Doctrine 2关联继承与不同的类

Question

I'm using Doctrine 2 and single table inheritance, my topmost entity hierarchy is:

JS_File --> [one to many] --> JS_File_Version

And then my sub-class entity hierarchy is:

JS_Image (extends JS_File) --> [one to many] --> JS_Image_Version (extends JS_File_Version)

The inheritance mapping works perfectly for JS_File and JS_Image, and the association mapping works perfectly for JS_File --> JS_File_Version. But, when it comes to map the "versions" association on JS_Image I get:

'Property "versions" in "JS_Image" was already declared, but it must be declared only once'

I understand why this is, the association is being inherited from JS_File and I can't overwrite it, but how do I achieve what I'm trying to do? Basically, with inheritance, how can I tell Doctrine to use a different targetEntity for the sub-classes association.

Answer 1

Looks like what I'm trying to do isn't possible (having both JS_File and JS_Image as concrete entities). I've followed the advice of someone from the doctrine-user mailing list instead:

The way I solved this was to use an abstract base class and then define the actual mappings on the subclasses. For example, you could do something like:

JS_AbstractFile with subclasses: JS_File and JS_Image JS_AbstractVersion with subclasses: JS_FileVersion and JS_ImageVersion

AbstractFile and AbstractVersion can define the property (and getter/setters) but you shouldn't define any mapping information for the field. Then in your subclass you re-define the property along with mapping information (at least, thats how I did it since I used annotations)

http://groups.google.com/group/doctrine-user/msg/243f355191d3a512