字符串解耦和字段名称

Question

I have a number of domain/business objects, which when used in a hibernate criteria are referenced by the field name as a string, for example :

Criteria crit = session.createCriteria(User.class);
Order myOrdering = Order.desc("firstname");
crit.addOrder(myOrdering);

Where firstname is a field/property of User.class .

I could manually create an Enum and store all the strings in there; is there any other way that I am missing and requires less work(I'll probably forget to maintain the Enum).

Answer 1

I'm afraid there is no a good way to do that. Even if you decide to use reflections, you'll discover the problem only when the query will run.

But there is a little bit better solution how to discover the problem early: if you use the Named Queries (javax.persistence.NamedQueries) you'll get all your queries compiled as soon as your entities are processed by Hibernate, so basically it will happen during the server's start-up. So if some object was changed breaking the query, you'll know about it the next time you start the server and not when the query is actually run.

Hope it helps.

Answer 2

This is one of the things that irritates me about Hibernate.

In any case, I've solved this in the past using one of two mechanisms, either customizing the templates used to generate base classes from Hibernate config files, or interrogating my Hibernate classes for annotations/properties and generating appropriate enums, classes, constants, etc. from that. It's pretty straight-forward.

It adds a step to the build process, but IMO it was exactly what I needed when I did it. (The last few projects I haven't done it, but for large, multi-dev things I really like it.)