Error while trying to display data using sqlite3 and flask - python-3.x

Question

I am trying to display a portfolio of stocks. The task is to access the database and then to lookup for the current price of the stock, displaying it, the total value of the stocks, the remaining cash from 10000 and the grand total, that should be changing depending on the current stock price.
I have tried various ways to access and display data but I am constantly having errors and I need a help, please. I have also tried to create a for loop and to append data to list but again without success.
The error is:
File "/home/ubuntu/finance/application.py", line 58, in index
current_price=lookup(row["symbol"]["price"])
TypeError: 'NoneType' object is not subscriptable
My code is below:
#app.route("/")
#login_required
def index():
"""Show portfolio of stocks"""
#Access the stocks of the current user from DB
rows=db.execute("SELECT symbol, name, sum(shares) as shares FROM stocks WHERE user_id=:user_id ORDER BY symbol", user_id=session["user_id"])
#Check the current price of each stock using the helper function lookup and calculate the total cost of each stock( * number of shares by price)
#add that info to rows and render it on the index page
sum_total_cost=0
for row in rows:
#symbol=row["symbol"]
#current_price=lookup(symbol["price"])
current_price=lookup(row["symbol"]["price"])
total_cost=current_price*(row["shares"])
row["current_price"]=usd(current_price)
row["total_cost"]=usd(total_cost)
sum_total_cost+=total_cost
#Check the current cash of the user
user_id=session["user_id"]
user = db.execute("SELECT cash FROM users WHERE id=:user_id", user_id=user_id)
cash=user[0]["cash"]
grand_total = cash+sum_total_cost
return render_template("index.html", rows=rows, cash = cash, grand_total=grand_total)
And HTML
{% extends "layout.html" %}
{% block title %}
Index
{% endblock %}
{% block main %}
<h2>Portfolio</h2>
<table class="table table-striped">
<thead>
<tr>
<th>Symbol</th>
<th>Name</th>
<th>Shares</th>
<th>Price</th>
<th>Total Cost</th>
</tr>
</thead>
<tbody>
<!-- TODO: Loop through the database to display all transactions and the balance -->
{% for row in rows %}
<tr>
<td>{{row.symbol}}
<td>{{row.name}}</td>
<td>{{row.shares}}</td>
<td>{{row.current_price}}</td>
<td>{{row.total_cost}}</td>
{% endfor %}
</tr>
<tr>
<th>Cash</th>
<td></td>
<td></td>
<td></td>
<td>{{cash}}</td>
</tr>
<tr>
<th>Grand Total</th>
<td></td>
<td></td>
<td></td>
<td>{{grand_total}}</td>
</tr>
</tbody>
</table>
</div>
</div>
{% endblock %}
Lookup function
def lookup(symbol):
"""Look up quote for symbol."""
# Contact API
try:
api_key = os.environ.get("API_KEY")
url = f"https://cloud-sse.iexapis.com/stable/stock/{urllib.parse.quote_plus(symbol)}/quote?token={api_key}"
response = requests.get(url)
response.raise_for_status()
except requests.RequestException:
return None
# Parse response
try:
quote = response.json()
return {
"name": quote["companyName"],
"price": float(quote["latestPrice"]),
"symbol": quote["symbol"]
}
except (KeyError, TypeError, ValueError):
return None

Answer 1

The error message is self-explanatory, it should be that line that is causing the problem:
current_price=lookup(row["symbol"]["price"])
Since you are reading from a table you should very likely be using row["symbol"], possibly transformed by some operation. You are addressing the field as if it were a dict. I don't know what your lookup does though. I would guess it takes just one argument so it could simply be something like that: current_price=lookup(row["symbol"])
Perhaps post the code for the lookup function if you don't manage to fix the issue.
PS: maybe the whole calculation could be done in SQL, probably a matter of JOINing two tables or something.