Sample Django project to show Django bug https://code.djangoproject.com/ticket/11390
If you use a callable as default value on a model field, it gets called 3 times.
Sample code to reproduce this:
def get_title(call_count=[0]):
call_count[0] += 1
n = call_count[0]
msg = 'get_title call #{}'.format(n)
print msg
return msg
class Article(models.Model):
title = models.CharField(max_length=50, default=get_title)
This repo contains a Django project containing that model.
To show 2 seperate calls to get the default field value, run/execfile show_bug.py from a ./manage shell:
In [1]: from django.forms.models import modelform_factory
In [2]: from cad.models import Article
In [3]: article_modelform = modelform_factory(Article, fields=('title',))
In [4]: form = article_modelform()
get_title call #1
In [5]: form.as_p()
get_title call #2
Out[5]: u'<p><label for="id_title">Title:</label> <input id="id_title" maxlength="50" name="title" type="text" value="get_title call #2" /><input id="initial-id_title" name="initial-title" type="hidden" value="get_title call #2" /></p>'
django/contrib/admin/options.py:ModelAdmin.changeform_view
one call for each of these 2 lines
form = ModelForm(initial=initial)
formsets, inline_instances = self._create_formsets(request, self.model(), change=False)
django/forms/forms.py:BoundField
BoundField.__str__
BoundField.as_widget
BoundField.value