Hi,

Does Hibernate 3 allow arbitrary prefixes for field names?

I have an existing business model in which the POJO instance variables all start with an underscore (e.g. private String _aField) and it would be good if I could configure the mappings to handle this, such as by direct specification of the prefix string or of the accessor method-names.

I've experiemented, and searched the documentation and forums, without success, and was wondering if I missed something.

Thanks

NamingStrategy
http://www.hibernate.org/hib_docs/reference/en/html_single/#configuration-namingstrategy

NamingStrategy appears to be for database-object names only. Is that correct?

I'm looking for something that will allow me to have an instance variable begin with an underscore (_aField) while using standard getters and setters (getAField, rather than get_aField) to access it. Currently, Hibernate chokes because it's looking for get_aField, which doesn't exist.

are you using hbm2java or ?

No. I've just begun playing around with Hibernate, writing both the POJOs and mapping files by hand, and testing basic DB interaction.

Actually, I've just realised I can write a custom implementation of org.hibernate.property.PropertyAccessor and specify it in the mapping file using the 'default-access' attribute of 'hibernate-mapping'.

Problem solved.

I'm seeing the same thing. Hibernate 2.1.7c, Firebird 1.5.2

What version of Hibernate are you using? I was curious if 3.0 fixed this.

Originally, someone was working through our code to fix things that didn't adhere to our coding standards. They prepended the '_' to all the member variable names but didn't touch the .hbm.xml files, and then didn't run any of our integration tests, so a week or so later when we started getting "foreign key constraint violation" all over the place we didn't know why. So I started backing out changes until it worked and voila it was the underscores.

Today I tried adding the underscores in the .hbm.xml files and got:



So far I've tried:

- Change the getter/setter names to get_id()/set_id(). It can't be get_Id(), because apparenly the 'upcase the first letter' applies to the underscore rather than the 'i'. Ugly and the changes ripple, but it seemed to be working to a point. I didn't pursue it because of the inherent ugliness. It sounds like you have a large code base and you don't want to be going through it all.

- Specify access="field" for all of the properties in the mapping flies, so that Hibernate doesn't use the getters/setters at all. I suppose there could be cases where some synthesis or validation of the field should be happening and you would lose that. I tried it anyway and it broke on a joined-subclass - it said it couldn't find the _id in the subclass. I guess somehow when it calls the getter it picks up the base-class getter, but in the case of field access its not.

- Page 80 of _Hibernate in Action_ says you can write your own custom PropertyAccessor, but I haven't tried that one. Not sure what package it would have to go in, etc...

- I think for us the simplest thing is to change our coding standards, since we're early in our project. Before I go there I'm going to try creating a PropertyAccessor, though.

-Jeff

I'm using Hibernate 3.0

I also rejected the possible solutions you mentioned, for mostly the same reasons. Although, I like using the underscore prefix for instance variables: it makes it obvious which variables belong to the method and which to the object. It also means I can use logical names for method parameters, instead of creating new names which don't conflict, or of using 'this'.

Creating a PropertyAccessor is straightforward and works well. The easiest way is to simply copy org.hibernate.property.BasicPropertyAccessor and add a couple of lines to 'getterMethod' and 'setterMethod' to handle the prefix.

Thanks for the reply. How does Hibernate know about a custom PropertyAccessor? Would the PropertyAccessor I create have to remain in the net.sf.hibernate.... package (still on version 2 for now), or is there some way to 'register' the class with Hibernate?

-Jeff

You tell Hibernate about the accessor by specifying the accessor's class name via the mapping file/s, using the 'default-access' attribute of the 'hibernate-mapping' element. For example:


You can put the new accessor class anywhere, as long as it ends up in the classpath (from Hibernate's point of view). I put mine with the rest of my project's code, in a 'hibernate' package with all the other Hibernate-specific stuff.