One of the primary purposes of this blog is to record what I’ve learned by tedious trial and error and/or spending time down in source code I shouldn’t have had to look at. This particular topic has more than its share of discoveries. Spring Neo4j claims that it’s intended to imitate, where possible, existing persistence systems approaches. Unfortunately, […]
Category: Java Persistence Architecture (JPA) and related ORM
DBUnit and CSV reference data
The CSV capabilities of dbUnit are under-documented. Here’s the results of some pain, suffering and debug tracing: The CSV files are expected to be one-per-table. The tablename is part of the filename, thus: “TABLE1.csv”. Format is the usual, with the first row containing the column names and subsequent rows containing data. It is possible to customize the delimiters […]
JPA and overlapping complex keys
If at all possible, you should avoid setting up databases with complex keys (or compound keys, as they are sometimes known). It makes life a whole lot more complex, and in a world where everyone already says you’re taking too long because “All You Have To Do Is…”, complex isn’t a good thing. Sometimes, however, there’s just no […]
Myfaces Extensions Validator and RichFaces (Not yet)
The MyFaces extensions validator package looks like someday it will make life a lot more pleasant when designing JSF backing beans. Instead of cluttering up the markup with cumbersome extra XML, the MyFaces Extensions Validator allows you to annotation the backing bean properties. It even adopts the applicable annotations (such as nullable=false) on JPA model objects. Unfortunately, when […]
org.hibernate.PropertyAccessException: could not get a field value by reflection getter of com.mypackage.MyEntity.entityId
There are reports that messages of this sort were due to bugs in one or more Hibernate releases. But this is also a legitimate error. I wasted a lot of time before it hit me. The original code was: @SuppressWarnings(“unchecked”) public List<State> getStatesForCountry(String countryID) { final String SQLCOMMAND = “SELECT c ” + “FROM ” + State.class.getSimpleName() + […]
OpenJPA/Spring/Tomcat6
Oh, what a tangled web we weave… In theory, using JPA and Spring is supposed to make magical things happen that will make me more productive and allow me to accomplish wonderful things. Someday. At the moment, I gain tons of productivity only to waste it when deployment time comes and I have to fight the variations in […]
JBoss and OpenJPA
I developed my Technology Sandbox app using OpenJPA under Tomcat6. Since JBoss 4.2 has its own persistency mechanisms (EJB3 and Hibernate), it looked like some changes might be required to port it. It turns out that very little needed to be done. The most important thing is to get a copy of the Spring agent (in my case […]
ORM and Imprecise Data Types
JPA is great in a lot of ways. But there’s one problem a lot of people have with JPA and ORM in general – imprecise keys. Technically, this is as much a JDBC problem as an ORM problem. It just seems to cause more problems in ORM. Perhaps because ORM lets you concentrate less on the raw data […]
Detached objects and JSF
JSF and JPA have proven to be more problematic than expected. The upside of the JSF framework is that the datamodel objects can be presented more or less right up to the page view layer without recourse to Data Transer Objects (DTOs). The downside, is that what’s presented isn’t always clear, leading to the dreaded OptimisticLockingException. Officially, you […]