Hello, I am using SQLAlchemy version 1.2.0b1
I created some mapped objects using the declarative style in SQLAlchemy. I
have a mapping called ThermafuserReading which has a composed primary key
made up of the Time_stamp column which is DateTime and ThermafuserId column
which is an Integer and also acts as a Foreign Key to another table called
Thermafuser. This is the definition of the class
class ThermafuserReading(Base):
"""Class to map to the Thermafuser Readings table in the HVAC DB"""
__tablename__ = 'Thermafuser_Reading'
_timestamp = Column('Time_stamp', DateTime, primary_key = True)
_thermafuserId = Column('ThermafuserId', Integer,
ForeignKey("Thermafuser.ThermafuserId"), primary_key = True)
_roomOccupied = Column('RoomOccupied', Boolean)
_zoneTemperature = Column('ZoneTemperature', Float)
_supplyAir = Column('SupplyAir', Float, nullable=True)
_airflowFeedback = Column('AirflowFeedback', Float, nullable=True)
_CO2Input = Column('CO2Input', Float, nullable=True)
_maxAirflow = Column('MaxAirflow', Float, nullable=True)
_minAirflow = Column('MinAirflow', Float, nullable=True)
_unoccupiedHeatingSetpoint = Column('UnoccupiedHeatingSetpoint', Float,
nullable=True)
_unoccupiedCoolingSetpoint = Column('UnoccupiedCoolingSetpoint', Float,
nullable=True)
_occupiedCoolingSetpoint = Column('OccupiedCoolingSetpoint', Float,
nullable=True)
_occupiedHeatingSetpoint = Column('OccupiedHeatingSetpoint', Float,
nullable=True)
_terminalLoad = Column('TerminalLoad', Float, nullable=True)
#Relationship between Thermafuser Reading and Thermafuser
_thermafuser = relationship("Thermafuser", back_populates =
"_thermafuserReadings", cascade = "all, delete-orphan", single_parent = True)
I am creating a session in the following way
sqlengine =
sqlalchemy.create_engine("mysql+mysqldb://user:password@localhost:3306/HVAC")
Session = sessionmaker(bind=sqlengine)
session = Session()
At some point in my code I am creating a list called readings of
Thermafuser Readings and adding such list the session via
session.add_all(readings)
This are some example elements printed from the list readings:
for reading in readings:
print(reading, mapper.identity_key_from_instance(reading))
<ThermafuserReading(thermafuserId = '1', timestamp = '2016-12-31 23:40:00')>
(<class '__main__.ThermafuserReading'>, (datetime.datetime(2016, 12, 31, 23,
40), 1))
<ThermafuserReading(thermafuserId = '1', timestamp = '2016-12-31 23:45:00')>
(<class '__main__.ThermafuserReading'>, (datetime.datetime(2016, 12, 31, 23,
45), 1))
<ThermafuserReading(thermafuserId = '1', timestamp = '2016-12-31 23:50:00')>
(<class '__main__.ThermafuserReading'>, (datetime.datetime(2016, 12, 31, 23,
50), 1))
<ThermafuserReading(thermafuserId = '1', timestamp = '2016-12-31 23:55:00')>
(<class '__main__.ThermafuserReading'>, (datetime.datetime(2016, 12, 31, 23,
55), 1))
<ThermafuserReading(thermafuserId = '1', timestamp = '2017-01-01 00:00:00')>
(<class '__main__.ThermafuserReading'>, (datetime.datetime(2017, 1, 1, 0, 0),
1))
So far so go, the problem arises when I add readings to the session via
session.add_all(readings). I only get the last element in my list added,
e.g.
for new in session.new:
print(new, mapper.identity_key_from_instance(new_object))
<ThermafuserReading(thermafuserId = '1', timestamp = '2017-01-01
00:00:00')> (<class '__main__.ThermafuserReading'>,
(datetime.datetime(2017, 1, 1, 0, 0), 1))
Why is this behavior? I have a test code and the test data in case its
needed to reproduce this behavior
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
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