Great proposal and I'd love it on forms. I'm not sure about models, though.
I always use forms for sanitization.
On Wednesday, 25 March 2015 10:37:43 UTC+1, guettli wrote:
>
> Up to now the validation/cleaning of a attribute can not access the
> value of an other attribute.
>
> The work around is to override the clean() method of the form/model.
>
> A team mate and I talked about it, and we asked ourself, if
> a two phase cleaning would help here.
>
> Our idea:
>
> - The first clean phase works like the current implementation
>
> - The second clean phase is optional and does nothing except the user
> implements it.
>
> - In the second clean phase your are allowed to peek into
> the results of the first clean phase.
> The clean method for the second phase would need to get the other
> values passed in.
>
>
> I would like to have this on model level, not only for forms.
>
> Example:
>
> class Issue(models.Model):
> state=models.CharField(choices=[('in_progress', 'In progress'),
> ('wait_until_due_date', 'Wait until due date')])
> due_date=models.DateField(null=True)
>
>
> We want to implement this constraint:
>
> - due date must be set, if the state is "wait_until_due_date".
> - due date must not be set, if state is different from
> "wait_until_due_date".
>
> We know that we can use the clean() method of the model, but a field based
> solution would
> be more preferred.
>
> class Issue(models.Model):
> state = models.CharField(choices=[('in_progress', 'In progress'),
> ('wait_until_due_date', 'Wait until due date')])
> due_date = models.DateField(null=True,
> validators2=[check_state_and_due_date_match])
>
> def check_state_and_due_date_match(due_date, all_fields):
> state = all_fields['state']
> if due_date:
> if state != 'wait_until_due_date':
> raise ValidationError('If due date is set, state must be
> "wait_until_due_date"')
> return
> if state != 'wait_until_due_date':
> raise ValidationError('If no due date is set, state must be
> "wait_until_due_date")
>
>
> Open questions: I am unsure if this should be used only for validation, or
> if it should be possible
> to alter values, too.
>
> What do you think?
>
> Other solutions or improvements?
>
> Regards,
> Thomas Güttler
>
>
>
> --
> Thomas Güttler
> http://thomas-guettler.de/
>
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