CODEWITHSUNDEEP
pythonsqlalchemy
Sardathrion - against SE abuse
Sardathrion - against SE abuse

Reputation: 18246

Mapping a class that contains references to another class

I have something like this:

class A ():
   [...]

class B ():
   def __init__(self):
   self.fubar = A()

And I would like to store B into a database via SQLAlchemy. I think that I need to define both A and B as two different tables -- mapping all the other properties of A and B appropriately. Then, I need to map A to B as a property but I am not sure how to do that.

Is my thinking good or did I miss something? Any idea what functions call I am missing -- or what page of the documentation covers it?

Thanks

Upvotes: 0

Views: 72

Answers (1)

Ferdinand Beyer
Ferdinand Beyer

Reputation: 67147

You should indeed define two database entities, A and B, and a 1:1 or 1:n relationship between those two:

Base = declarative_base()

class A(Base):
    __tablename__ = 'a'

    id = Column(Integer, primary_key=True)

class B(Base):
    __tablename__ = 'b'

    id = Column(Integer, primary_key=True)
    a_id = Column(Integer, ForeignKey('a.id'))

    foobar = relationship('A')

    def __init__(self):
        self.foobar = A()

For a real-world example, read the ORM tutorial, where your class A is named User and B Address.

Upvotes: 1

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