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I'm having trouble thinking this through, but basically I want to create an Elixir class called Assets which can have many Assets. So, it could look something like this (but this doesn't work, obviously):

class Asset(Entity):
    has_field('Name', Unicode)
    has_many('Assets', of_kind='Asset', inverse='Assets')

So, I would love to be able to have a 'flat' system of Assets, but I'm not sure its possible or even best.

Is there a way of doing this?

hjpotter92
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MFB
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2 Answers2

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I'm not savvy in Elixir but this is how you can do it using SQLAlchemy declarative. Hopefully the Elixir definition will be similar enough that this help you.

from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

class Employee(Base):
  __tablename__ = 'employee'
  id = Column(Integer, primary_key=True)
  name = Column(String(64), nullable=False)
Employee.manager_id = Column(Integer, ForeignKey(Employee.id))
Employee.manager = relationship(Employee, backref='subordinates',
    remote_side=Employee.id)

Note that the manager and manager_id fields are "monkey-patched" because you cannot make self-references within a class definition.

wberry
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  • Thank you, that led me to my solution! – MFB Jul 22 '11 at 00:17
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    Would you mind sharing your solution with others? Post as a separate answer and accept it. And upvoting the answer that led to the solution is also a good idea. – van Jul 22 '11 at 06:19
  • Yeah, went to post answer but couldn't due to time restrictions. Doing now – MFB Jul 22 '11 at 15:55
  • And now I have to wait till tomorrow to accept my own answer ;-) – MFB Jul 22 '11 at 15:57
  • @MFB: if this answer helped you, you will get reputation for yourself, as well as help wberry with his own reputation, if you select this answer instead. You should really only accept your own answer if nobody that responded helped you toward your solution. – SingleNegationElimination Jul 22 '11 at 16:41
  • @TokenMacGuy it did help, but it wasn't the answer as it did not show how to do it in Elixir. – MFB Jul 23 '11 at 02:43
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I figured it out, thanks to some insight from @wberry. In Elixir:

class Asset(Entity):
    has_field('Name', Unicode)
    Assets = ManyToMany('Asset')

Using that, I can do crazy things like this:

a1 = Asset(Name=u'Asset 1')
a2 = Asset(Name=u'Asset 2')
a3 = Asset(Name=u'Asset 3')

a1.Assets=[a1,a2,a3]

And it works. I love it!

MFB
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  • Glad to be of service. The Elixir syntax looks very clean, I'll have to look into it. – wberry Jul 22 '11 at 19:14
  • It is crazy clean, and if you come up against a limitation with it, you can pretty much just start coding sqlalchemy and you're under the hood. – MFB Jul 23 '11 at 07:27