CODEWITHSUNDEEP
pythonmysqlflask
S. Pynewb22
S. Pynewb22

Reputation: 113

Flask Error when refreshing page ('NoneType')

Dear Python community,

I have encountered a problem that I can't get solved. I recently moved to a macOS Sierra Version 10.12.6.

All I am doing is connectedly to a MariaDB Mysql database. When staring the program the initial connection and response works and hence all the output is there, however when I refresh the page I get a "TypeError: 'NoneType' object is not iterable". If I restart the program in the terminal it will work again - until I refresh....

Here the code:

from dbhelper2 import DBHelper


app = Flask(__name__)
DB = DBHelper()

@app.route('/trtdtable')
def trtdtable():
    try:
        tabledata = DB.table_inputs()
    except Exception as e:
        print(e)
        tabledata = None
    return render_template("trtdtable.html", tabledata=tabledata)

second part (the DB helper)

import pymysql

# Connect to the database
connection =  pymysql.connect(host='localhost',user='root',password='',db='test',cursorclass=pymysql.cursors.DictCursor)

class DBHelper:

    def table_inputs(self):
        try:
            query = "SELECT PersonID, LastName, FirstName, Address, City FROM persons";
            with connection.cursor(pymysql.cursors.DictCursor) as cursor:
                cursor.execute(query)
            return cursor.fetchall()
        finally:
            connection.close()

and the HTML (in "trtdtable.html"):

<table id="customers">
            <tr>
              <th>ID</th>
              <th>Last Name Name</th>
              <th>First Name</th>
              <th>Address</th>
              <th>City</th>
            </tr>

           {% for row in tabledata %}
           <tr>
             <td>{{ row['PersonID'] }}</td>
             <td>{{ row['LastName'] }}</td>
             <td>{{ row['FirstName'] }}</td>
             <td>{{ row['Address'] }}</td>
             <td>{{ row['City'] }}</td>
           </tr>
           {% endfor %}

   </table>

Thank you for your help

Upvotes: 0

Views: 630

Answers (1)

Daniel Roseman
Daniel Roseman

Reputation: 599856

You're closing the connection after the query. Don't do that.

Also, never ever catch and swallow all exceptions. If you didn't have that blank except, Flask would have told you what the error was.

Upvotes: 1

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