Flask-SQLAlchemy Query Join relational tables

Question

I am building an app using Flask & SQLAlchemy. I basically have 3 tables: users, friendships and bestFriends:

A user can have many friends but only one best frie

Answer 1

Ok looks like after getting some sleep and viewing Matthewh's suggestion I almost found the final solution:

My model:

from app import db
from sqlalchemy.orm import relationship, backref
from sqlalchemy import Table, Column, Integer, ForeignKey
from sqlalchemy.ext.declarative import declarative_base

class users(db.Model):
    __tablename__ = "Users"

    id = db.Column(db.Integer, primary_key=True)
    userName = db.Column(db.String, nullable=False)
    userEmail = db.Column(db.String, nullable=False)
    userPhone = db.Column(db.String, nullable=False)
    userPass = db.Column(db.String, nullable=False)

    def __init__(self, userName, userEmail, userPhone, userPass):
        self.userName = userName
        self.userEmail = userEmail
        self.userPhone = userPhone
        self.userPass = userPass

    def __repr__(self):
        return '{}-{}-{}-{}'.format(self.id, self.userName, self.userEmail, self.userPhone)


 class friendships(db.Model):
    __tablename__ = "Friendships"

    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('Users.id'), nullable=False)
    friend_id = db.Column(db.Integer, db.ForeignKey('Users.id'), nullable=False)
    userR = db.relationship('users', foreign_keys='friendships.user_id')
    friendR = db.relationship('users', foreign_keys='friendships.friend_id')

    def __init__(self, user_id, friend_id):
        self.user_id = user_id
        self.friend_id = friend_id

    def __repr__(self):
        return '{}-{}-{}-{}'.format(self.user_id, self.friend_id)


class bestFriends(db.Model):
    __tablename__ = "BestFriends"

    id = db.Column(db.Integer, primary_key=True)
    user_id = db.Column(db.Integer, db.ForeignKey('Users.id'), nullable=False)
    best_friend_id = db.Column(db.Integer, db.ForeignKey('Users.id'), nullable=False)
    user = db.relationship('users', foreign_keys='bestFriends.user_id')
    best_friend = db.relationship('users', foreign_keys='bestFriends.best_friend_id')

    def __init__(self, user_id, best_friend_id):
        self.user_id = user_id
        self.best_friend_id = best_friend_id

    def __repr__(self):
        return '{}-{}-{}-{}'.format(self.user_id, self.best_friend_id)

My app.py function(shows friends of user logged in):

@app.route('/friendList', methods=['GET', 'POST'])
@app.route('/friends')
  def friendList(page=1):
  if not session.get('logged_in'):
     return render_template('login.html')
  else:
     userID = session['user_id']
     userList = users.query.join(friendships, users.id==friendships.user_id).add_columns(users.id, users.userName, users.userEmail, friendships.id, friendships.user_id, friendships.friend_id).filter(friendships.friend_id == userID).paginate(page, 1, False)
     return render_template('friends.html', userList=userList)

And the Jinja side of 'friends.html':

{% extends "layout.html" %}

{% block body %}
    

        {% if userList.has_prev %}
            Back
        {% endif %}

        {% if userList.has_next %}
            Next
        {% endif %}
    

    


    

    {% if userList.items %}
        {% for friends in userList.items %}
            

                {{ friends.userName }}
            
            




        {% endfor %}
        {% else %}
            
No friends
        {% endif %}
    
{% endblock %}

This gives me an object(friends in userList.items) like this:

(2-Carlos-carlos@carlos.com-900102030, 2, u'Carlos', u'carlos@carlos.com', 2, 2, 1)

I was expecting this: |users.id|users.userName|users.userEmail|users.userPhone|friendships.id|friendships.user_id(the friends)| friendships.friend_id(the logged in user)|

So I have the following doubts/questions:

I am not completely understanding the structure of the object resulting for the query:

-repeated user id, name and email -what is the 'u' infront of second name and email

I am not completely understanding the relations model structure:

• why is the following NOT required in the 'users' class of the database model:

  #friendsR = db.relationship('friendships', backref='friendships.friend_id', primaryjoin='users.id==friendships.user_id', lazy='joined')
  

IS my database model correctly defined regarding standarized relationship model as posted in this answer or should I improove some how??