无法在 Flask 网页上显示 WTForms _formhelpers显示错误消息

Question

如果这句话写得不好，我们深表歉意。当我没有满足验证要求时，似乎无法显示任何错误消息。当我提交时，表单只是被刷新而没有诸如"之类的错误消息；此字段是必需的"；。

此外，当我输入数据时，if form.validate_on_submit():不会返回预期的主页，它再次只是刷新页面。我知道表单没有任何作用，我计划将提交的数据添加到数据库中，但我一直坚持这一步。有人能帮忙吗？谢谢

应用程序

from cs50 import SQL
from flask import Flask, render_template, session, redirect
from flask_session import Session
from flask_wtf import FlaskForm
from wtforms import StringField, PasswordField, BooleanField #bool for checkbox
from wtforms.validators import InputRequired, Email, Length

# configure application
app = Flask(__name__)
app.config["SESSION_PERMENANT"] = False
app.config["SESSION_TYPE"] = "filesystem"
Session(app)
# Allows webpage to update html on refresh
app.config["TEMPLATES_AUTO_RELOAD"] = True
app.config['SECRET_KEY'] = 'Itsasecret'
# configure CS50 library to use SQLite database
db = SQL("sqlite:///project.db")
# Usually separate routes, database and form stuff into different files and link together
class LoginForm(FlaskForm):
username =  StringField('Username', validators=[InputRequired(), Length(min=4, max=15)])
password = PasswordField('Password', validators=[InputRequired(), Length(min=8, max=80)]) #80 is a special number (learn more)
remember = BooleanField('Remember me')
@app.route('/')
def homepage():
return render_template("homepage.html")
@app.route('/login', methods=['GET', 'POST'])
def login():
form = LoginForm()
if form.validate_on_submit():
return redirect("/")
return render_template("login.html", form=form)

登录模板

{% extends "layout.html" %}
{% from "_formhelpers.html" import render_field %}
{% set active_page = 'login' %}
{% block title %} Login {% endblock %}
{% block body %}
<div class="ls-main">
<form action="/login" method="POST">
{{ form.csrf_token }}        
{{ render_field(form.username) }}
{{ render_field(form.password, autocomplete="off") }}
{{ render_field(form.remember) }}
<div class="ls-div">
<input class="ls-input, signinbutton" name="submit" type="submit" value="Submit">
</div>
</form>
</div>
{% endblock %}

_formhelpers.html

{% macro render_field(field) %}
<dt>{{ field.label }}
<dd>{{ field(**kwargs)|safe }}
{% if field.errors %}
<ul class=errors>
{% for error in field.errors %}
<li>{{ error }}</li>
{% endfor %}
</ul>
{% endif %}
</dd>
{% endmacro %}

Answer 1

return render_template("/")无效。我想你是指return redirect("/")

当然你需要from flask import Flask, render_template, session, redirect