Flask : TypeError:在使用Flask-WTF进行验证时，“str”对象不可调用

from flask import Flask, render_template
from flask_wtf import FlaskForm
from wtforms import StringField, SubmitField
from wtforms.validators import DataRequired

app = Flask(__name__)
app.config['SECRET_KEY'] = 'your-secret-key'

class MyForm(FlaskForm):
    name = StringField('Name', validators=[DataRequired()])
    submit = SubmitField('Submit')

@app.route('/', methods=['GET', 'POST'])
def index():
    form = MyForm()
    if form.validate_on_submit():
        name = form.name.data
        # 处理表单数据
        return f'Hello, {name}!'
    return render_template('index.html', form=form)

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