class Location(db.Model):
    location_id = db.Column(db.Integer, primary_key = True)
    location_country = db.Column(db.String)
    location_region = db.Column(db.String)
    location_state = db.Column(db.String)
    location_town = db.Column(db.String)
    nodes = db.relationship('Node', backref = 'location')

class Company(db.Model):
    company_id = db.Column(db.Integer, primary_key = True)
    company_name = db.Column(db.String, unique = True, nullable=False)
    contacts = db.relationship('Contact', backref = 'company')
    nodes = db.relationship('Node', backref = 'company', lazy = 'dynamic')

class Node(db.Model):
    node_id = db.Column(db.Integer, primary_key = True)
    node_name = db.Column(db.String, index = True, unique = True, nullable=False)
    location_id = db.Column(db.Integer, db.ForeignKey('location.location_id'))
    company_id = db.Column(db.Integer, db.ForeignKey('company.company_id'))


#Flask View
@app.route('/company/')
def companies():
    companies = models.Company.query.order_by(models.Company.company_name).all()
    return render_template('companies.html', companies=companies)