Re: Strange behavior using ModelForms

On Tue, Dec 18, 2012 at 4:11 PM, Francisco Vianna <francisco.v.vianna@gmail.com> wrote:

After some debugging, I realized they become the same after calling "is_valid" to the bound form. Now, I'm not sure if I am missing something conceptually about ModelForms binding.
Its very ackward to me that I can have a 'instance' field in a ModelForm, but can't distiguish the data after performing the validation. In my case specifically, I need to check first if the email provided by the user is valid, and only then check if its diferent from the instance's e-mail in order to set my flag. But I can't do it, or I will lose the new e-mail provided by the user in the form.

Can anyone enlighten this matter? Is this behavior expected?

Yes, is_valid() called on a model form updates the model form's instance in-place with the valid cleaned data. This is documented:

https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#the-is-valid-method-and-errors

Your form field's clean method would have access to the "old" value, since that runs before the new value has been fully validated and saved in the instance.

Karen
--
http://tracey.org/kmt/

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