首先，大多数问题都可以通过将函数分成几部分并检查每个部分是否按预期工作来解决，所以让我们稍微重构一下代码。
# additional import for generating URL from parts,
# not by concatenating strings
import urllib.parse
@app.route("/buy", methods=["GET", "POST"])
@login_required
def buy():
if request.method != "POST":
return render_template("buy.html")
# http://stackoverflow.com/questions/32640090/python-flask-keeping-track-of-user-sessions-how-to-get-session-cookie-id
user_id = session.get('user_id')
# what is "full_url"?
# to which resource and what we get with it?
full_url = generate_url(symbol=request.form["symbol"])
# http://stackoverflow.com/questions/21351882/reading-data-from-a-csv-file-online-in-python-3
response = urllib.request.urlopen(full_url)
datareader = csv.reader(io.TextIOWrapper(response))
quote_list = list(datareader)
num_shares = request.form["num_shares"]
# what first element means,
# if it contains info about specific data
# there should be name for it
quote_list_first_element = quote_list[0]
name = quote_list_first_element[0]
# is this symbol different from one in "request.form"?
symbol = quote_list_first_element[1]
price = float(quote_list_first_element[2])
# http://stackoverflow.com/questions/12078571/jinja-templates-format-a-float-as-comma-separated-currency
total_cost = get_total_cost(price, num_shares)
username = fetch_user_name(user_id)
save_purchase(user_id=user_id,
symbol=symbol,
name=name,
price=price,
num_shares=num_shares,
total_cost=total_cost)
return render_template("bought.html",
username=username,
id=user_id,
name=name,
symbol=symbol,
price=price,
num_shares=num_shares,
total_cost=total_cost)
def fetch_user_name(user_id):
username = db.execute("SELECT username FROM users WHERE id = :user_id",
user_id=user_id)
username = username[0]
username = username.get('username')
return username
def save_purchase(user_id, name, num_shares,
price, symbol, total_cost):
db.execute(
"INSERT INTO purchases (id, symbol, name, num_shares, price, total) "
"VALUES (:user_id, :symbol, :name, :num_shares, :price, :total)",
# FIXME: if "purchases" table's "id" column is a primary key
# here we are saving purchase by user id
# not by purchase id (which probably is auto-incremented
# and should not be specified in insert query at all),
# so for each user we will have only one purchase since primary key is unique
user_id=user_id,
symbol=symbol,
name=name,
price=price,
# maybe it will be better to rename column into "num_shares"?
shares=num_shares,
# maybe it will be better to rename column into "total_cost"?
total=total_cost)
def get_total_cost(price, num_shares):
return round((float(price) * 100.0) * float(num_shares) / 100.0, 2)
def generate_url(symbol):
scheme = 'http'
netloc = 'download.finance.yahoo.com'
path = '/d/quotes.csv'
params = ''
# what 's' query parameter means?
# looks like it stands for "symbol", but which one?
# is it product label or something else?
query_dict = dict(s=symbol,
f='nsl1d1t1c1ohgv',
e='.csv')
query_str = urllib.parse.urlencode(query_dict)
fragment = ''
components = [scheme, netloc, path, params, query_str, fragment]
return urllib.parse.urlunparse(components)
现在我们可以看到我们通过用户 ID 保存每次购买，但它可能是自动递增的列或者有用户 ID 列，而不是购买 ID，我不知道你的数据库架构是什么
如果purchases表的id列是自增的，我们可以去掉user_id参数
def save_purchase(name, num_shares,
price, symbol, total_cost):
db.execute(
"INSERT INTO purchases (symbol, name, num_shares, price, total) "
"VALUES (:symbol, :name, :num_shares, :price, :total)",
symbol=symbol,
name=name,
price=price,
shares=num_shares,
total=total_cost)
如果purchases 表同时具有id 和user_id 列，我们要插入指定user_id 的记录，它应该是这样的
def save_purchase(user_id, name, num_shares,
price, symbol, total_cost):
db.execute(
"INSERT INTO purchases (user_id, symbol, name, num_shares, price, total) "
"VALUES (:user_id, :symbol, :name, :num_shares, :price, :total)",
user_id=user_id,
symbol=symbol,
name=name,
price=price,
shares=num_shares,
total=total_cost)
希望对你有帮助。