First of all, most of all problems can be solved by separating functions into parts and checking if each part works as expected, so let's refactor your code a bit.
# 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)
now we can see that we save each purchase by user id, but it probably auto-incremented column or there are column for user id, not for purchase id, i don't know what your database schema is
If purchases table's id column is auto-incremented, we can remove user_id parameter
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)
If purchases table has both id and user_id columns and we want to insert record with user_id specified it should be like
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)
Hope it helps.
