Mike Driscoll: wxPython: Extracting XML from the RichTextCtrl

I recently came across a StackOverflow question where the fellow was asking how to get wxPython’s RichTextCtrl’s XML data so he could save it to a database. I don’t know much about this control, but after a quick Google search, I found an article from 2008 that gave me the information I needed. I took that example and cut it down to the following example:

import wx
import wx.richtext 
fromStringIOimportStringIO 
 
########################################################################class MyFrame(wx.Frame):
 
    #----------------------------------------------------------------------def__init__(self):
        wx.Frame.__init__(self, None, title='Richtext Test') 
        sizer = wx.BoxSizer(wx.VERTICAL)self.rt = wx.richtext.RichTextCtrl(self)self.rt.SetMinSize((300,200)) 
        save_button = wx.Button(self, label="Save")
        save_button.Bind(wx.EVT_BUTTON, self.on_save) 
        sizer = wx.BoxSizer(wx.VERTICAL)
        sizer.Add(self.rt, 1, wx.EXPAND|wx.ALL, 6)
        sizer.Add(save_button, 0, wx.EXPAND|wx.ALL, 6) 
        self.SetSizer(sizer)self.Show() 
 
    #----------------------------------------------------------------------def on_save(self, event):
        out = StringIO()
        handler = wx.richtext.RichTextXMLHandler()
        rt_buffer = self.rt.GetBuffer()
        handler.SaveStream(rt_buffer, out)
        out.seek(0)self.xml_content = out.read()printself.xml_content 
 
#----------------------------------------------------------------------if __name__ == "__main__":
    app = wx.App(False)
    frame = MyFrame()
    app.MainLoop()

Let’s break this down a bit. First we create our lovely application and add an instance of the RichTextCtrl widget to the frame along with a button for saving whatever we happen to write in said widget. Next we set up the binding for the button and layout the widgets. Lastly, we create our event handler. This is where the magic happens. Here we create the RichTextXMLHandler and grab the RichTextCtrl;s buffer so we can write out the data. But instead of writing to a file, we write to a file-like object, which is our StringIO instance. We do this so we can write the data to memory and then read it back out. The reason we do this is because the person on StackOverflow wanted a way to extract the XML that the RichTextCtrl generates and write it to a database. We could have written it to disk first and then read that file, but this is less messy and faster.

Note however that if someone had written a novel into the RichTextCtrl, then this would be a BAD idea! While it’s not likely that we would run out of room, there are certainly plenty of text files that exceed your computer’s memory. If you know that the file you are loading is going to take up a lot of memory, then you wouldn’t go this route. Instead you would read and write the data in chunks. Anyway, this code works for what we wanted to do. I hope you found this useful. It was certainly fun to figure out.