I'd like to use url arguments in views (not templates, I know how to do that).
So is it possible to use them like:
def item_link(self, item):
return mainpage_url_name + "%s/%i" % (item.slug, item.cid)
mainpage_url_name - is of course defined in url patterns (as name variable)
I'm a total newb in Django...
Thanks
First you should use names for your url patterns as documented here.
Then you can use reverse() to use these names in your views or methods.
Following your comments you are using the syndication framework.
Therefore you should make sure that you define get_absolute_url() for you models, ideally using the permalink decorator (for a clean reversing of your urls).
Looking at the example from Django's docs that should be all that's necessary.
To specify the contents of <link>, you
have two options. For each item in
items(), Django first tries calling
the item_link() method on the Feed
class. In a similar way to the title
and description, it is passed it a
single parameter, item. If that method
doesn't exist, Django tries executing
a get_absolute_url() method on that
object.
Related
I have two urls in dispatcher pointing the same view
path('posts/top/', posts, name='top'),
path('posts/new/', posts, name='new'),
I want view start as follows:
def posts(request, ordering):
...
I guess, to pass top and new as a parameter it should be something like:
path('posts/<ordering:top>/', posts, name='top'),
path('posts/<ordering:new>/', posts, name='new'),
But it gives me:
django.core.exceptions.ImproperlyConfigured: URL route 'posts/<ordering:top>/' uses invalid converter 'ordering'.
So, as a work around I use this, but it looks a little bit dirty:
path('posts/top/', posts, name='top', kwargs={'order': 'top'}),
path('posts/new/', posts, name='new', kwargs={'order': 'top'}),
What is the right way to do it?
You've misunderstood the way path converters work. The first element is the type, which here is str, and the second is the parameter name to use when calling the view. At this point you don't constrain the permissible values themselves. So your path would be:
path('posts/<str:ordering>/', posts, name='posts')
and when you come to reverse you would pass in the relevant parameter:
{% url 'posts' ordering='top' %}
If you really want to ensure that people can only pass those two values, you can either check it programmatically in the view, or you can use re_path to use regex in your path:
re_path(r'^posts/(?P<ordering>top|new)/$', posts, name='posts')
I am working on a simple project on Django. Currently the views that I am implementing always return a hardcode path:
def temp_view(request):
...
return render("app/detail.html")
or
def temp_view_2(request):
...
return redirect("/app/view2")
What I want to do is to get rid of the hardcode URL (for view URL and the template URL). Is there a proper way to do that?
Thanks.
Django provides a few different methods. In a view, the django.core.urlresolvers.reverse() function is most often used. A full discussion of this problem and the options provided by Django is here:
https://docs.djangoproject.com/en/dev/topics/http/urls/#reverse-resolution-of-urls
I'm a newbie in Django and in WordPress if you create a Post called "hello world" then the URL by default will be like
wordpress.com/2012/07/05/hello-world/
and if you create another post with the same name it will be
wordpress.com/2012/07/05/hello-world-2/
I want to achieve the same in Django and I was thinking to create a sample urlconf like this
(r'^articles/(\d{4})/(\d{2})/(?P<name>\w+)', 'article.views.article_detail')
and in the views break down the name and iterate through all the items and match the name.
But the problem with will be that I won't be able to reference posts dynamically. For e.g. if I was to link the a hello world post I would need to find out how many posts with the same name exist already and then append the additional number to it which is inefficient.
So what's the best way to do this in Django?
See the documentation for Django's {{ url }} template tag. It lets you pass it a view name and parameters, and automatically generates the correct URL for you.
You can take care of appending numbers to each post's name in the function that generates its slug - you could have a look at django-autoslug
When I read Django code sometimes, I see in some templates reverse(). I am not quite sure what this is but it is used together with HttpResponseRedirect. How and when is this reverse() supposed to be used?
reverse() | Django documentation
Let's suppose that in your urls.py you have defined this:
url(r'^foo$', some_view, name='url_name'),
In a template you can then refer to this url as:
<!-- django <= 1.4 -->
link which calls some_view
<!-- django >= 1.5 or with {% load url from future %} in your template -->
link which calls some_view
This will be rendered as:
link which calls some_view
Now say you want to do something similar in your views.py - e.g. you are handling some other URL (not /foo/) in some other view (not some_view) and you want to redirect the user to /foo/ (often the case on successful form submission).
You could just do:
return HttpResponseRedirect('/foo/')
But what if you want to change the URL in the future? You'd have to update your urls.py and all references to it in your code. This violates the DRY (Don't Repeat Yourself) principle and the whole idea of editing in one place only - which is something to strive for.
Instead, you can say:
from django.http import HttpResponseRedirect
from django.urls import reverse
return HttpResponseRedirect(reverse('url_name'))
This looks through all URLs defined in your project for the URL defined with the name url_name and returns the actual URL /foo/.
This means that you refer to the URL only by its name attribute - if you want to change the URL itself or the view it refers to you can do this by editing one place only - urls.py.
The existing answers are quite clear. Just in case you do not know why it is called reverse: It takes an input of a url name and gives the actual url, which is reverse to having a url first and then give it a name.
Existing answers did a great job at explaining the what of this reverse() function in Django.
However, I'd hoped that my answer shed a different light at the why: why use reverse() in place of other more straightforward, arguably more pythonic approaches in template-view binding, and what are some legitimate reasons for the popularity of this "redirect via reverse() pattern" in Django routing logic.
One key benefit is the reverse construction of a url, as others have mentioned. Just like how you would use {% url "profile" profile.id %} to generate the url from your app's url configuration file: e.g. path('<int:profile.id>/profile', views.profile, name="profile").
But as the OP have noted, the use of reverse() is also commonly combined with the use of HttpResponseRedirect. But why?
I am not quite sure what this is but it is used together with HttpResponseRedirect. How and when is this reverse() supposed to be used?
Consider the following views.py:
from django.http import HttpResponseRedirect
from django.urls import reverse
def vote(request, question_id):
question = get_object_or_404(Question, pk=question_id)
try:
selected = question.choice_set.get(pk=request.POST['choice'])
except KeyError:
# handle exception
pass
else:
selected.votes += 1
selected.save()
return HttpResponseRedirect(reverse('polls:polls-results',
args=(question.id)
))
And our minimal urls.py:
from django.urls import path
from . import views
app_name = 'polls'
urlpatterns = [
path('<int:question_id>/results/', views.results, name='polls-results'),
path('<int:question_id>/vote/', views.vote, name='polls-vote')
]
In the vote() function, the code in our else block uses reverse along with HttpResponseRedirect in the following pattern:
HttpResponseRedirect(reverse('polls:polls-results',
args=(question.id)
This first and foremost, means we don't have to hardcode the URL (consistent with the DRY principle) but more crucially, reverse() provides an elegant way to construct URL strings by handling values unpacked from the arguments (args=(question.id) is handled by URLConfig). Supposed question has an attribute id which contains the value 5, the URL constructed from the reverse() would then be:
'/polls/5/results/'
In normal template-view binding code, we use HttpResponse() or render() as they typically involve less abstraction: one view function returning one template:
def index(request):
return render(request, 'polls/index.html')
But in many legitimate cases of redirection, we typically care about constructing the URL from a list of parameters. These include cases such as:
HTML form submission through POST request
User login post-validation
Reset password through JSON web tokens
Most of these involve some form of redirection, and a URL constructed through a set of parameters. Hope this adds to the already helpful thread of answers!
This is an old question, but here is something that might help someone.
From the official docs:
Django provides tools for performing URL reversing that match the
different layers where URLs are needed: In templates: Using the url
template tag. In Python code: Using the reverse() function. In higher
level code related to handling of URLs of Django model instances: The
get_absolute_url() method.
Eg. in templates (url tag)
2012 Archive
Eg. in python code (using the reverse function)
return HttpResponseRedirect(reverse('news-year-archive', args=(year,)))
The function supports the dry principle - ensuring that you don't hard code urls throughout your app. A url should be defined in one place, and only one place - your url conf. After that you're really just referencing that info.
Use reverse() to give you the url of a page, given either the path to the view, or the page_name parameter from your url conf. You would use it in cases where it doesn't make sense to do it in the template with {% url 'my-page' %}.
There are lots of possible places you might use this functionality. One place I've found I use it is when redirecting users in a view (often after the successful processing of a form)-
return HttpResponseRedirect(reverse('thanks-we-got-your-form-page'))
You might also use it when writing template tags.
Another time I used reverse() was with model inheritance. I had a ListView on a parent model, but wanted to get from any one of those parent objects to the DetailView of it's associated child object. I attached a get__child_url() function to the parent which identified the existence of a child and returned the url of it's DetailView using reverse().
There is a doc for that
https://docs.djangoproject.com/en/dev/topics/http/urls/#reverse-resolution-of-urls
it can be used to generate an URL for a given view
main advantage is that you do not hard code routes in your code.
The reverse() is used to adhere the django DRY principle i.e if you change the url in future then you can reference that url using reverse(urlname).
I'm creating an app in which many urls are using a pattern like /foo/bar/<object_id>/<object_name_slug>/, like many applications (SO included), which is itself a straightforward pattern to implement. However, I don't want to just blindly ignore the contents of the slug field and open the app up to stupid stuff like people distributing a doctored URL (e.g. the recently popular http://www.independent.co.uk/life-style/food-and-drink/utter-PR-fiction-but-people-love-this-shit-so-fuck-it-lets-just-print-it-2269573.html).
My plan is to validate the slug an issue a redirect to the correct URL if someone reaches a page via a bad slug (again, like SO). This would be trivial to implement in the view, but since this will be a pattern used on many views, I'd like to factor it out into something reusable--probably a decorator or a middleware.
What's the best way to do this? Could a decorator determine which url pattern was matched by a particular request so that it could generate a reverse if necessary?
Thanks for the ideas.
You could use middleware for this. Cross-check the Entry id (let's just suppose you use the Entry model for content. The ID in the URL you mention would be 2269573 for example) with its slug (supposing your Entry model has a slug field of course). If the slug is incorrect, just redirect to the correct page.
In order to do this, create a class, and give it the process_request method. Then add this class to your settings' MIDDLEWARE_CLASSES.
The process_request takes a "request" parameter (a HttpRequest object), and this object has a path attribute that will give you the URL that was requested.
Based on that URL you can define the actions to be undertaken.
The method of your middleware class should return None or a HttpRequest object. The latter can be a django.http.HttpResponseRedirect instance, meaning you can redirect to the correct URL (thereby ignoring the incorrect slug).