为什么显示--raise FieldNotRetrieved（self._name）mongoalchemy.exceptions.FieldNotRetrieved：name。错误

Question

我是pyhton-Flask的新手，我想创建一个登录应用程序。我在登录应用程序中使用Flask和PyMongo和mongoalchemy。运行程序时，代码显示以下错误。 >

Traceback (most recent call last):
    raise FieldNotRetrieved(self._name) mongoalchemy.exceptions.FieldNotRetrieved: name

代码：

from flask_mongoalchemy import MongoAlchemy
from flask_wtf import FlaskForm
from wtforms import TextField,BooleanField,StringField,PasswordField,validators
from wtforms.validators import InputRequired
app = Flask(__name__)
app.config['SECRET_KEY']='thisissecretkey'
app.config['MONGOALCHEMY_DATABASE'] = 'test'
app.config["MONGO_URI"] = "mongodb://localhost:27017/test"

db = MongoAlchemy(app)

class Author(db.Document):
    name = db.StringField()
    password = db.StringField()



class Reg(FlaskForm):
    name=StringField("name",validators=[InputRequired()])
    password=PasswordField("password",validators=[InputRequired()])

@app.route("/index",methods=['GET','POST'])
def hello():
    form = Reg()
    if request.method=='POST':
        if form.validate():
            Author(form.name.data,form.password.data).save()
            return "user is created"
        return "user is not created"
    return render_template('check.html',form=form)


if __name__=='__main__':
    app.run(debug=True)