instance has no attribute (python)

Question

I have a weird issue, which is probably easy to resolve.

I have a class Database with an __init__ and an executeDictMore method (among others).

class Database():
 def __init__(self, database, server,login, password ):
 self.database = database
 my_conv = { FIELD_TYPE.LONG: int }
 self.conn = MySQLdb.Connection(user=login, passwd=password, db=self.database, host=server, conv=my_conv)
 self.cursor = self.conn.cursor()
 def executeDictMore(self, query):
 self.cursor.execute(query)
 data = self.cursor.fetchall()
 if data == None :
 return None
 result = []
 for d in data:
 desc = self.cursor.description
 dict = {}
 for (name, value) in zip(desc, d) :
 dict[name[0]] = value
 result.append(dict)
 return result

Then I instantiate this class in a file db_functions.py :

from Database import Database
db = Database()

And I call the executeDictMore method from a function of db_functions :

def test(id):
 query = "SELECT * FROM table WHERE table_id=%s;" %(id)
 return db.executeDictMore(query)

Now comes the weird part. If I import db_functions and call db_functions.test(id) from a python console:

import db_functions
t = db_functions.test(12)

it works just fine. But if I do the same thing from another python file I get the following error :

AttributeError: Database instance has no attribute 'executeDictMore'

I really don't understand what is going on here. I don't think I have another Database class interfering. And I append the folder where the modules are in sys.path, so it should call the right module anyway.

If someone has an idea, it's very welcome.

• Torxed: Can you please post the code of "from another python file" so we can see how you utelize the db instance? Can I assume you're importing Database.py multiple times? In that case there could be an issue where db is already defined in the global scope and cause some shady issues. (just brainstorming)

Answer 1

You have another Database module or package in your path somewhere, and it is getting imported instead.

To diagnose where that other module is living, add:

import Database
print Database.__file__

before the from Database import Database line; it'll print the filename of the module. You'll have to rename one or the other module to not conflict.

Answer 2

You could at least try to avoid SQL injection. Python provides such neat ways to do so:

def executeDictMore(self, query, data=None):
 self.cursor.execute(query, data)

and

def test(id):
 query = "SELECT * FROM table WHERE table_id=%s"
 return db.executeDictMore(query, id)

are the ways to do so.

Sorry, this should rather be a comment, but an answer allows for better formatting. Iam aware that it doesn't answer your question...

Answer 3

You should insert (not append) into your sys.path if you want it first in the search path:

sys.path.insert(0, '/path/to/your/Database/class')

Answer 4

Im not too sure what is wrong but you could try passing the database object to the function as an argument like db_functions.test(db, 12) with db being your Database class

• Torxed: I thought of this too, but you shouldn't need to because once imported and instanciated the db object should be accessible from any module importing the Database.py file and accessing the db object.