Many to Many - Association Object query based on extra association field - flask

Question

I have a many to many association Object relationship. The association object has an extra field for a timestamp. The idea is to only return the associated relationship if the timestamp of the association is within a specific time frame.
models.py
from rvt import db
from sqlalchemy_utils import IPAddressType
class ReportAssociation(db.Model):
id = db.Column(db.Integer, primary_key=True)
entity_id = db.Column(db.Integer, db.ForeignKey('entity.id'))
report_id = db.Column(db.Integer, db.ForeignKey('report_map.id'))
timestamp = db.Column(db.DateTime)
report_map = db.relationship('ReportMap', back_populates='entities')
entity = db.relationship('Entity', back_populates='report_maps')
__table_args__ = (
db.UniqueConstraint('entity_id', 'report_id', 'timestamp'),
)
def __repr__(self):
return f'ReportAssociation: {self.entity} {self.report_map} - {self.timestamp}'
class Entity(db.Model):
id = db.Column(db.Integer, primary_key=True)
ip_address = db.Column(IPAddressType, unique=True, nullable=False)
hostname = db.Column(db.String(64), index=True, nullable=True)
region = db.Column(db.String(32), index=True, nullable=True)
geo = db.Column(db.String(32), index=True, nullable=True)
city = db.Column(db.String(32), index=True, nullable=True)
asn = db.Column(db.String(8), index=True, nullable=True)
subnet_desc = db.Column(db.String(256), index=True, nullable=True)
report_maps = db.relationship('ReportAssociation', back_populates='entity', lazy="dynamic")
timestamp = db.Column(db.DateTime)
def __repr__(self):
return f'<Entity {self.ip_address}>'
class ReportMap(db.Model):
id = db.Column(db.Integer, primary_key=True)
pattern = db.Column(db.String(64), nullable=False, unique=True)
name = db.Column(db.String(32), nullable=False, unique=True)
short_name = db.Column(db.String(32), nullable=False, unique=True)
wiki_url = db.Column(db.String(128), nullable=True, unique=False)
entities = db.relationship('ReportAssociation', back_populates='report_map', lazy="dynamic")
def __repr__(self):
return f'<ReportMap {self.name}>'
The problem I am having is with the query. The following works.
>>> e = Entity.query.one()
>>> e
<Entity 101.98.10.156>
>>> for i in e.report_maps.all():
... print(i.timestamp)
...
2019-04-02 21:15:49.985126
2019-04-02 21:15:59.028121
>>> for i in e.report_maps.filter_by(timestamp='2019-04-02 21:15:59.028121'):
... print(i.timestamp)
...
2019-04-02 21:15:59.028121
The problem comes in when I try to use something like below
>>> for i in e.report_maps.filter(timestamp < '2019-04-02 21:15:59.028121'):
... print(i.timestamp)
...
Traceback (most recent call last):
File "<console>", line 1, in <module>
NameError: name 'timestamp' is not defined
Any help would be appreciated. Thanks

Answer 1

When you use filter method you must use ClassName.attribue so can use you last query like this:
e.report_maps.filter(Entity.timestamp < '2019-04-02 21:15:59.028121').all()