CODEWITHSUNDEEP
pythonpostgresqlsqlalchemy
Casey
Casey

Reputation: 2719

Save relational sqlalchemy object from a dict

I'm trying to save an object to a postgres database using sqlalchemy but am having problems. The below code works, but instead of saving a single instance of location 'Atlanta', and referring to multiple hotels via a foreign key, it is saving the location over and over in the locations table.

How can I set up my code so that I have a single entry 'Atlanta' in the locations table, with multiple hotels referring to that location?

Here are the relevant parts of my code:

class Hotel(Base):
    __tablename__ = 'hotels'

    id = Column(Integer, primary_key=True)
    hotelName = Column(String)
    standardRate = Column(Numeric(6, 2))
    govtRate = Column(Numeric(6, 2))
    standardAvailable = Column(Boolean, nullable=False)
    govtAvailable = Column(Boolean, nullable=False)
    arrive = Column(Date, nullable=False)
    depart = Column(Date, nullable=False)
    updated = Column(DateTime, default=datetime.datetime.utcnow, nullable=False)
    location_id = Column(Integer, ForeignKey('location.id'))
    location = relationship('Location')

class Location(Base):
    __tablename__ = 'location'
    id = Column(Integer, primary_key=True)
    city = Column(String, nullable=False)

def scrape(location, arrive, depart, hotelIDs):
    hotels = []
    for id in hotelIDs:
      hotels.append({
            'hotelName': hotelName,
            'standardRate': standardRate,
            'govtRate': govtRate,
            'standardAvailable': standardAvailable,
            'govtAvailable': govtAvailable,
            'arrive': dateToISO(arrive),
            'depart': dateToISO(depart),
            'location': Location(city='Atlanta')
            })
    return hotels

def save_hotel(item):
    session = db_setup()

    hotel = Hotel(**item)
    session.commit()

hotels = scrape("atlanta", "02/20/2016", "02/21/2016", hotelIDs)
for hotel in hotels:
    save_hotel(hotel)

Upvotes: 1

Views: 455

Answers (1)

Justin O Barber
Justin O Barber

Reputation: 11591

It appears that you are creating a new Location instance on every iteration of your for statement:

for id in hotelIDs:
    hotels.append({
        'hotelName': hotelName,
        'standardRate': standardRate,
        'govtRate': govtRate,
        'standardAvailable': standardAvailable,
        'govtAvailable': govtAvailable,
        'arrive': dateToISO(arrive),
        'depart': dateToISO(depart),
        'location': Location(city='Atlanta')  # <- new location instance here
        })

Rather, I believe you want to attach all hotels to a single location with something more like this:

location = Location(city='Atlanta')
# or if you already have Atlanta in your database:
# location = session.query(Location).filter_by(city='Atlanta').first() 

for id in hotelIDs:
    hotel = Hotel( ... )
    location.location.append(hotel)  # append hotel instance here
    ...

# now add to session and commit

Upvotes: 1

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