Decorator
is a special function that do nothting on its own but can be used to change the behavior of other function.
——
e.g.,
from django.contrib.auth.decorators import login_required
def delete_bookmark(request, card_id):
# func definition
delete_bookmark = login_required(delete_bookmark)
card=Card.objects.get(name=query)
may result in exception Card.DoesNotExist
so,
card=get_object_or_404(Card,name-query)
will
1. use the same get() lookup
2. catch the DoesNotExist exception
3. trigger django.http.Http404, which will turn it into an HTTP 404 response.
def func(*args, **kwargs):
Python functions and methods can pass and receive arguments in two forms:
1. positional argument (the order is important)
2. keyword argument(names along with the values)
—
In Python, list and dictionary types are used for positional and keyword arguments respectively.
Passing a list as an argument and prefixing it with a single asterisk(*) will cause each item of the list in order. This will be used as a separate positional argument.
Passing a dictionary and prefixing it two asterisks(**) will cause the keys of the dictionary to be used as names for separate keyword arugments and the dictionary’s values to become the values of these arguments.
in urls.py
r(‘^card/(?P<year>\d{4})/(?P<month>\w{3})(?P<day>\d{2})/(?P<slug>[-\w]+)/$’, ‘card_detail’),
in views.py
def card_detail(request, year, month, day, slug):
# do render
————-
will return dictionary with keys are bracketed names and the values are the parts of the text that matched.
{{card.body|safe}}
Django template automatically “escapes” the contents of variables to prevent cross-site scripting attacks.
The safe filter lets you tell Django that you trust a variable and it doesn’t need a escaping.
–
other example of filter
{{card.body_html|truncatedwords_html:”50″|safe}}
{{card.pub_date|date:”F j, Y”}}
1. constants or list of choices
2. full list of fields
3. Meta class
4. __unicode__() method
5. save()
6. get_absolute_url()
7. any additional custom methods
lower()
is a Python string method to return a string converted to lowercase
—-
e.g.,
def get_absolute_url(self):
return “/card/%s/%s/” % (self.pub_date.strftime(“%Y/%b/%d”).lower(), self.slug)
The subclass needs a way to access parent class.
super
is the parent class.
—-
def save(self):
# do something specific customized actions for the model
super(Card, self).save() #perform parent class’s save
——-
editable=False
tells Django not to display the field when it automatically generate the form.
—
e.g.,
body_html=models.TextField(editable=False, blank=True)
