Python Flask 解决form.validate_on_submit()总是为false的问题

# 表单类：
class Form(FlaskForm):
    username = StringField("用户名：", validators=[DataRequired()])
    phone = IntegerField("手机号：", validators=[DataRequired()])
    email = StringField("邮箱：", validators=[DataRequired(),email("Email ERROR")])
    age = IntegerField("年龄：", validators=[DataRequired()])
    about = TextAreaField("关于我：", validators=[DataRequired()])
    submit = SubmitField("注册")
    password = PasswordField("密码：", validators=[DataRequired()])
    confirm = PasswordField("确定密码：", validators=[DataRequired()])

# 视图函数：
@app.route("/",methods=["GET","POST"])
def index():
    form=Form()
    print(form.validate_on_submit())
    if form.validate_on_submit():
        return redirect(url_for("suc"))
    else:
        return render_template("register2.html",form=form)

@app.route("/suc")
def suc():
    return "SUCCESS"

 HTML代码：

    

        {{ form.username.label }} 
 {{ form.username(class="form-control",placeholder="请输入用户名") }} 

    
    

        {{ form.password.label }} 
 {{ form.password(class="form-control",placeholder="输入密码") }} 

    
    

        {{ form.confirm.label }} 
 {{ form.confirm(class="form-control",placeholder="确认密码") }} 

    
    

        {{ form.phone.label }} 
 {{ form.phone(class="form-control",placeholder="输入手机号") }} 

    
    

        {{ form.email.label }} 
 {{ form.email(class="form-control",placeholder="输入邮箱") }} 

    
    {% for msg in form.email.errors %}
    {{ msg }}
    {% endfor %}
    

        {{ form.age.label }} 
 {{ form.age(class="form-control",placeholder="输入年龄") }} 

    
    

        {{ form.about.label }} 
 {{ form.about(class="form-control",placeholder="输入我的简介") }} 

    
    

        {{ form.submit(class="btn btn-default") }}
    

我只用email一项进行测试。

这样呢form.validate_on_submit()返回的都是false，将表单类中含有中文字符串改成unicode字符解决中文编码问题

# 表单类：
class Form(FlaskForm):
    username = StringField(u"用户名：", validators=[DataRequired()])
    phone = IntegerField(u"手机号：", validators=[DataRequired()])
    email = StringField(u"邮箱：", validators=[DataRequired(),email("Email ERROR")])
    age = IntegerField(u"年龄：", validators=[DataRequired()])
    about = TextAreaField(u"关于我：", validators=[DataRequired()])
    submit = SubmitField(u"注册")
    password = PasswordField(u"密码：", validators=[DataRequired()])
    confirm = PasswordField(u"确定密码：", validators=[DataRequired()])

然后再把HTML代码中form标签里面加入{{ form.hidden_tag() }}，这样form.validate_on_submit()才能起作用（我也不知道为啥要加。。）