data entry validation with Tkinter

[Martin Franklin]

Ken,

Take a look at the Pmw (Python Mega Widgets)
they've got an EntryField with validation plus some
built in validators (including dates, numbers, etc)
I use it for validating filenames.



Martin.








Ken Guest wrote:
> 
> hi,
> I'm trying to put together a python + tkinter app with data entry
> validation.
> What I have in mind is that the colour of the text changes depending
> on what the user has typed. (In otherwords the text is displayed in
> red if it is invalid, and in black if it is ok).
> I'd like to use regex (or the more up-to-date re strings) to specify
> what type of text is valid (cf my last query to the help mailing list).
> 
> At the moment, basic code that I have gotten to work looks like:
> 
> self.__entry = Entry(newframe, validate='key', vcmd='string is int %P',
> invcmd='bell')
> 
> attempts at specifying python procedures for vcmd and invcmd only seem
> to be called when the app in initialising and don't exactly work.
> For example, with
> 
> self.__entry = Entry(newframe, validate='key', vcmd=self.validate('%P'),
> invcmd=self.invalid())
> 
> the validate and invalid methods are called when the app starts up, but
> neither of those methods are called when any keys are pressed, and I'm
> really not sure that the second definition above is syntatically
> correct, even though the parser didn't catch any problems.
> 
> What I'd like to know is if what I am looking to do is in anyway
> possible, and if anybody has any pointers/ideas on how I could
> implement this functionality.
> Am I left to using TCL expressions for data entry validation (and if so,
> how do I do the above)
> 
> (I have done a number of searches on Google to see if anybody else
> may have run into these questions before but couldn't find anything
> of interest)
> 
> thanks,
> 
> Ken