python - flask_sqlalchemy操作mysql报错

使用flask_alchemy操作mysql数据库时候有报错，报错如下：C:UserslyonPCAppDataLocalProgramsPythonPython35libsite-packagessqlalchemyenginedefault.py:450: Warning: Incorrect string value: 'xD6xD0xB9xFAxB1xEA...' for column 'VARIABLE_VALUE' at row 478
cursor.execute(statement, parameters)

环境为WINDOWS10 X64位系统，sublime3 python3.5.1。

虽然有报错，但是数据已经添加到数据库中，可以在数据库中查看的到。请问此报错是指哪个字符串不正确？

代码如下：

#-*- coding:utf-8 -*-
from flask import Flask
from flask_sqlalchemy import SQLAlchemy

app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'mysql://root:lyoncc@localhost:3306/test'
app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = True
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, id,username, email):
        self.id = id
        self.username = username
        self.email = email

    def __repr__(self):
        return '' % self.username
db.create_all()
use = User(id= 4,username='3lyon31',email='hehe1@qq.com')
db.session.add(use)
db.session.commit()