The problem I face is the following: in the following block of code you can see that I want to separate the id, created_on and updated_on attributes so that I follow the Don't Repeat Yourself (DRY) principle.
# Used to generalize a default database model with an ID
class IdentifierMixin(object):
id = db.Column(db.Integer, primary_key=True)
# Used to generalize timestamps on the default database model
class TimestampMixin(object):
created_on = db.Column(db.DateTime, server_default=db.func.now())
updated_on = db.Column(db.DateTime, server_default=db.func.now(),
onupdate=db.func.now())
# The many-to-many relationships
users_roles = db.Table('users_roles',
db.Column('user_id', db.Integer(), db.ForeignKey('user.id')),
db.Column('role_id', db.Integer(), db.ForeignKey('role.id')))
class User(declarative_base(), IdentifierMixin, TimestampMixin, UserMixin):
__tablename__ = 'user'
# Relationships
roles = db.relationship('Role', secondary=users_roles,
backref=db.backref('users', lazy='dynamic'))
uploads = db.relationship('Upload', backref='uploader', lazy='dynamic')
email = db.Column(db.String(100), nullable=False, unique=True)
username = db.Column(db.String(40), nullable=True, unique=True)
password = db.Column(db.String, nullable=False)
authenticated = db.Column(db.Boolean, default=False)
# True, as all users are active
def is_active(self):
return True
# Return the email address to satisfy Flask-Login's requirements
def get_id(self):
return self.email
# Return the authenticated parameter
def is_authenticated(self):
return self.authenticated
# False, anonymous users are not supported
def is_anonymous(self):
return False
def __repr__(self):
if self.username is not None:
return '<User %r>' % self.username
else:
return '<User %r>' % self.email
class Role(declarative_base(), IdentifierMixin, RoleMixin):
__tablename__ = 'role'
name = db.Column(db.String(80), unique=True)
description = db.Column(db.String(255))
However, it seems that the id attribute (inherited from the IdentifierMixin mixin) cannot be found:
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column 'users_roles.user_id' could not find table 'user' with which to generate a foreign key to target column 'id'
Can someone please explain what I am doing wrong? I would appriciate it immensely. With regards, Tim.
Related
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'm trying to add RBAC to my existing flask application where I already have 2 models which describe User and Post model respectively. Here is my code:
# models.py
from datetime import datetime
from rpd_site import db, login_manager
from flask_login import UserMixin
# []
#login_manager.user_loader
def load_user(user_id):
return User.query.get(int(user_id))
# Main site account table
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)
image_file = db.Column(db.String(20), nullable=False, default='default.jpg')
password = db.Column(db.String(60), nullable=False)
confirmed = db.Column(db.Boolean, nullable=False, default=0)
posts = db.relationship('Post', backref='author', lazy=True)
def __repr__(self):
return f"User('{self.username}', '{self.email}', '{self.confirmed}')"
# Posts table
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.now) # current local time instead of .utcnow
content = db.Column(db.Text, nullable=False)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'), nullable=False)
image_file = db.Column(db.String(20), nullable=False, default='default_post.png')
def __repr__(self):
return f"Post('{self.title}', '{self.date_posted}', '{self.content[:15]}')"
When I tried add all missing code from here I faced with lots of errors. Especially I'm not sure if I should import UserMixin from flask_rbac or from flask_login.
Help me to understand how can I upgrade my DB with RBAC functionality.
This is a very broad question, I'll try to give you a minimum code so that you can achieve RBAC. Below example uses Flask-security.
from app import db
from flask_security import RoleMixin, UserMixin
# may to many association table between User and Role
roles_users = db.Table(
'roles_users',
db.Column('user_id', db.Integer(), db.ForeignKey('user.id')),
db.Column('role_id', db.Integer(), db.ForeignKey('role.id'))
)
class Role(db.Model, RoleMixin):
__tablename__ = 'role'
id = db.Column(db.Integer(), primary_key=True)
name = db.Column(db.String(50), unique=True)
def __str__(self):
return self.name
class User(db.Model, UserMixin):
__tablename__ = 'user'
id = db.Column(db.Integer, primary_key=True)
email = db.Column(db.String(50), unique=True)
password = db.Column(db.String(255))
roles = db.relationship('Role', secondary=roles_users,
backref=db.backref('users', lazy='joined'))
def __str__(self):
return self.email
You either migrate or create the DB based on above Models. The above will be sufficient for you to either perform back-end operation for RDBC or at view level.
You can then assign roles to each user easily using below link.
Flask-security create role,user and linking user_id to role_id
If you want to perform RBAC at view, follow below.
from flask_security import login_required, roles_accepted
#app.route('/a_restricted_view/')
#login_required
#roles_accepted('role_one', 'role_two')
def a_restricted_view():
return "I am only visible to users with role_one and role_two"
So, I have been getting a lot of errors with SQLAlchemy from Flask and so far nothing I have found online has fixed it, only caused further errors to appear. My current model code is here:
class User(db.Model):
__tablename__ = "users"
id = db.Column(db.Integer, primary_key=True)
nickname = db.Column(db.String(64), index=True, unique=True)
email = db.Column(db.String(120), unique=True, nullable=False)
posts = db.relationship('Post', back_populates='author', lazy='dynamic',
primaryjoin='User.id == Post.user_id')
created_at = db.Column(db.DateTime, default=datetime.datetime.utcnow())
#property
def is_authenticated(self):
return True
#property
def is_active(self):
return True
#property
def is_anonymous(self):
return False
def get_id(self):
return str(self.id)
def __repr__(self):
return "<User %r>" % (self.nickname)
class Post(db.Model):
__tablename__ = 'post'
id = db.Column(db.Integer, primary_key=True)
body = db.Column(db.String(140))
timestamp = db.Column(db.DateTime)
user_id = db.Column(db.Integer, db.ForeignKey('user.id'))
def __repr__(self):
return '<Post %r>' % (self.body)
My current error with this code is:
sqlalchemy.exc.NoReferencedTableError: Foreign key associated with column 'post.user_id' could not find table 'user' with which to generate a foreign key to target column 'id'
I am at a complete loss as to what I'm doing wrong and why it is that no other solution has worked for me.
user.id needs to be users.id in your Post model:
user_id = db.Column(db.Integer, db.ForeignKey('users.id'))
So I created a basic Flask-User app with multiple roles and datastructure like this:
class User(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
active = db.Column('is_active', db.Boolean(), nullable=False, server_default='0')
first_name = db.Column(db.String(50), nullable=False, default='')
last_name = db.Column(db.String(50), nullable=False, default='')
email = db.Column(db.String(255), nullable=False, unique=True)
confirmed_at = db.Column(db.DateTime())
# Relationships
user_auth = db.relationship('UserAuth', uselist=False)
roles = db.relationship('Role', secondary='user_roles',
backref=db.backref('users', lazy='dynamic'))
def is_active(self):
return self.active
class UserAuth(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer(), db.ForeignKey('user.id', ondelete='CASCADE'))
# User authentication information
username = db.Column(db.String(50), nullable=False, unique=True)
password = db.Column(db.String(255), nullable=False, default='')
# Relationships
user = db.relationship('User', uselist=False)
def hash_password(self, password):
self.password_hash = pwd_context.encrypt(password)
def verify_password(self, password):
return pwd_context.verify(password, self.password_hash)
class Role(db.Model):
id = db.Column(db.Integer(), primary_key=True)
name = db.Column(db.String(50), unique=True)
class UserRoles(db.Model):
id = db.Column(db.Integer(), primary_key=True)
user_id = db.Column(db.Integer(), db.ForeignKey('user.id', ondelete='CASCADE'))
role_id = db.Column(db.Integer(), db.ForeignKey('role.id', ondelete='CASCADE'))
I try to show it in Flask-Admin:
class AdminView(ModelView):
def is_accessible(self):
access = current_user.is_authenticated and current_user.has_role('admin')
return access
admin = Admin(app, name='My Admin', template_mode='bootstrap3')
admin.add_view(AdminView(User, db.session))
admin.add_view(AdminView(UserAuth, db.session))
admin.add_view(AdminView(Role, db.session))
admin.add_view(AdminView(UserRoles, db.session))
Why It shows in such a strange manner:
And how to see and be able to edit user roles when editing a user?
You have not defined a suitable string representation for instances of your UserAuth class. A suitable example would be:
class UserAuth(db.Model, UserMixin):
id = db.Column(db.Integer, primary_key=True)
user_id = db.Column(db.Integer(), db.ForeignKey('user.id', ondelete='CASCADE'))
# User authentication information
username = db.Column(db.String(50), nullable=False, unique=True)
password = db.Column(db.String(255), nullable=False, default='')
# Relationships
user = db.relationship('User', uselist=False)
def hash_password(self, password):
self.password_hash = pwd_context.encrypt(password)
def verify_password(self, password):
return pwd_context.verify(password, self.password_hash)
def __str__(self):
return unicode(self).encode('utf-8')
def __unicode__(self):
return self.username
This needs to be done for all your models.
I'm developing a web app with python and flask. I use Flask, SQLAlchemy and PostgreSQL for development. I have many-to-one related models. By this models one company can have many users but each user can only have one company.
models.py
class Company(ResourceMixin, db.Model):
__tablename__ = 'companies'
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(100), unique=True, index=True,
nullable=False, server_default='')
phone = db.Column(db.String(24))
email = db.Column(db.String(255), index=True)
address = db.Column(db.String(255))
# Relations
users = db.relationship('User', backref='company')
class User(UserMixin, ResourceMixin, db.Model):
__tablename__ = 'users'
id = db.Column(db.Integer, primary_key=True)
# User details
name = db.Column(db.String(50), index=True)
phone = db.Column(db.String(24))
address = db.Column(db.String(255))
email = db.Column(db.String(255), unique=True, index=True, nullable=False,
server_default='')
password = db.Column(db.String(128), nullable=False, server_default='')
# Relations
company_id = db.Column(db.Integer, db.ForeignKey('companies.id',
onupdate='CASCADE',
ondelete='SET NULL'),
index=True)
views.py
app.route('/')
def index():
company = Company.query.get(1)
flash(company.name, company.user_count)
return render_template('index.html')
Error summary: "user_count" attribute is not part of the Company model.
I want to get the number of the users dynamically from Company model. Attribute should count users on each call of the model and serve it on a regular attribute (like company.user_count). I made it by creating a class method and calling it in view function but i want it to make the process automatic without calling method prior to use attribute.
I tried init function like this:
def __init__(self):
self.user_count = len(self.users)
And like this:
def __init__(self):
self.status()
def status(self):
self.user_count = len(self.users)
return True
And like this:
def __init__(self):
self.status()
#classmethod
def status(self):
self.user_count = len(self.users)
return True
all three versions throws same error. How can i overcome the problem.
Thanks a lot!
You can use a property:
class User(Base):
...
#property
def user_count(self):
return len(self.users)