AttributeError: 'scoped_session' object has no attribute 'session'

Question

I am trying to insert new data to my database but my web application returns this error.
My codes are as follows:

models.py

import os

from flask import Flask
from flask_sqlalchemy import SQLAlchemy

db = SQLAlchemy()

...

class Patient(db.Model):
    __tablename__ = "patients"
    id = db.Column(db.Integer, primary_key=True)
    lname = db.Column(db.String, nullable=False)
    fname = db.Column(db.String, nullable=False)
    mname = db.Column(db.String, nullable=True)
    address = db.Column(db.String, nullable=False)
    birthdate = db.Column(db.Date, nullable=False)
    date_modified = db.Column(db.DateTime, nullable=False)
    modified_by = db.Column(db.Integer, db.ForeignKey("users.id"), nullable=False)
    date_created = db.Column(db.DateTime, nullable=False)
    created_by = db.Column(db.Integer, db.ForeignKey("users.id"), nullable=False)

    def __init__(self, fname, mname, lname):
        self.fname = fname
        self.mname = mname
        self.lname = lname

application.py

import os

from flask import *
from flask_session import Session
from sqlalchemy import *
from sqlalchemy.orm import scoped_session, sessionmaker
from models import *

app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"] = os.getenv("DATABASE_URL")

# Check for environment variable
if not os.getenv("DATABASE_URL"):
    raise RuntimeError("DATABASE_URL is not set")

app.secret_key = '######'
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db.init_app(app)

engine = create_engine(os.getenv("DATABASE_URL"))
db = scoped_session(sessionmaker(bind=engine))

...

@app.route("/submitpatient",  methods=["POST"])
def submitpatient():
    fname = request.form.get("fname")
    mname = request.form.get("mname")
    lname = request.form.get("lname")

    patient = Patient(fname=fname, mname=mname, lname=lname)

    db.session.add(patient)
    db.session.commit()

    return redirect(url_for('index'))

I’m new to python and I have been trying to find the error in my code for hours but I can’t seem to find anything that would help me.

Asked By: pi3.14

||

Source

Answer 1

I guess the problem that u missed to create a constructor “Session” after using it,
The code will be:

# create a configured "Session" class
Session = scoped_session(sessionmaker(bind=engine))
@app.route("/submitpatient",  methods=["POST"])
def submitpatient():
    fname = request.form.get("fname")
    mname = request.form.get("mname")
    lname = request.form.get("lname")

    patient = Patient(fname=fname, mname=mname, lname=lname)
    #create a Session
    session = Session()

    session.add(patient)
    session.commit()

    return redirect(url_for('index'))

for more information, see this

Answered By: Mahrez BenHamad

Answer 2

What if you just add and commit as follows,

db.add(patient)
db.commit()

Answered By: rosefun

Answer 3

Use Session object with SQLAlchemy’s declarative way

I know this answer is not exactly related to the questioner’s scenario but a similar issue can arise if you are using flask-security‘s user model with sqlalchemy in a declarative way.

In this case, your user_datastore should be as below:

user_datastore = SQLAlchemySessionUserDatastore(db_session, User, Role) not SQLAlchemyUserDatastore

For more explanation:

database.py

import importlib
from sqlalchemy import create_engine
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy.ext.declarative import declarative_base

engine = create_engine("sqlite:///crm.sqlite3")
db_session = scoped_session(sessionmaker(autocommit=False,
                                         autoflush=False,
                                         bind=engine))
Base = declarative_base()
Base.query = db_session.query_property()

def create_db(all_microservices_names = []):
    _ = importlib.import_module("database.models.all_models")
    Base.metadata.create_all(bind=engine)

all_models.py

import sqlalchemy as sa
from database.database import Base
from flask_security import RoleMixin, UserMixin

class User(Base, UserMixin):
    id = sa.Column(sa.Integer(), primary_key=True)
    public_id = sa.Column(sa.String(length=255), unique=True, nullable=False)
    username = sa.Column(sa.String(20), unique=True, nullable=False)
    #...

datastore.py

from flask_security import SQLAlchemySessionUserDatastore
from database.database import db_session
from database.models.user_models import User, Role

user_datastore = SQLAlchemySessionUserDatastore(db_session, User, Role)

app.py will contain the initialization of these elements including login_manager and attach it to the Flask app.

Answered By: Karishma Sukhwani

AttributeError: 'scoped_session' object has no attribute 'session'

Question:

Answers:

Use Session object with SQLAlchemy’s declarative way