As pointed out in this answer, Django 1.9 added the Field.disabled attribute:
The disabled boolean argument, when set to True, disables a form field using the disabled HTML attribute so that it won’t be editable by users. Even if a user tampers with the field’s value submitted to the server, it will be ignored in favor of the value from the form’s initial data.
With Django 1.8 and earlier, to disable entry on the widget and prevent malicious POST hacks you must scrub the input in addition to setting the readonly
attribute on the form field:
class ItemForm(ModelForm):
def __init__(self, *args, **kwargs):
super(ItemForm, self).__init__(*args, **kwargs)
instance = getattr(self, 'instance', None)
if instance and instance.pk:
self.fields['sku'].widget.attrs['readonly'] = True
def clean_sku(self):
instance = getattr(self, 'instance', None)
if instance and instance.pk:
return instance.sku
else:
return self.cleaned_data['sku']
Or, replace if instance and instance.pk
with another condition indicating you're editing. You could also set the attribute disabled
on the input field, instead of readonly
.
The clean_sku
function will ensure that the readonly
value won't be overridden by a POST
.
Otherwise, there is no built-in Django form field which will render a value while rejecting bound input data. If this is what you desire, you should instead create a separate ModelForm
that excludes the uneditable field(s), and just print them inside your template.
Concatenating the querysets into a list is the simplest approach. If the database will be hit for all querysets anyway (e.g. because the result needs to be sorted), this won't add further cost.
from itertools import chain
result_list = list(chain(page_list, article_list, post_list))
Using itertools.chain
is faster than looping each list and appending elements one by one, since itertools
is implemented in C. It also consumes less memory than converting each queryset into a list before concatenating.
Now it's possible to sort the resulting list e.g. by date (as requested in hasen j's comment to another answer). The sorted()
function conveniently accepts a generator and returns a list:
result_list = sorted(
chain(page_list, article_list, post_list),
key=lambda instance: instance.date_created)
If you're using Python 2.4 or later, you can use attrgetter
instead of a lambda. I remember reading about it being faster, but I didn't see a noticeable speed difference for a million item list.
from operator import attrgetter
result_list = sorted(
chain(page_list, article_list, post_list),
key=attrgetter('date_created'))
Best Answer
When defining your fields in models.py:
Bookmark this link:
https://docs.djangoproject.com/en/dev/ref/models/fields/#help-text
I find myself referring to it all the time (not just for help_text, but for everything to do with model fields)!