我无法将表单答案附加到 Python 中的列表答案

【问题标题】：I can't append a form answer to a list in Python我无法将表单答案附加到 Python 中的列表
【发布时间】：2022-06-28 21:45:07
【问题描述】：

我正在使用 Flask 开发一个聊天网络应用程序。我在想我会通过将用户消息附加到列表来显示它们，但由于某种原因它不起作用。表单请求似乎有问题，因为当我打印它时它没有显示任何内容。添加占位符消息有效，所以我知道问题出在我附加的部分。这是 Python 代码：


from cs50 import SQL
from flask import Flask, flash, redirect, render_template, request, session
from flask_session import Session
from tempfile import mkdtemp
from werkzeug.security import check_password_hash, generate_password_hash
from datetime import datetime

from helpers import apology, login_required

# Configure application
app = Flask(__name__)

# Ensure templates are auto-reloaded
app.config["TEMPLATES_AUTO_RELOAD"] = True

# Configure session to use filesystem (instead of signed cookies)
app.config["SESSION_PERMANENT"] = False
app.config["SESSION_TYPE"] = "filesystem"
Session(app)

@app.after_request
def after_request(response):
    """Ensure responses aren't cached"""
    response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
    response.headers["Expires"] = 0
    response.headers["Pragma"] = "no-cache"
    return response

@app.route("/")
def index():
    """Chat with other people."""
    messages = []
    if request.method == "POST":
        message = request.form.get("message")
        messages.append(message)
    else:
        return render_template("chat.html", messages=messages)

HTML 代码：

<!DOCTYPE html>

<html lang="en">
    <head>
        <meta charset="utf-8">
        <meta name="viewport" content="initial-scale=1, width=device-width">

         <!-- http://getbootstrap.com/docs/5.1/ -->
        <link crossorigin="anonymous" href="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/css/bootstrap.min.css" integrity="sha384-1BmE4kWBq78iYhFldvKuhfTAU6auU8tT94WrHftjDbrCEXSU1oBoqyl2QvZ6jIW3" rel="stylesheet">
        <script crossorigin="anonymous" src="https://cdn.jsdelivr.net/npm/bootstrap@5.1.3/dist/js/bootstrap.bundle.min.js" integrity="sha384-ka7Sk0Gln4gmtz2MlQnikT1wXgYsOg+OMhuP+IlRH9sENBO0LRn5q+8nbTov4+1p"></script>

        <link href="/static/styles.css" rel="stylesheet">
    </head>
    <body>
        <form method="post" class="position-absolute bottom-0 start-50 translate-middle-x">
            <input type="text" id="chat" name="message" id="message" autocomplete="off" class="textbox">
            <button class="btn btn-primary" type="submit" id="chat" class="send">send</button>
        </form>
        <div class="overflow-auto">
            {% for message in messages %}
                {{ message }}
            {% endfor %}
        </div>
    </body>
</html>

【问题讨论】：

标签： python forms flask web chat

【解决方案1】：

您的index 函数在每次调用时都会创建空的messages 列表。尝试将messages 移动到Session(app) 之后的外部范围

【讨论】：