Wake Up Hibernate

Editor's Note: This post is not about bears and their sleeping habits. Tommy and millhousethecat, you can stop reading now. Really, stop reading.

I finally had the chance to use Hibernate on a recent project. Hibernate is a full-featured and popular API, but it has some problems. Here are my grievances.

Step away from the thesaurus

I feel like it was designed by pompous thesaurus-loving assholes. If you want to query a table and bring back just one column, what do you do? Oh, well that's simple. Add a Projection. Huh? I never would have guessed that. By coming up with crazy names for simple operations, the creators of Hibernate have taken away something very important. Developers new to Hibernate can't discover and learn it by doing (coding). The API is not in touch with reality. Let's go to the javadoc for the Projection interface:

"An object-oriented representation of a query result set projection in a Criteria query. Built-in projection types are provided by the Projections factory class. This interface might be implemented by application classes that define custom projections."

Good job Gavin King. Use the word you are defining in the definition. If I didn't have someone helping me with Hibernate, it would have taken me hours to discover this feature.

Reflection is cool...sometimes

A major selling point for Hibernate is that you don't have to change your object hierarchy in order to get persistable objects. What the hell does that mean? Usually ORM's require the user to subclass some PersistableObject in order for the object to be persistable. This is usually too restrictive for mature code-bases. With Hibernate, any POJO can be persistable. How do they that? -- Reflection my friend.

Reflection is cool until you need to do some debugging. Let's say a private instance variable is being set, and you want to know who/what is setting it. OK, put a breakpoint on the setter for the instance variable in question and see what happens. When Hibernate changes the value, you'll see nothing. Hibernate stealthily sets the value using reflection and the debugger is clueless. OK, put a watch on the instance variable. That will do the trick, right? Wrong. The same thing happens, Hibernate changes the variable and the debugger has no idea the value changed.

Lazy initialization error

This is infuriating for the first-time user. Hibernate only fetches things when it absolutely needs to. By default it's...well...lazy.

For example (pseudo code):

get session
fetch someObject from the session
close session

someObject.getAValue() --->  Boom!
Lazy Initialization Exception

There are three fixes to this problem:

1. Leave the session open while you are accessing the object values.


2. Configure Hibernate to not use lazy initialization.


3. Stop using Hibernate. :)

There are more things that bug me about Hibernate, but I'm tired of typing and I'm sure you're tired of reading. Is anyone still reading?