I'm using flask-sqlalchemy, this is not the first relations that i've built, but for some reason it gives me an error when i start flask:
sqlalchemy.exc.InvalidRequestError: One or more mappers failed to initialize - can't proceed with initialization of other mappers. Triggering mapper: 'mapped class User->users'. Original exception was: 'Table' object has no attribute 'sender_id'
These are two models that i'm trying to connect via ForeignKeys:
User:
class User(UserMixin, db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(64), index=True, unique=True)
email = db.Column(db.String(120), index=True, unique=True)
password_hash = db.Column(db.String(128))
about_me = db.Column(db.String(140))
last_seen = db.Column(db.DateTime, default=datetime.utcnow)
#relations
posts = db.relationship('Post', back_populates='author', lazy='dynamic')
messages_sent = db.relationship('Message', foreign_keys='messages.sender_id',
back_populates='author', lazy='dynamic')
messages_received = db.relationship('Message', foreign_keys='messages.recipient_id',
back_populates='recipient', lazy='dynamic')
last_message_read_time = db.Column(db.DateTime)
followed = db.relationship(
'User', secondary=followers,
primaryjoin=(followers.c.follower_id == id),
secondaryjoin=(followers.c.followed_id == id),
backref=db.backref('followers', lazy='dynamic'), lazy='dynamic')
def __repr__(self):
return '<User {}>'.format(self.username)
And Messsage:
class Message(db.Model):
__tablename__ = 'messages'
id = db.Column(db.Integer, primary_key=True)
sender_id = db.Column(db.Integer, db.ForeignKey('users.id'))
recipient_id = db.Column(db.Integer, db.ForeignKey('users.id'))
body = db.Column(db.String(140))
timestamp = db.Column(db.DateTime, index=True, default=datetime.utcnow)
#relations
author = db.relationship('User', back_populates='messages_sent', lazy='dynamic')
recipient = db.relationship('User', back_populates='messages_received', lazy='dynamic')
def __repr__(self):
return '<Message {}>'.format(self.body)
I've checked the database itself and it certainly has sender_id in the correct table, tried to change "foreign_keys" parameter to directly name of model Message.sender... Tried to change parameters of lazy on those relations. It still gives me same error.
This is subtle but messages in this case is a table so columns are referenced off of c, like messages.c.sender_id. To use the column of the model class (the mapped class) you would do Message.sender_id.
So...
messages_sent = db.relationship('Message', foreign_keys='messages.c.sender_id',
back_populates='author', lazy='dynamic')
# OR
messages_sent = db.relationship('Message', foreign_keys='Message.sender_id',
back_populates='author', lazy='dynamic')
There is some information here but it doesn't explain the table vs class situation: handling-multiple-join-paths I think I would just use ORM style references until you are more comfortable and then you could use table references if needed.
I have defined two model with relation between them as below:
class Role(db.Model):
__tablename__ = 'roles'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(40), nullable=False, unique=False)
db.relationship('User', backref='role', lazy='dynamic')
def __init__(self, name):
self.name = name
def __repr__(self):
return f'<Role id={self.id} name={self.name}>'
class User(db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(40), unique=True)
password = db.Column(db.String(40), unique=True)
role_id = db.Column(db.Integer, db.ForeignKey('roles.id'))
def __init__(self, username, password, role_id):
self.username = username
self.password = password
self.role_id = role_id
def __repr__(self):
return f'<User id={self.id} username={self.username} password={self.password}>'
Then inside shell I created entries as below:
> admin_role = Role('Admin')
> db.session.add(admin_role)
> db.session.commit()
> admin_user = User('adminusername', 'adminpassword',admin_role.id)
> db.session.add(admin_user)
> db.session.commit()
When I try to query model I get perfect result:
>>> admin_role = Role.query.first()
>>> admin_user = User.query.first()
>>> print(admin_role)
<Role id=1 name=Admin>
>>> print(admin_user)
<User id=1 username=adminusername password=adminpassword>
But when I try to access relation
print(admin_role.users)
print(admin_user.role)
I get errors Role object has no attribute users and User object has no attribute role respectively.
Typo? You have to assign db.relationship() instance to a variable.
class Role(db.Model):
__tablename__ = 'roles'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(40), nullable=False, unique=False)
- db.relationship('User', backref='role', lazy='dynamic')
+ users = db.relationship('User', backref='role', lazy='dynamic')
sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join condition between parent/child tables on relationship Location.changes_in_location - there are multiple foreign key paths linking the tables. Specify the 'foreign_keys' argument, providing a list of those columns which should be counted as containing a foreign key reference to the parent table.
Someone else had asked about this error before, but the cause seems to have been different. I'm trying to track product movements between warehouses. This is the code for my models file:
from inventory import db
from datetime import datetime
class Product(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50), unique=True, nullable=False)
product_movements = db.relationship('Movement', backref='item', lazy=True)
def __repr__(self):
return f"{self.name} added."
class Location(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50), unique=True, nullable=False)
changes_in_location = db.relationship('Movement', backref='location', lazy=True)
def __repr__(self):
return f"{self.location} added."
class Movement(db.Model):
id = db.Column(db.Integer, primary_key=True)
product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
product = db.Column(db.String(50), nullable=False)
from_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
from_location = db.Column(db.String(50))
to_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
to_location = db.Column(db.String(50))
quantity = db.Column(db.Integer, nullable=False)
timestamp = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
def __repr__(self):
return f"{self.quantity} units of {self.product} moved from {self.from_location} to {self.to_location} at {self.timestamp}."
You should be adding the relationship in models for multiply relation and specify the ForeignKey and primaryjoin in the relationship.
lass Location(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50), unique=True, nullable=False)
from_locations = db.relationship('Movement', backref='location', lazy=True, primaryjoin='Movement.from_location_id == Location.id')
to_location = db.relationship('Movement', backref='location', lazy=True, primaryjoin='Movement.to_location_id == Location.id')
def __repr__(self):
return f"{self.location} added."
class Movement(db.Model):
id = db.Column(db.Integer, primary_key=True)
product_id = db.Column(db.Integer, db.ForeignKey('product.id'))
product = db.Column(db.String(50), nullable=False)
from_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
from_location = db.Column(db.String(50))
to_location_id = db.Column(db.Integer, db.ForeignKey('location.id'))
to_location = db.Column(db.String(50))
quantity = db.Column(db.Integer, nullable=False)
timestamp = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
from_location = db.relationship('Location', backref='from_locations', lazy=True, foreign_keys=[from_location_id])
to_location = db.relationship('Location', backref='to_locations', lazy=True, foreign_keys=[to_location_id])
def __repr__(self):
return f"{self.quantity} units of {self.product} moved from {self.from_location} to {self.to_location} at {self.timestamp}."
I'm sory for this newby question, but I can't figure it out for a couple days and it is driving me nuts.
I'm building a small project in order to learn flask, SqlAlchemy and Postrges.
I have major problems with declaring classes in SqlAlchemy. I have already simplified models by removing all many-to-many relationships. However, now I have new problems even with one-to many relationships, although I think I have tried all the possible options. Maybe there's a typo that I keep on overlooking, or I don't grasp something fundamental. Please let me know...
So, I have classes declared as follows in my models.py:
#login_manager.user_loader
def load_user(user_id):
return User.query.get(int(user_id))
class User(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key = True)
username = db.Column(db.String(20), unique=True, nullable=False)
email = db.Column(db.String(120), unique=True, nullable=False)
password = db.Column(db.String(60), nullable=False)
date_registered = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
role = db.Column(db.Integer, nullable=False)
role_exp_date = db.Column(db.DateTime)
#o2o
personal_datas = db.relationship('PersonalData', uselist=False, backref='user', lazy=True)
persons = db.relationship('Person', uselist=False, backref='user', lazy=True)
#o2m
posts = db.relationship('Post', backref='author', lazy=True)
comments = db.relationship('PostComment', backref='author', lazy=True)
projects_owned = db.relationship('ConstrProject', backref='owner', lazy=True)
attachments = db.relationship('Attachment', backref='author', lazy=True)
def __repr__(self):
return f"{self.username} ({self.email})"
class PersonalData(db.Model):
id = db.Column(db.Integer, primary_key = True)
date_birth = db.Column(db.DateTime)
image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
interests = db.Column(db.Text)
experties = db.Column(db.Text) #Потом сделать отдельную таблицу...
#o2o
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
#o2m
class Person(db.Model):
id = db.Column(db.Integer, primary_key = True)
first_name = db.Column(db.String(30), nullable=False)
middle_name = db.Column(db.String(40), nullable=False)
last_name = db.Column(db.String(60), nullable=False)
email = db.Column(db.String(120))
license = db.Column(db.String(120))
address = db.Column(db.String(240))
telephone = db.Column(db.String(30))
#o2o
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
#o2m
signers = db.relationship('Signer', backref='person', lazy=True)
def __repr__(self):
return f"{self.last_name.Capitalize} {self.first_name[0].Upper}. {self.middle_name[0].Upper}."
class ConstrProject(db.Model):
__tablename__ = 'constrproject'
id = db.Column(db.Integer, primary_key = True)
name = db.Column(db.String(120), nullable=False, default='New Project')
full_title = db.Column(db.Text, default='New Project')
notes = db.Column(db.Text)
public = db.Column(db.Boolean, default=True) #? check expamples
date_created = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
date_last_edit = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
document_template = db.Column(db.Integer, nullable=False, default=1) #later to m2m
print_settings = db.Column(db.Integer, nullable=False, default=1) #later to m2m
address = db.Column(db.String(240))
#o2m
documents = db.relationship('Document', backref='project', lazy=True)
#m2o
owner_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False) #+ #default = CurrentUser
developer_id = db.Column(db.Integer, db.ForeignKey('company.id'))
main_contractor_id = db.Column(db.Integer, db.ForeignKey('company.id'))
architect_id = db.Column(db.Integer, db.ForeignKey('company.id'))
subcontractor_id = db.Column(db.Integer, db.ForeignKey('company.id'))
other_id = db.Column(db.Integer, db.ForeignKey('company.id'))
developer = db.relationship('Company', foreign_keys=[developer_id], back_populates='constr_projects_developed')
main_contractor = db.relationship('Company', foreign_keys=[main_contractor_id], back_populates='constr_projects_main_contracts')
architect = db.relationship('Company', foreign_keys=[architect_id], back_populates='constr_projects_architect')
subcontractor = db.relationship('Company', foreign_keys=[subcontractor_id], back_populates='constr_projects_subcontracts')
other = db.relationship('Company', foreign_keys=[other_id], back_populates='constr_projects_other')
tech_control_reps_id = db.Column(db.Integer, db.ForeignKey('signer.id'), nullable=False)
main_contractor_reps_id = db.Column(db.Integer, db.ForeignKey('signer.id'), nullable=False)
architect_reps_id = db.Column(db.Integer, db.ForeignKey('signer.id'), nullable=False)
subcontractor_reps_id = db.Column(db.Integer, db.ForeignKey('signer.id'), nullable=False)
other_reps_id = db.Column(db.Integer, db.ForeignKey('signer.id'), nullable=False)
tech_control_reps = db.relationship('Signer', foreign_keys=[tech_control_reps_id], back_populates='tech_control_projects')
main_contractor_reps = db.relationship('Signer', foreign_keys=[main_contractor_reps_id], back_populates='main_contractor_projects')
architect_reps = db.relationship('Signer', foreign_keys=[architect_reps_id], back_populates='architect_projects')
subcontractor_reps = db.relationship('Signer', foreign_keys=[subcontractor_reps_id], back_populates='subcontractor_projects')
other_reps = db.relationship('Signer', foreign_keys=[other_reps_id], back_populates='others_projects')
def __repr__(self):
return f"Site: {self.name}, (id{self.id})"
class Signer(db.Model):
id = db.Column(db.Integer, primary_key = True)
decree = db.Column(db.String(120))
job_title = db.Column(db.String(120))
date_duty_start = db.Column(db.DateTime)
date_duty_end = db.Column(db.DateTime)
#o2m
person_id = db.Column(db.Integer, db.ForeignKey('person.id'), nullable=False)
company_id = db.Column(db.Integer, db.ForeignKey('company.id'), nullable=False)
#m2o
tech_control_projects = db.relationship('ConstrProject', back_populates='tech_control_reps')
main_contractor_projects = db.relationship('ConstrProject', back_populates='main_contractor_reps')
architect_projects = db.relationship('ConstrProject', back_populates='architect_reps')
subcontractor_projects = db.relationship('ConstrProject', back_populates='subcontractor_reps')
others_projects = db.relationship('ConstrProject', back_populates='other_reps')
def __repr__(self):
return f"{self.job_title} as per {self.decree}." #название компании как подтянуть
class Company(db.Model):
id = db.Column(db.Integer, primary_key = True)
name = db.Column(db.String(60))
full_title = db.Column(db.String(240))
tin = db.Column(db.Integer)
kpp = db.Column(db.Integer)
ogrn = db.Column(db.Integer)
email = db.Column(db.String(120))
address = db.Column(db.String(240))
telephone = db.Column(db.String(30))
#o2m
license_number = db.Column(db.String(40), nullable = False)
license_date_issued = db.Column(db.DateTime)
license_category = db.Column(db.String(120), default = '2nd')
license_issued_by = db.Column(db.String(120))
license_issued_by_tin = db.Column(db.Integer)
license_issued_by_kpp = db.Column(db.Integer)
license_issued_by_ogrn = db.Column(db.Integer)
signers = db.relationship('Signer', backref='company', lazy=True)
constr_projects_developed = db.relationship('ConstrProject', back_populates='developer')
constr_projects_main_contracts = db.relationship('ConstrProject', back_populates='main_contractor')
constr_projects_architect = db.relationship('ConstrProject', back_populates='architect')
constr_projects_subcontracts = db.relationship('ConstrProject', back_populates='subcontractor')
constr_projects_other = db.relationship('ConstrProject', back_populates='other')
def __repr__(self):
return f"{self.name}"
class Post(db.Model):
id = db.Column(db.Integer, primary_key = True)
title = db.Column(db.String(100), nullable=False)
date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
content = db.Column(db.Text, nullable=False)
#o2m
comments = db.relationship('PostComment', backref='Post', lazy=True)
#m2o
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
def __repr__(self):
return f"Post('{self.title}', '{self.date_posted}')"
class PostComment(db.Model):
id = db.Column(db.Integer, primary_key = True)
date_posted = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
content = db.Column(db.Text, nullable=False)
#m2o
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
post_id = db.Column(db.Integer, db.ForeignKey('post.id'), nullable=False)
def __repr__(self):
return f"Comment('{self.id}', '{self.date_posted}')"
class Document(db.Model):
id = db.Column(db.Integer, primary_key = True)
type = db.Column(db.String(60), nullable=False, default='АОСР')
date_last_edit = db.Column(db.DateTime, nullable=False, default=datetime.utcnow)
notes = db.Column(db.Text)
public = db.Column(db.Boolean, default=True)
number = db.Column(db.String(20), nullable=False)
date = db.Column(db.DateTime, default=datetime.utcnow)
job_name = db.Column(db.Text) #? обязательный? на каком этапе делать проверку?
job_place = db.Column(db.String(200))
date_job_start = db.Column(db.DateTime, default=datetime.utcnow)
date_job_end = db.Column(db.DateTime, default=datetime.utcnow)
regulations = db.Column(db.Text)
next_job_allowed = db.Column(db.String(240))
attachments_user_defined = db.Column(db.Text)
#o2m
attachments = db.relationship('Attachment', backref='document', lazy=True)
#m2o
project_id = db.Column(db.Integer, db.ForeignKey('constrproject.id'), nullable=False)
author_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
#m2m
arch_docs = db.Column(db.Text)
building_materials = db.Column(db.Text)
work_drawings = db.Column(db.Text)
def __repr__(self):
return f"АОСР ('{self.number}', '{self.job_name} {self.job_place}', '{self.project}' )"
class Attachment(db.Model):
id = db.Column(db.Integer, primary_key = True)
type_of_document = db.Column(db.String(60), nullable=False, default="QAC")
number = db.Column(db.String(50), nullable=False)
date = db.Column(db.DateTime)
date_valid_start = db.Column(db.DateTime)
date_valid_end = db.Column(db.DateTime)
contents = db.Column(db.Text)
type_of_file = db.Column(db.String(10), nullable=False, default = 'jpg')
image_file = db.Column(db.String(20), nullable=False)
#m2o
author_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
document_id = db.Column(db.Integer, db.ForeignKey('document.id'), nullable=False)
def __repr__(self):
if self.text:
return f'{self.text}'
return f'+{self.type_of_document} id{self.id} ({self.type_of_file})'
I cannot understand why, when I try to create an instance of a "Document"
I get errors like this:
sqlalchemy.exc.AmbiguousForeignKeysError: Could not determine join
condition between parent/child tables on relationship
Signer.tech_control_projects - there are multiple foreign key paths
linking the tables. Specify the 'foreign_keys' argument, providing a
list of those columns which should be counted as containing a foreign
key reference to the parent table.
or
sqlalchemy.exc.InvalidRequestError: When initializing mapper
Mapper|ConstrProject|constrproject, expression 'tech_control_reps_id'
failed to locate a name ("name 'tech_control_reps_id' is not
defined"). If this is a class name, consider adding this
relationship() to the class
after both dependent classes have been defined.
I haven't even tried to create these classes. Adding "foreign_keys" doesn't seem to help either. all relationships declared as strings. I tried to use lambda's also without success.
Nevertheless moving the order of class declearations alters the error messages i get...
I cannot find any good examples (resources) of more complicated databases with multiple many-to-many and one-to-many relationships in Each class. Usually examples are very basic and obvious.
So I would really appreciate if you post links to such projects or tutorials.
I wanted to learn some of it myself so I created a working example with one-to-one and multiple one-to-many relationships based on your code (User, Person, Post and Comment classes). I hope it will be a good (simple but not trivial) example for you.
'''SQLAlchemy one-to-one and one-to-many SSCCE'''
import sqlalchemy
import sqlalchemy.ext.declarative
from passlib.hash import pbkdf2_sha256
Base = sqlalchemy.ext.declarative.declarative_base()
class User(Base):
__tablename__ = 'users'
user_id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True)
username = sqlalchemy.Column(sqlalchemy.String(20), unique=True, nullable=False)
email = sqlalchemy.Column(sqlalchemy.String(120), unique=True, nullable=False)
password = sqlalchemy.Column(sqlalchemy.String(100), nullable=False)
registered = sqlalchemy.Column(
sqlalchemy.DateTime(timezone=True),
nullable=False,
server_default=sqlalchemy.func.now()
)
#o2o
person = sqlalchemy.orm.relationship(
'Person',
uselist=False,
back_populates='user',
lazy='joined'
)
#o2m
posts = sqlalchemy.orm.relationship('Post', back_populates='user')
comments = sqlalchemy.orm.relationship('Comment', back_populates='user')
def __repr__(self):
return f'{self.username} ({self.email})'
class Person(Base):
__tablename__ = 'persons'
person_id = sqlalchemy.Column(
sqlalchemy.Integer,
sqlalchemy.ForeignKey('users.user_id'),
primary_key=True
)
first_name = sqlalchemy.Column(sqlalchemy.String(30), nullable=False)
middle_name = sqlalchemy.Column(sqlalchemy.String(40), nullable=False)
last_name = sqlalchemy.Column(sqlalchemy.String(60), nullable=False)
#o2o
user = sqlalchemy.orm.relationship('User', back_populates='person', lazy='joined')
def __repr__(self):
return (
f'{self.last_name.upper()}'
f' {self.first_name[:1].upper()}.'
f' {self.middle_name[:1].upper()}.'
)
class Post(Base):
__tablename__ = 'posts'
post_id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True)
title = sqlalchemy.Column(sqlalchemy.String(100), nullable=False)
posted = sqlalchemy.Column(
sqlalchemy.DateTime(timezone=True),
nullable=False,
server_default=sqlalchemy.func.now()
)
content = sqlalchemy.Column(sqlalchemy.Text, nullable=False)
#o2m
comments = sqlalchemy.orm.relationship('Comment', back_populates='post')
#m2o
user_id = sqlalchemy.Column(
sqlalchemy.Integer,
sqlalchemy.ForeignKey('users.user_id'),
nullable=False
)
user = sqlalchemy.orm.relationship('User', uselist=False, back_populates='posts', lazy='joined')
def __repr__(self):
return f'Post({self.title!r}, {self.posted!r})'
class Comment(Base):
__tablename__ = 'comments'
comment_id = sqlalchemy.Column(sqlalchemy.Integer, primary_key=True)
posted = sqlalchemy.Column(
sqlalchemy.DateTime(timezone=True),
nullable=False,
server_default=sqlalchemy.func.now()
)
content = sqlalchemy.Column(sqlalchemy.Text, nullable=False)
#m2o
user_id = sqlalchemy.Column(
sqlalchemy.Integer,
sqlalchemy.ForeignKey('users.user_id'),
nullable=False
)
user = sqlalchemy.orm.relationship(
'User',
uselist=False,
back_populates='comments',
lazy='joined'
)
post_id = sqlalchemy.Column(
sqlalchemy.Integer,
sqlalchemy.ForeignKey('posts.post_id'),
nullable=False
)
post = sqlalchemy.orm.relationship(
'Post',
uselist=False,
back_populates='comments',
lazy='joined'
)
def __repr__(self):
return f'Comment({self.comment_id!r}, {self.posted!r})'
def main():
engine = sqlalchemy.create_engine(
'postgresql+psycopg2:///stack',
echo=True,
server_side_cursors=True,
use_batch_mode=True
)
Base.metadata.create_all(engine)
Session = sqlalchemy.orm.sessionmaker(bind=engine)
session = Session()
session.commit()
try:
the_user = session.query(User).filter(User.username == 'example').one()
except sqlalchemy.orm.exc.NoResultFound:
the_user = User(
username='example',
email='example#example.com',
password=pbkdf2_sha256.hash('correct horse battery staple')
)
the_user.person = Person(first_name='Ex', middle_name='', last_name='Ample')
session.add(the_user)
print(the_user)
print(the_user.person)
if not the_user.posts:
the_user.posts.append(Post(title='First post', content='Lorem ipsum'))
session.commit()
print(the_user.posts[0])
if not the_user.posts[0].comments:
the_user.posts[0].comments.append(Comment(content='Me too', user=the_user))
session.commit()
print(the_user.posts[0].comments[0])
if __name__ == '__main__':
main()
Several comments:
I don't think it is easy to have foreign-keys both ways for a mandatory one-to-one relationship.
I made both User and Person use the same id numbers, as they are one-to-one.
I made the PostgreSQL now() as the default value for timestamps, instead of client-side utcnow.
I made the timestamps use "timestamp with timezone" type - the "timestamp" type (without timezone) is an abomination.
"user" is a bad name for a table, as this is also a keyword in PostgreSQL, so I changed it to "users". Other tables also changed to plural form for consistency.
A secure password storage is a must.
I used back_populates consistently, as it is more explicit and works better with static code analyzers than backref.
I do have these 2 calsses als DB models trying to buidl a 1 to many relation:
class User(db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(255), index=True) #, unique=True)
firstname = db.Column(db.String(50))
lastname = db.Column(db.String(50))
bt_ids = db.relationship("BT", order_by="BT.id", backref="user")
class BT(db.Model):
__tablename__ = 'bt'
id = db.Column(db.Integer, primary_key=True)
bt_id = db.Column(db.String(255), unique=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
user = db.relationship("User", backref=db.backref('bt', order_by=id))
But I guess I do not really understand the way of setting up the relationships:
ArgumentError: Error creating backref 'user' on relationship 'User.bt_ids': property of that name exists on mapper 'Mapper|BT|bt'
Any ideas?
EDIT
I actually wanted to achive something like the example of SQLAlchemy
class User(Base):
__tablename__ = 'users'
id = Column(Integer, Sequence('user_id_seq'), primary_key=True)
name = Column(String(50))
fullname = Column(String(50))
password = Column(String(12))
**addresses = relationship("Address", order_by="Address.id", backref="user")**
def __repr__(self):
return "<User(name='%s', fullname='%s', password='%s')>" % (
self.name, self.fullname, self.password)
class Address(Base):
__tablename__ = 'addresses'
id = Column(Integer, primary_key=True)
email_address = Column(String, nullable=False)
user_id = Column(Integer, ForeignKey('users.id'))
**user = relationship("User", backref=backref('addresses', order_by=id))**
def __repr__(self):
return "<Address(email_address='%s')>" % self.email_address
There is already a FK relation between User and BT through user_id property so you can't create another relation named user in BT.
class User(db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(255), index=True) #, unique=True)
firstname = db.Column(db.String(50))
lastname = db.Column(db.String(50))
bts = db.relationship("BT", order_by="BT.id", backref="user")
class BT(db.Model):
__tablename__ = 'bt'
id = db.Column(db.Integer, primary_key=True)
bt_id = db.Column(db.String(255), unique=True)
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
Now I got it...
This was wrong:
user = db.relationship("User", backref=db.backref('bt_ids', order_by=id))
Now it works!