Question

I want to send a session object of sqlalchemy to a function of another class .

From class OraDialog‘s function oraconnect to class oraconn‘s assign function .

Actually My need is to use the session object in oraconn‘s another function map

I can’t send the session object directly to map function because it is a slot – it is triggered before .
I intended to define the assign function primarily to get the session object.

The Error : ( including print statements )

<sqlalchemy.orm.session.Session object at 0x030808F0>
<sqlalchemy.orm.session.Session object at 0x030808F0>
This is in assign
None
This is in map
Traceback (most recent call last):
File "C:\Users\Arul\Desktop\dbvis\oraconn.py", line 44, in map
for t in self.s.query(tables):
AttributeError: 'NoneType' object has no attribute 'query'

The oraconn class’s assign and map functions :

def assign(self,s):
    self.s=s
    print self.s
    print "This is in assign"
def map(self):
    print self.s
    print "This is in map"
    self.table_no=0
    for t in self.s.query(tables):
        self.table_no=self.table_no+1
        table_list.append(t.table_name)
    self.item=QtCore.QStringList()
    for c in self.s.query(columns):
        self.item.append(c.column_name)
    self.ui.list_col.addItems(self.item)

SO ,
The assign function receives the object properly . But the map function can’t use it – It says Nonetype

My Question :
Two functions of same class can’t use an object ?

I must have done something silly – so plz point out……

( I’m using windows7 / python 2.6 / PyQt4 /sqlalchemy /cx_oracle)

Edit :
The calling class :

class OraDialog(QtGui.QDialog):
def __init__(self,parent=None):
    QtGui.QDialog.__init__(self,parent)
    self.odia=Ui_Dialog()
    self.odia.setupUi(self)
    self.uiobj=oraconn()
    QtCore.QObject.connect(self.odia.but_con,QtCore.SIGNAL('clicked()'),self.uiobj.oraconnect)
def oraconnect(self):
    self.setVisible(0)
    eng_str="oracle://"+self.odia.line_user.text()+":"+self.odia.line_pass.text()+"@localhost:1521/"+self.odia.line_sid.text()+"?mode="+self.odia.line_role.text()
    engine_str=str(eng_str)
    engine=create_engine(engine_str)
    Session=sessionmaker(engine)
    self.s=Session()
    print self.s

Problem Solved :
The problem is – i’ve created two instances and passed from one to another .

Corrected code :

oraconn.assign(myapp,self.s)

where
oraconn -> class
assign -> function of oraconn
myapp -> instance of oraconn , declared for main application
self.s -> the argument i wanted to pass

Thank you Kirk ….

Answer 1

If you’re using Qt, then this is likely a GUI app. Maybe there are threading issues; maybe self refers to different objects. It’s hard to tell with only what you’ve given us. Before you go any further, add:

print self

near the top of each method. At least then you can confirm whether both are operating on the same object.

---

In OraDialog.init, you’re saying self.uiobj=oraconn(). Is that the object that’s giving you problems? If so: notice that you’re creating at as an instance variable, so that each OraDialog object has a different .uiobj object. Could you try making that a class variable by writing:

class OraDialog(QtGui.QDialog):
    uiobj = oraconn()
    def __init__() [...]

instead? That is, define uiobj as belonging to all instances of the class, not just one instance.