Cool, that's what I wanted to know. I didn't want to miss some function
that did this for me if it was there.
Thanks alot for the help!
Dan
On Wednesday, April 24, 2013 1:42:39 PM UTC-4, Michael Bayer wrote:
>
>
> On Apr 24, 2013, at 1:38 PM, dan <d...@inlet.geol.sc.edu <javascript:>>
> wrote:
>
> 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.
>
>
>
> well the issue of the pest_to_pesticide table and the unique entries in
> Pest are two separate things. since this is many to many, sure any number
> of Pests can be associated with any number of Pesticides, so to achieve
> this you of course need to work with an existing Pest entry and associate
> it as needed. Typically, if you know what Pest you want to work with, you
> look it up in the database, if its not there, you create it. The
> UniqueObject recipe is one way to make this more "invisible" but it isn't a
> requirement. Just to get things to work you might want to keep it simple
> and just do a "get_or_create_pest()" function, before turning it into
> something more transparent.
>
>
>
> 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> 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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>>
>>
>>
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