when i run the code i get this error UnboundLocalError: local variable 'cursor' referenced before assignment

Question

So I am a newbie but working on flask/MYSQL

I am receiving this error (UnboundLocalError: local variable 'cursor' referenced before assignment)

After hours of playing with the code and research I need your help.

how can i solve this error

This is my file, please let me know if there's anything else I need to share. thank you

import pymysql
from app import app
from db_config import mysql
from flask import flash, session, render_template, request, redirect, url_for
#from werkzeug import generate_password_hash, check_password_hash
from werkzeug.security import generate_password_hash, check_password_hash
        
@app.route('/add', methods=['POST'])
def add_product_to_cart():
    cursor = None
    try:
        _quantity = int(request.form['quantity'])
        _code = request.form['code']
        # validate the received values
        if _quantity and _code and request.method == 'POST':
            conn = mysql.connect()
            cursor = conn.cursor(pymysql.cursors.DictCursor)
            cursor.execute("SELECT * FROM product WHERE code=%s", _code)
            row = cursor.fetchone()
            
            itemArray = { row['code'] : {'name' : row['name'], 'code' : row['code'], 'quantity' : _quantity, 'price' : row['price'], 'image' : row['image'], 'total_price': _quantity * row['price']}}
            
            all_total_price = 0
            all_total_quantity = 0
            
            session.modified = True
            if 'cart_item' in session:
                if row['code'] in session['cart_item']:
                    for key, value in session['cart_item'].items():
                        if row['code'] == key:
                            #session.modified = True
                            #if session['cart_item'][key]['quantity'] is not None:
                            #   session['cart_item'][key]['quantity'] = 0
                            old_quantity = session['cart_item'][key]['quantity']
                            total_quantity = old_quantity + _quantity
                            session['cart_item'][key]['quantity'] = total_quantity
                            session['cart_item'][key]['total_price'] = total_quantity * row['price']
                else:
                    session['cart_item'] = array_merge(session['cart_item'], itemArray)

                for key, value in session['cart_item'].items():
                    individual_quantity = int(session['cart_item'][key]['quantity'])
                    individual_price = float(session['cart_item'][key]['total_price'])
                    all_total_quantity = all_total_quantity + individual_quantity
                    all_total_price = all_total_price + individual_price
            else:
                session['cart_item'] = itemArray
                all_total_quantity = all_total_quantity + _quantity
                all_total_price = all_total_price + _quantity * row['price']
            
            session['all_total_quantity'] = all_total_quantity
            session['all_total_price'] = all_total_price
            
            return redirect(url_for('.products'))
        else:           
            return 'Error while adding item to cart'
    except Exception as e:
        print(e)
    finally:
        cursor.close() 
        conn.close()
        
@app.route('/')
def products():
    try:
        conn = mysql.connect()
        cursor = conn.cursor(pymysql.cursors.DictCursor)
        cursor.execute("SELECT * FROM product")
        rows = cursor.fetchall()
        return render_template('products.html', products=rows)
    except Exception as e:
        print(e)
    finally:
        cursor.close() 
        conn.close()

@app.route('/empty')
def empty_cart():
    try:
        session.clear()
        return redirect(url_for('.products'))
    except Exception as e:
        print(e)

@app.route('/delete/<string:code>')
def delete_product(code):
    try:
        all_total_price = 0
        all_total_quantity = 0
        session.modified = True
        
        for item in session['cart_item'].items():
            if item[0] == code:             
                session['cart_item'].pop(item[0], None)
                if 'cart_item' in session:
                    for key, value in session['cart_item'].items():
                        individual_quantity = int(session['cart_item'][key]['quantity'])
                        individual_price = float(session['cart_item'][key]['total_price'])
                        all_total_quantity = all_total_quantity + individual_quantity
                        all_total_price = all_total_price + individual_price
                break
        
        if all_total_quantity == 0:
            session.clear()
        else:
            session['all_total_quantity'] = all_total_quantity
            session['all_total_price'] = all_total_price
        
        #return redirect('/')
        return redirect(url_for('.products'))
    except Exception as e:
        print(e)
        
def array_merge( first_array , second_array ):
    if isinstance( first_array , list ) and isinstance( second_array , list ):
        return first_array + second_array
    elif isinstance( first_array , dict ) and isinstance( second_array , dict ):
        return dict( list( first_array.items() ) + list( second_array.items() ) )
    elif isinstance( first_array , set ) and isinstance( second_array , set ):
        return first_array.union( second_array )
    return False        
        
if __name__ == "__main__":
    app.run(debug=True)

Answer 1

In the products function, if there is an exception creating the connection, then execution jumps to the finally: block, so cursor = ... is never executed, thus cursor.close() fails.

One possible solution: add cursor = None above, and then in the finally: block: if cursor is not None: cursor.close()