如何在flask-wtforms中显示来自InputRequired的消息

Question

在此脚本中，我将wtforms.validator中InputRequired的消息设置为显示错误。另外，我给出了一个字符长度的max和min。但这些论点并不起作用。

from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, IntegerField, SubmitField,StringField
from wtforms.validators import ValidationError, Length, EqualTo, InputRequired, Email

class Login(FlaskForm):
    email =StringField(validators=[InputRequired(message = 'please input something'), Length(min=10, max=20), Email(message='this is not email')])
    password = PasswordField(validators=[InputRequired(message='please input something'), Length(min=8, max=20, message='you must be input more than 8 character')])
    submit = SubmitField('Enter')

class Register(FlaskForm):
    email =StringField(validators=[InputRequired(message = 'please input something'), Length(min=10, max=20), Email(message='this is not email')])
    phone = IntegerField(validators=[InputRequired(message='please input something')])
    password = PasswordField(validators=[InputRequired(message='please input something'), Length(min=8, max=20, message='you must be input more than 8 character')])
    submit = SubmitField('Enter')

此脚本为login.html

{% extends "base.html" %}
{% block content %}
<h3>this is Home page</h3>
<form action="#">
    <!-- {{forlogin.hidden_tag()}} -->
    {{forlogin.email(placeholder="email")}}
    <br>
    {{forlogin.password(placeholder="password")}}
    <br>
    {{forlogin.submit}}
</form>
{% endblock content %}

Answer 1

从WTForms文档中的字段类文档：

错误

如果验证遇到任何错误，它们将被插入到此列表中。

因此，要显示错误，您必须在页面上显示列表中的项目：

   <form action="#">
        {{login.email(placeholder="email")}}{% for error in login.email.errors %} {{ error }} {% endfor%}
   </form>

我不知道双花括号之间的for是用来做什么的，我把它删除了。它导致了Jinja2中的错误。