some beginners confusion with flask-sqlalchemy - python-3.x

Question

sqlalchemy and I'm trying to understand the finer workings of the way the objects work. I've got some test code that just seems to work differently than the tutorials and I am getting confused. I think this is a case of the tensorflow 1 vs 2 docs confusion happening
the code I posted, I'm told works for other people, and the last line of that is database.session.commit(), the code is the last code block.
This is a brand new Debian Stable VM with only VSCode, terminator and bpython installed beyond what is necessary for the application. THIS SHOULD WORK.
the database file is created but not populated. the tables are created but not columns or rows.
sqlite3 shell shows that nothing is in the database but the tables are there
database.session.flush()
does not add the stuff either
database.session.query(User).all()
also returns an empty thingamabob
and
database.session.query(User).filter(User.user_id)
returns : SQLAlchemy object has no attribute "query"
I'm trying to make a function that returns the user object based on its user_id and then change a variable in that user object using
object.field = "blorp"
I can make an object and access it like
user = User()
user.user_id
but for some strange reason, even though I have defaults set, it doesn't have those fields populated with those defaults. I have to explicitly define the fields during the declaration
but I can assign stuff like:
user.user_id = 2
this object returns ALL of the users right?
>>> asdf = database.session.query(User)
>>> asdf
<flask_sqlalchemy.BaseQuery object at 0x7f49aacff780>
the "all()" method returns an empty array for both class.query and database.session.query
>>> users = User.query.all()
>>> users
[]
>>> users = database.session.query(User).all()
>>> users
[]
Using the following test code:
from flask.config import Config
from flask import Flask, render_template, Response, Request ,Config
from flask_sqlalchemy import SQLAlchemy
HTTP_HOST = "gamebiscuits"
ADMIN_NAME = "Emperor of Sol"
ADMIN_PASSWORD = "password"
ADMIN_EMAIL = "game_admin"
DANGER_STRING= "TACOCAT"
class Config(object):
SQLALCHEMY_DATABASE_URI = 'sqlite:///' + HTTP_HOST + '.db'
SQLALCHEMY_TRACK_MODIFICATIONS = True
solar_empire_server = Flask(__name__ , template_folder="templates" )
solar_empire_server.config.from_object(Config)
database = SQLAlchemy(solar_empire_server)
def update_database(thing):
database.session.add(thing)
database.commit()
def user_by_id(id_of_user):
return User.query.filter_by(user_id = id_of_user).first()
#without the flask migrate module, you need to instantiate
# databases with default values. That module wont be loaded
# yet during the creation of a NEW game
class User(database.Model):
user_id = database.Column(database.Integer, default = 0, primary_key = True)
username = database.Column(database.String(64), default = "tourist", index=True, unique=True)
email = database.Column(database.String(120), default = DANGER_STRING , index=True, unique=True)
password_hash = database.Column(database.String(128), default = DANGER_STRING)
turns_run = database.Column(database.Integer, default = 0)
cash = database.Column(database.Integer, default = 1000)
def __repr__(self):
return '<User id:{} name: {} >'.format(self.user_id , self.username)
class UserShip(User):
ship_id = database.Column(database.String(128), default = "1")
ship_name = database.Column(database.String(128), default = "goodship moop")
def __repr__(self):
return '<User id:{} name: {} >'.format(self.ship_id , self.ship_name)
admin = User(username=ADMIN_NAME, user_id = 1, email=ADMIN_EMAIL , password_hash = ADMIN_PASSWORD)
guest = User(username='guest', user_id = 2, email='test#game.net' , password_hash = 'password')
user = User()
usership = UserShip()
adminship = UserShip()
guestship = UserShip()
database.create_all()
database.session.add(admin)
database.session.add(guest)
database.session.add(user)
database.session.add(usership)
database.session.add(adminship)
database.session.add(guestship)
database.session.commit()

Answer 1

Okay, so when you see default here it's going to be on INSERT (see the SQLAlchemy default documentation).
To quote the key part here:
Column INSERT and UPDATE defaults refer to functions that create a default value for a particular column in a row as an INSERT or UPDATE statement is proceeding against that row, in the case where no value was provided to the INSERT or UPDATE statement for that column.
So these defaults will only be initialized on adding to the database, flushing won't have any effect if an object that hasn't been added (session.add). So User() is only going to create an object, it will not create a DB row until you add (and flush / commit as necessary).