Using the collection_class=set is only going to work if I try to add the
same pest multiple times into pestList isn't it?
My situation is more along the lines that the pest table already has the
pest, and the pesticide I want to add also will have that pest, so I want
the entries in the pest_to_pesticide created. What currently happens is an
IntegrityError is thrown complaining that there is a duplicate pest entry.
On Wednesday, April 24, 2013 1:24:59 PM UTC-4, Michael Bayer wrote:
>
> pesttopesticide is maintained by relationship() as the "secondary" table,
> but the expectation is that rows in this table will be unique. if you are
> appending duplicate entries to "pestList" or "pesticide" you may want to
> use collection_class=set to maintain uniqueness in the collection.
>
>
> On Apr 24, 2013, at 12:51 PM, dan <d...@inlet.geol.sc.edu <javascript:>>
> wrote:
>
> I've got a many to many relationship with the association table. The issue
> I am running into is that a given pesticide entry may have a pest or pests
> already in the pest table. I don't want to add the pest since it will be a
> duplicate, however I still want the association of that pest to the
> pesticide done.
>
> I've looked at the Unique Object wiki, however I am not sure that solves
> my issue. Is there a way that SQLAlchemy can handle this, or do I need to
> manually build the entries in the PestToPesticide association table?
>
> Thanks!
>
> Dan
>
> PestToPesticide = Table('pest_to_pesticide', Base.metadata,
> Column('pesticide_id', Integer,
> ForeignKey('pesticide.row_id')),
> Column('pest_id', Integer,
> ForeignKey('pest.row_id'))
> )
> class Pesticide(Base):
> __tablename__ = 'pesticide'
> row_id =
> Column(Integer,primary_key=True)
> name = Column(String(64), unique=True)
>
> pestList =relationship("Pest",
> secondary=PestToPesticide, backref="pesticide")
>
> class Pest(object):
> row_id =
> Column(Integer,primary_key=True)
> name = Column(String(), unique=True)
>
>
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