> On Jun 15, 2015, at 1:42 PM, Rick van Hattem (wolph) <[email protected]> > wrote: > > While I understand the rationale, it's not really possible due to the > underlying Python object: > >>> import datetime > >>> datetime.date() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: Required argument 'year' (pos 1) not found > >>> datetime.datetime() > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: Required argument 'year' (pos 1) not found >
A custom Django field would either assign initial values to classes that need it, or use classes that have their own initial values. The point is that the class itself should always exist in the field. > Note that you can easily support it by having something like this: > > class Question(models.Model): > pub_date = models.DateField(default=datetime.date.today, blank=True) > > Right. I’m trying to avoid this situation, as this adds a lot of code - I have dozens of custom fields instantiated hundreds of times in an app, with a lot of initialization data each. It also requires the knowledge of which internal class that the field uses. So, I have a common get/set interface for each custom field, so I don’t need to know which class that a field uses, as long as I interface with it properly. -bobby > > ~wolph > > On Monday, June 15, 2015 at 7:52:13 AM UTC+2, Bobby Mozumder wrote: > Hi all, > > Here’s an issue of usability that if fixed could make usage of custom fields > simpler. > > Right now fields don’t allow a built-in defaults, and you need to explicitly > set the default parameter for model fields. The problem is that this adds a > ton of boilerplate code. > > Using the Polls tutorial example, if I do: > > >>> from polls.models import Question, Choice > >>> q = Question() > > By default it’s always <class 'NoneType’>: > > >>> type(q.pub_date) > <class 'NoneType'> > > The pub_date should always be a type <class 'datetime.datetime'>. If this > was defined in the model constructor, then we could start to access the > datetime.datetime class immediately, to assign data. If I had a custom > datetime.datetime class, I could possibly do this immediately: > > >>> q = Question() > >>> q.pub_date.month = 11 > >>> q.pub_date.day = 26 > >>> q.pub_date.year = 2016 > >>> q.save() > > But right it would give the following error: > > >>> q.pub_date.year = 2016 > Traceback (most recent call last): > File "<console>", line 1, in <module> > AttributeError: 'NoneType' object has no attribute 'year' > > Is this a reasonable request? > > I’m able to do something like this now with my own custom fields that derive > from models.SubfieldBase, but that class is deprecated, and the new 1.8 model > initializer doesn’t do this anymore. > > Thank you, > > -bobby > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected] > <mailto:[email protected]>. > To post to this group, send email to [email protected] > <mailto:[email protected]>. > Visit this group at http://groups.google.com/group/django-developers > <http://groups.google.com/group/django-developers>. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/43d136dd-b8d7-45fe-91af-1863cb5aa205%40googlegroups.com > > <https://groups.google.com/d/msgid/django-developers/43d136dd-b8d7-45fe-91af-1863cb5aa205%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout > <https://groups.google.com/d/optout>. -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/CD62262A-302A-41F0-AF26-A1F34EC45D34%40gmail.com. For more options, visit https://groups.google.com/d/optout.
