On Friday, April 24, 2020 at 1:16:10 PM UTC-4, Jens Troeger wrote:
>
>
> If I understand you correctly, then the solution above is as good as it
> gets and SQLA doesn’t provide a builtin solution for what I’m trying to do?
>
There are so many hooks in SqlAlchemy, there may still be a more
Thanks Jonathan! Yes, all classes derive from the declarative base:
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base(metadata=MetaData(naming_convention={...}))
class Parent(Base):
...
class Child(Base):
...
If I understand you correctly, then the
Assuming you are using declarative, this is okay (
https://docs.sqlalchemy.org/en/14/orm/mapping_api.html?#sqlalchemy.orm.Mapper
)
Note this line:
A class which was mapped by the sqlalchemy.ext.declarative
So, here’s what I’m experimenting with and it seems to work:
@property
def children(self):
children = (getattr(self, r.key) for r in
self.__mapper__.relationships if r.target.name == "child")
return [c for c in children if c is not None]
I’m not sure if this is the
Thank you, Jonathan.
I’ve used SQLA’s association proxies before, I’ll take a look again.
You bring up a good point, though:
Ok, so this isn't a one-to-one relationship, but a many-to-many
> relationship.
>
That’s something I’ve been debating with myself for a while before I posted
here: the
On Friday, April 17, 2020 at 8:02:50 PM UTC-4, Jens Troeger wrote:
>
>
> Indeed, Child does have multiple parents…
>
Ok, so this isn't a one-to-one relationship, but a many-to-many
relationship.
I would opt for a 3 table structure:
Parent
Parent_2_Child
Child
The
Hi Jonathan,
The line you commented out from the example was either:
>
> children = relationship("Child")
>
> children = relationship("Child", back_populates="parent")
>
>
> both of those lines create an iterable list of all the Child objects on
> the `children`
>
Neither of them would work,
This departs a bit from the example, because you are caching the youngest
and oldest ids onto the Parent object. is that necessary for your usage?
> Now my question is: how can I introduce a set/list of all children on the
parent?
The line you commented out from the example was either:
