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How to call an attribute inside the model in FLASK SQLAlchemy

I'm trying to call an attribute inside a model in SQLAlchemy this way
app = Flask(__name__)
app.config.from_object('config')
db = SQLAlchemy(app)
class Show(db.Model):
__tablename__ = 'Show'
id = db.Column(db.Integer, primary_key=True)
venue_id = db.Column(
db.Integer, db.ForeignKey('Venue.id'), nullable=True)
class Venue(db.Model):
__tablename__ = 'Venue'
id = db.Column(db.Integer, primary_key=True)
upcoming_shows = Show.query.filter(Show.venue_id == 1).filter(
Show.start_time >= func.current_date()).all()
I want to replace 1 here with the id of the current Venue.. I tried the following:
self.id: returns "Undefined variable: 'self'"
id: returns "Cannot compile Column object until its 'name' is
assigned"
Thanks for help

The simplest solution is to use a hybrid property. A hybrid property is accessible like a normal attribute, but it can run queries to retrieve its value.
from sqlalchemy.ext.hybrid import hybrid_property
class Venue(db.Model):
id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(50))
#hybrid_property
def upcoming_shows(self):
upcoming_shows = Show.query.filter(Show.venue_id == self.id).filter(
Show.start_time >= db.func.current_date()).all()
return upcoming_shows
#app.route("/", methods=["GET"])
def index():
venue = Venue.query.first()
shows = venue.upcoming_shows
...

Instance <User at xxxx> is not bound to a Session; attribute refresh operation cannot proceed

I first request is right, But when I second request is wrong. I know the reason get this result is session object expired. But I don't know why? The flowing is my test script.
Detail:
In my actual project, I set a global variable current_user to save the current user, and then add some cache-related attributes to this global variable. The cache-related attributes are actually an object, which is called in the method of the object Pass in the ginseng.
import datetime
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from sqlalchemy import Integer, Column, DateTime, Integer, String, func, VARCHAR
app = Flask(__name__)
app.config[
"SQLALCHEMY_DATABASE_URI"
] = "mysql+mysqlconnector://root:123456#127.0.0.1:3306/pool"
# app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
db = SQLAlchemy(app)
# In my project I set global var to solve memory leak
current_user = {}
def get_cache(user):
def inner():
class hello:
def get_user_name(self):
# if user not in db.session:
# print("user 已经过期了")
# session_user = db.session.merge(user)
# else:
# session_user = user
# return "%s" % (session_user.username)
return "%s" % (user.username)
return hello()
return inner()
def get_current_user(ticker):
user = current_user.get(ticker)
if user:
return user
user = User.query.first()
current_user[ticker] = user
user.cache = get_cache(user)
return user
class User(db.Model):
__tablename__ = "user"
id = Column(Integer, primary_key=True)
username = Column(String(50), nullable=False, unique=True)
mobile = Column(String(20), nullable=False, unique=True)
password = Column(String(100), nullable=False)
is_admin = Column(Integer, default=0)
created_at = Column(DateTime, nullable=False, default=datetime.datetime.utcnow)
updated_at = Column(DateTime, nullable=False, default=datetime.datetime.utcnow)
level = Column(Integer, default=1)
remark = Column(String(100), nullable=False)
#app.after_request
def after_request(response):
db.session.rollback()
db.session.remove()
return response
#app.route("/test", methods=["GET"])
def test():
user = get_current_user("ltc")
print(user.username, "这个")
print(user.cache.get_user_name())
return "hello world"
if __name__ == "__main__":
app.run(host="127.0.0.1", port=5000)
My environment:
Flask==1.0.2
Flask-SQLAlchemy==2.3.2

How to get parrent of object in session SQLAlchemy

I have two tables:
class Project(DataBase):
__tablename__ = 'projects'
id = Column(Integer, primary_key=True, autoincrement=True, nullable=False)
name = Column(String, nullable=False, unique=True)
domain = Column(String, nullable=False)
phrases = relationship("Phrase", backref='proj')
def __init__(self, name, domain):
self.name = name
self.domain = domain
class Phrase(DataBase):
__tablename__ = 'phrases'
query_id = Column(Integer, primary_key=True, autoincrement=True, nullable=False)
query_text = Column(String, nullable=False)
project = Column(Integer, ForeignKey('projects.id'), nullable=False)
enable = Column(Boolean, nullable=False, default=True)
def __init__(self, query_text, project, city):
self.query_text = query_text
self.project = project
And I have a function:
def get_first_query():
session = Session(bind=engine)
q = session.query(Phrase).filter(Phrase.enable == True).first()
session.close()
return q
I want to get an object from table 2 and than get its parrent from first table:
session = Session(bind=engine)
q = get_first_query()
print(q.proj)
It doesn't work and print this error:
sqlalchemy.orm.exc.DetachedInstanceError: Parent instance is not bound to a Session; lazy load operation of
attribute 'proj' cannot proceed
I can do this:
session = Session(bind=engine)
q = get_first_query()
q_project = session.query(Project).filter(Project.id == q.project)
But it's a bad way.

You can assess related object via proj attribute.
session.query(Phrase).filter(
Phrase.enable == True
).first().proj
This way you'll hit database one additional time to get it so you'll need to open session again. To avoid additional queries you can use joined load:
session.query(Phrase).filter(
Phrase.enable == True
).options(
joinedload('proj')
).first().proj

How to query with many tables

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
#import sqlite3 as sql
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://ahmad:ahmad#192.168.3.103/utama'
db = SQLAlchemy(app)
class ak(db.Model):
__tablename__ = 'ak'
id = db.Column(db.Integer, primary_key=True)
nama = db.Column(db.String)
alamat = db.Column(db.String)
akreditasi = db.Column(db.String)
def __init__(self, id, nama, alamat, akreditasi):
self.id = id
self.city = nama
self.alamat = alamat
self.akreditasi = akreditasi
class av(db.Model):
__tablename__ = 'av'
id = db.Column(db.Integer, primary_key=True)
nama = db.Column(db.String)
alamat = db.Column(db.String)
akreditasi = db.Column(db.String)
def __init__(self, id, nama, alamat, akreditasi):
self.id = id
self.city = nama
self.alamat = alamat
self.akreditasi = akreditasi
id_jurusan = db.Table('id_jurusan',
db.Column('id', db.Integer, db.ForeignKey('ak.id')),
db.Column('id', db.Integer, db.ForeignKey('av.id'))
)
#app.route('/ak')
def jurusan(jurusan):
return render_template('index.html', rows=ak.query.all() )
#app.route('/av')
def Akuntansi():
return render_template('index.html', rows=av.query.all() )
if __name__ == '__main__':
app.run(debug=True, host='1.1.1.1', port=80)
I am a new to learn python, in this case I studied the framework flask and I had trouble on the declaration SQLAlchemy, precisely displays the contents of the table but with the same structure,when executed will be like this.....
[
which one success

You are using the decorator
#app.route('/av')
The method which succeeds Akuntansi() does not require a parameter. So this works. The method which fails expects a parameter jurusan(jurusan) but your decorator #app.route('/ak') does not consider this.
To pass a parameter you need to use the decorator like this:
#app.route("/ak/<jurusan>") and then also pass the parameter in the request.

SQLAlchemy Query foreignkey field(s)

I am trying to write a view/SQLAlchemy query that will allow me to display data thats linked as a ForeignKey and also where I have a ManyToMany relationship
have the models..
#Samples
class Sample(Base):
__tablename__ = 'samples'
id = Column(Integer, primary_key=True)
name = Column(Unicode)
def __unicode__(self):
return self.name
samples_to_customer = Table('samples_to_customer', Base.metadata,
Column('customer_id', Integer, ForeignKey('customer.id')),
Column('sample_id', Integer, ForeignKey('samples.id'))
)
#Create a cusotmer model to store customer numbers
class Customer(Base):
__tablename__ = 'customer'
id = Column(Integer, primary_key=True)
name = Column(Unicode, unique=True) #this will be the variable used to search the existing db
customer_samples = relationship('Sample', secondary='samples_to_customer', backref='samples')
sales_rep = Column(Integer, ForeignKey('rep.id'))
Rep = relationship('Rep')
def __unicode__(self):
return self.name
# This model will have its own entry view/page a user logs on and enters notes (according to a customer
# number) they then get stored/saved onto the Customers account
class Note(Base):
__tablename__ = 'note'
id = Column(Integer, primary_key=True)
name = Column(Unicode)
pub_date = Column(Date)
customer_no = Column(Integer, ForeignKey('customer.id'))
customer = relationship('Customer')
def __unicode__(self):
return self.name
And the views..
#view_config(route_name='view_customer', renderer='templates/view_customer.jinja2')
def view_page(request):
customer_no = request.matchdict['customer']
cust_slcustm = DBSessionRO.query(Slcustm).filter(Slcustm.customer == customer_no).first()
cust_customer = DBSessionRO.query(Custom).filter(Custom.cu_custref== customer_no).first()
# Return a 404 if a result isn't found, slcustm and customer share one2one relationship on customer_no
if cust_slcustm is None:
return HTTPNotFound('No such customer')
return dict(cust_slcustm=cust_slcustm, cust_customer=cust_customer)
But I cant seem to write a query that will display every sample and note related to a customer number? If anyone could help I would be very grateful :)

Try this
class Note(Base):
__tablename__ = 'note'
id = Column(Integer, primary_key=True)
name = Column(Unicode)
pub_date = Column(Date)
customer_no = Column(Integer, ForeignKey('customer.id'))
customer = relationship('Customer', backref='notes')
#view_config(route_name='view_customer', renderer='templates/view_customer.jinja2')
def view_page(request):
customer_no = request.matchdict['customer']
cust = DBSessionRO.query(Customer).filter(Customer.id == customer_no).first()
print "Sample :", cust.customer_sample
print "Notes :", cust.notes

What ended up working was:
#views.py
#view_config(route_name='view_customer', renderer='templates/view_customer.jinja2')
def view_page(request):
customer_no = request.matchdict['customer']
cust_slcustm = DBSessionRO.query(Slcustm).filter(Slcustm.customer == customer_no).first()
cust_customer = DBSessionRO.query(Custom).filter(Custom.cu_custref== customer_no).first()
cust_books = DBSessionRW.query(Customer).filter(Customer.name == customer_no).first()
# Return a 404 if a result isn't found, slcustm and customer share one2one relationship on customer_no
if cust_slcustm is None:
return HTTPNotFound('No such customer')
return dict(cust_slcustm=cust_slcustm, cust_customer=cust_customer, cust_books=cust_books)
Then creating the template:
{% for sample in cust_books.customer_samples %}
{{ sample.name }}
{% endfor %}