我完全不知道下面内容是怎么回事，求大家帮忙解答一下？

Question

我在使用python flask框架时， 在查询数据库数据：oPropertyService = db.session.query(PropertyServiceManager).filter_by(id=psid).first()调试后出现提示错误：unable to get repr for <class 'app.model.propertyServiceManager.PropertyServiceManager'>

Answer 1

python3下用flask-sqlalchemy对mysql数据库操作案例：
from flask import Flask
from flask.ext.sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://username:password@localhost/db_name'
db = SQLAlchemy(app)

class User(db.Model):
id = db.Column(db.Integer, primary_key=True)
username = db.Column(db.String(80), unique=True)
email = db.Column(db.String(120), unique=True)

def __init__(self, username, email):
self.username = username
self.email = email

def __repr__(self):
return '<User %r>' % self.username

admin = User('admin', '[e-mail]')

db.create_all() # In case user table doesn't exists already. Else remove it.

db.session.add(admin)

db.session.commit() # This is needed to write the changes to database

User.query.all()

User.query.filter_by(username='admin').first()