Return correct subclass from relationship

I have a model with this design: Gene is located on either Chromosome or Contig. At the moment I’m solving this in the model by creating a class Feature from which both Chromosome and Contig inherit. The RelationshipTo is restricted to specifying a single class, so node I have code similar to:

class Feature(StructuredNode):
    name = StringProperty()
    location = RelationshipTo('Feature', 'LOCATED_ON', cardinality=One)

class Gene(Feature):
    description = StringProperty()

class Chromosome(Feature):
    pass

class Contig(Feature):
    pass

In the real model, Contig and Chromosome have different attributes. The problems that arise with this model are that:

1. A spurious label (Feature) is introduced into the database.
2. When querying for location (gene.location.all()) a Feature is returned, not the actual Chromosome or Contig that the gene is located on.

Inside the code the correct label is identified during querying but the actual object returned is of the superclass.

[robinedwards]

Hey apologies my brain wasn’t in gear yesterday.

We need to be a little bit careful as I think there is some existing functionality built around assuming abstract nodes dont have labels… However your case above (relation to abstract node) should definitely raise a friendly error message in the current release of neomodel.

What you are trying to achieve is quite similar to #126

Now I am not opposed to changing the behaviour of inheritance in a major release of neomodel, the current situation is confusing at best. In fact the whole handling of ‘abstract nodes’ is hacky and unpythonic. One issue with the subclass behaviour is when someone wants to build a model which actually points to the super class (none abstract) it becomes tricky.

[aanastasiou]

@pvanheus Can I please ask if you have tried version 3.3.1? The changes there would cover this use-case I wonder if this would be enough to close this issue (?).