
the dialect. Hence, the plugin will fail if this parameter is missing!
Dependency for driver-class XYZ is missing
One regular problem is the scope of the jdbc-driver-dependency.
It is very unlikely, that this dependency is needed at compile-time.
So a tidy maven-developer would usually scope it for <<>>.
But this will break the execution of the <<>>.
Since it will not be able to see the needed dependency, it will fail with
an error-message like:
---------------
[INFO] Gathered hibernate-configuration (turn on debugging for details):
[INFO] hibernate.connection.username = sa
[INFO] hibernate.connection.password =
[INFO] hibernate.dialect = org.hibernate.dialect.HSQLDialect
[INFO] hibernate.connection.url = jdbc:hsqldb:/home/kai/mmf/target/mmf;shutdown=true
[INFO] hibernate.connection.driver_class = org.hsqldb.jdbcDriver
[ERROR] Dependency for driver-class org.hsqldb.jdbcDriver is missing!
[INFO] ------------------------------------------------------------------------
[ERROR] BUILD ERROR
[INFO] ------------------------------------------------------------------------
[INFO] org.hsqldb.jdbcDriver
[INFO] ------------------------------------------------------------------------
[INFO] For more information, run Maven with the -e switch
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 2 seconds
[INFO] Finished at: Thu Nov 29 11:31:14 CET 2012
[INFO] Final Memory: 32M/342M
[INFO] ------------------------------------------------------------------------
---------------
A quick workaround for this error would be, to delete the runtime-constraint
for the jdbc-driver-dependency.
A much cleaner way is, to (additionally) ad the dependency, to the
plugin-definition:
---------------
de.juplo
hibernate4-maven-plugin
${project.version}
export
org.hsqldb
hsqldb
2.2.8
---------------
This is also the best way, if you use a different jdbc-driver for
testing, than in production.
Because otherwise, this dependency will unnecessarily bloat the
runtime-dependencies of your project.
DBUnit {fails} after execution of hibernate4 was skipped because nothing has changed
If hibernate4-maven-plugin skips its excecution, this may lead to errors in
other plugins.
For example, when importing sample-data in the automatically created database
with the help of the {{{http://mojo.codehaus.org/dbunit-maven-plugin/}dbunit-plugin}},
the <<>>-operation may fail because of foreign-key-constraints,
if the database was not recreated, because the hibernate4-maven-plugin has
skipped its excecution.
A quick fix to this problem is, to {{{./force.html}force}}
hibernate4-maven-plugin to export the schema every time it is running.
But to recreate the database on every testrun may noticeable slow down your
development cycle, if you have to wait for slow IO.
To circumvent this problem, hibernate4-maven-plugin signals a skipped
excecution by setting the maven property <<<${hibernate.export.skipped}>>> to
<<>>.
You can configure other plugins to react on this signal.
For example, the dbunit-plugin can be configured to skip its excecution, if
hibernate4-maven-plugin was skipped like this:
------------
org.codehaus.mojo
dbunit-maven-plugin
${hibernate.export.skipped}
------------
The database will not be recreated after a manual drop/clean
If one manually drops the database or removes the hsqldb-files, it will not
be recreated by the hibernate4-maven-plugin, because it cannot detect, that
the database needs to be recreated.
This happens, because the plugin will not recreate the database if neither
the configuration nor the annotated classes have changed, because an
unnecessary drop-create-cycle might take a long time. The plugin will
report that like this:
-------------
[INFO] No modified annotated classes found and dialect unchanged.
[INFO] Skipping schema generation!
-------------
If one always uses <<>> for cleanup, this will not happen.
Otherwise the recreation must be {{{./force.html}forced}}:
-------------
mvn hibernate4:export -Dhibernate.export.force=true
-------------
The hibernate4:export goal is not executed, when tests are skipped
The hibernate4-maven-plugin automatically skips its execution, when
<<>> is set to <<>>. If you need it to be always
executed, you can configure that explicitly like this:
------------
de.juplo
hibernate4-maven-plugin
...
false
------------
Background-information for this design-decission can be found on the extra
page {{{./skip.html}To skip or not to skip: that is the question}}...