How to write wxListBox entries into a .txt file in python

I'm trying to program a wxFormBuilder interface to write text from a wxListBox into a text file. My current code:

def clickSave (self, parent):
    dialog = wx.FileDialog(None, "Choose a file", os.getcwd(), "", "*.*", wx.SAVE)
    if dialog.ShowModal() == wx.ID_OK:
        fn = dialog.GetPath() 
        fh = open(fn, "w")
        for i in range(self.m_listBox4.GetCount()):
            listBox = self.m_listBox4.GetString(i) + "\n"
        fh.write(listBox)
        fh.close()

Currently this code saves only the last entry in the listbox instead of all of the entries. I'm also having trouble importing lists from a text file into the wxListBox. With the code I have, I'm getting a "TypeError: String or Unicode type required" error:

def clickOpen(self, event):
    dialog = wx.FileDialog(None, "Choose a file", os.getcwd(), "", "*.*", wx.OPEN)

    if dialog.ShowModal() == wx.ID_OK:
        stockinfo = []
        fn = dialog.GetPath()
        fh = open(fn, "r") 
        csv_fh = csv.reader(fh)
        for row in csv_fh:
            stockinfo.append(row)
        fh.close()
        for rows in stockinfo:
            self.m_listBox4.Append(rows)

Solution

In the

for i in range(self.m_listBox4.GetCount()):
    listBox = self.m_listBox4.GetString(i) + "\n"

you always overwrite the content of listBox variable, therefore only the last row stays in. You probably wanted to do:

    listBox += self.m_listBox4.GetString(i) + "\n"

However, concatenating strings is very inefficient. You should be doing something like:

for i in range(self.m_listBox4.GetCount()):
    fh.write(self.m_listBox4.GetString(i))
    fh.write("\n")

As for the other one:

for row in csv_fh:
    stockinfo.append(row)

Here, row is not a String or Unicode, but a sequence. You are just putting this sequence into a list and trying to add it to the list box later. Change

   self.m_listBox4.Append(str(rows))

just to see what it does.