第一次查询后连接游标返回 None

Question

I'm a newbie in Python and working for the first time with Django.

My connection.cursor() return None after first call.

Here's my problem :

def request_pc(request):
    body = request.body.decode('utf-8')
    data = json.loads(body)
    if not firstCheck(data['testValue1']):
        return JsonResponse({'error': 'foo'})

    data = secondCheck(data['testValue2'])
    if not data:
        return JsonResponse({'error': 'foo'})

def first_check(testValue1):
    with connection.cursor() as cursor:
        row_count = cursor.execute('''
            SELECT 1
            FROM foo_session
            WHERE value = %s
        ''', [testValue1])
    if 1 == row_count:
        return True
    return False


def second_check(testValue2):
    with connection.cursor() as cursor:
        row_count = cursor.execute('''
            SELECT *
            FROM core_foo2
            WHERE value = %s
        ''', [testValue2])
    res = cursor.fetchone()
    pprint(row_count) // return 1
    pprint(res) // return empty
    if not res:
        return False
    return res

first_check return data and everything is ok

but

second_check return row_count = 1 and data is empty

I have the same problem if I copy/paste the first query on the second...

Thank you

Answer 1

You are here "closing" the cursor before fetching the entry. By using .fetcone() in the with clause, you prevent that:

def second_check(testValue2):
    with connection.cursor() as cursor:
        row_count = cursor.execute('''
            SELECT *
            FROM core_foo2
            WHERE value = %s
        ''', [testValue2])
        # ↓ in the with clause
        
    pprint(row_count) # return 1
    pprint(res) # return empty
    if not res:
        return False
    return res