Question

I really didn’t know how to write the title for this problem 😛

So in google app engine I want to create a class that can have ‘sons’ of the same type:

class Chapter(db.Model):
    title = db.StringProperty(required=True)
    note = db.TextProperty()
    father = db.ReferenceProperty(Chapter, collection_name='sons')
    order = db.IntegerProperty(default=0)

and I get the error

NameError: name 'Chapter' is not defined

Is it possible to create this? Or is this a really stupid idea?

Answer 1

You need to use SelfReferenceProperty

class Chapter(db.Model):
    title = db.StringProperty(required=True)
    note = db.TextProperty()
    father = db.SelfReferenceProperty(collection_name='sons')
    order = db.IntegerProperty(default=0)