Re: Cursor Not Passed Properly Inter-Module

Rich,

My observations:

You seen to be wanting to call methods on class DBtools without first
creating an instance.  You appear to call the DBtools constructor (i.e.,
DBtools().CreateDB(...))  in OnNewMod() but don't save a reference.
Then in OnSaveMod() you invoke DBtools.cur.exectue(...), but you don't
appear to specify the instance of DBtools to use.

Bill
-- 
William J. Chapman
1209 N. Guam St.
Ridgecrest CA 93555
760-371-5501


On Tue, 2006-11-28 at 16:55 -0800, Rich Shepard wrote:
> On Tue, 28 Nov 2006, Adrian Klaver wrote:
> 
> > I think I see what is happening. In your first post dba creates an
> > instance of DBtools().CreateDB(). This has a cursor associated with via
> > the if statement. The cursor executes the CREATE TABLE statement. In the
> > OnSaveMod there is no creation of a DBtools instance. Calling
> > DBTools.cur.execute fails because at the top level of the class cur=None.
> > With what you have shown cur is only available through the CreateDB
> > function.
> 
>    And I think that I'm following you. But, I don't see the solution. Here's
> more detail.
> 
>    In the calling module, modelPage.py, two of the bound (to buttons) methods
> are:
> 
>    def OnNewMod(self, event):
>      newName = functions.newFile(self)
>      self.tcName.SetValue(self.appData.projname)
>      DBtools().CreateDB(self.appData.dbFileName)
> 
> and
> 
>    def OnSaveMod(self, event):
>      self.modName = self.tcName.GetValue()
>      self.modDesc = self.tcDesc.GetValue()
>      self.modType = self.rb.GetString(self.rb.GetSelection())
>      self.knowlEng = self.keName.GetValue()
>      self.method = self.agent.GetSelection()
>      DBtools.cur.execute("insert or replace into model (model_name, \
>                           model_desc, model_type, \
>                           keName, agent) values (self.modnName, \
>                           self.modDesc, self.modType, \
>                           self.knowlEng, self.method)")
>      DBtools().SaveDB(self.appData.dbFileName)
> 
>    So, the first is calling a method in the class DBtools, which requires the
> cursor, and the second is trying to directly call the cursor.
> 
>    Based on your message, I modified dbMethods.py so the connection and
> cursor are specified in each method. For example,
> 
>    def CreateDB(self, dbFileName):
>      self.con = sqlite3.connect(self.appData.dbFileName)
>      self.cur = self.con.cursor()
> 
> and
> 
>    def SaveDB(self, dbFileName):
>      self.con = sqlite3.connect(self.appData.dbFileName)
>      self.cur = self.con.cursor()
>      self.con.commit()
> 
>    But, the error shows up on the line before the call to DBtools.SaveDB(). I
> read the error message telling me that the calling module does not see the
> cursor in the imported module. If that's the case, I have no idea how to
> make the cursor visible to the caller. In the class DBtools(), the
> connection and cursor cannot be created until the database name is provided.
> 
>    Should I put the connection and cursor creation also in config.py with its
> configData() class that's imported by all other modules?
> 
> Thanks,
> 
> Rich
> 
> 
>