On Wed, 2008-11-26 at 19:50 -0800, nbv4 wrote: > I'm new to django, and I'm having a problem setting up a model. > > I have a model which has about 12 decimal fields and two integer > fields. Each field, when displayed, will always be blank if the value > is zero. In other words, "0" or "0.0" will never be displayed, either > when the object is outputted to the page, or in a form derived from > that model. Whats the best way to set up each field, in regards to > null=True/False, blank=True/False default=0/Null, etc. > > I want to be able to create a form derived from this model, and I want > all the fields in that form to start out as blank, so I guess I want > "default=Null", but doing this creates a NULL in the database, which > screws up numerical calculations.
Since "blank" isn't a valid concept for a numerical field, what you need to do is write your own form field class that knows how to convert between "0" and blank for rendering purposes (it will need to use a text widget of some kind for the rendering) and back for validation. You won't be able to achieve this affect automatically, since it doesn't normally make sense. What happens if somebody deliberately enters "0" into a field for example? When you redisplay the form, to correct some other error, their input has been lost. It will make it hard to tell the difference between fields with required values and a zero entered in them and field with required values that haven't been filled in yet. As for the specifics, if you really want to do this, have a read of django/forms/fields.py to see how Field classes are implemented and django/forms/widgets.py for the corresponding widgets. That will give you some ideas for how to do this. Regards, Malcolm --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
