之前设置的请求cookies在Flask应用程序中返回None

from flask import Flask, make_response

app = Flask(__name__)

@app.route('/')
def index():
    resp = make_response('Hello, World!')
    resp.set_cookie('cookie_name', 'cookie_value', expires=3600)
    return resp

from flask import Flask, request

app = Flask(__name__)

@app.route('/')
def index():
    cookie_value = request.cookies.get('cookie_name')
    return f'Cookie value: {cookie_value}'

from flask import Flask, make_response

app = Flask(__name__)

@app.route('/')
def index():
    resp = make_response('Hello, World!')
    resp.delete_cookie('cookie_name')
    return resp