I am working on a django project which have a posts page. I have its url as follows:
path('posts/<str:sort>', views.posts, name='posts'),
and this is what its view looks like:
def posts(request,sort)
b=""
if b=="time":
posts=Post.objects.all().order_by(b)
else:
posts=Post.objects.all()
return render(request,posts.html,{'posts':posts})
Now what I want is that if there is nothing passed as sort in the url or the url is like : /posts/ I want to display all posts but if the parameter is 'time' then I want to order_by as in my view. But currently if nothing is passed in url for sort then I get the error that no path found the url.
str converter is defined as follows:
class StringConverter:
regex = '[^/]+'
# other methods
Which means it requires at least one character (note +, not *). You can create a new url mapping and manually pass empty string as sort parameter:
path('posts/', views.posts, kwargs={'sort': ''})
You can also register your own converter to allow empty string or just switch to plain old re_path. These options are preferred in case if you want to reduce code repetition and reuse this behavior somewhere else. They also allow you to keep the same url name (useful if you're planning to reverse urls)
Related
I have some code and when it executes, it throws a NoReverseMatch, saying:
NoReverseMatch at /my_url/ Reverse for 'my_url_name' with arguments '()' and keyword arguments '{}' not found. n pattern(s) tried: []
What does this mean, and what can I do about it?
The NoReverseMatch error is saying that Django cannot find a matching url pattern for the url you've provided in any of your installed app's urls.
The NoReverseMatch exception is raised by django.core.urlresolvers when a matching URL in your URLconf cannot be identified based on the parameters supplied.
To start debugging it, you need to start by disecting the error message given to you.
NoReverseMatch at /my_url/
This is the url that is currently being rendered, it is this url that your application is currently trying to access but it contains a url that cannot be matched
Reverse for 'my_url_name'
This is the name of the url that it cannot find
with arguments '()' and
These are the non-keyword arguments its providing to the url
keyword arguments '{}' not found.
These are the keyword arguments its providing to the url
n pattern(s) tried: []
These are the patterns that it was able to find in your urls.py files that it tried to match against
Start by locating the code in your source relevant to the url that is currently being rendered - the url, the view, and any templates involved. In most cases, this will be the part of the code you're currently developing.
Once you've done this, read through the code in the order that django would be following until you reach the line of code that is trying to construct a url for your my_url_name. Again, this is probably in a place you've recently changed.
Now that you've discovered where the error is occuring, use the other parts of the error message to work out the issue.
The url name
Are there any typos?
Have you provided the url you're trying to access the given name?
If you have set app_name in the app's urls.py (e.g. app_name = 'my_app') or if you included the app with a namespace (e.g. include('myapp.urls', namespace='myapp'), then you need to include the namespace when reversing, e.g. {% url 'myapp:my_url_name' %} or reverse('myapp:my_url_name').
Arguments and Keyword Arguments
The arguments and keyword arguments are used to match against any capture groups that are present within the given url which can be identified by the surrounding () brackets in the url pattern.
Assuming the url you're matching requires additional arguments, take a look in the error message and first take a look if the value for the given arguments look to be correct.
If they aren't correct:
The value is missing or an empty string
This generally means that the value you're passing in doesn't contain the value you expect it to be. Take a look where you assign the value for it, set breakpoints, and you'll need to figure out why this value doesn't get passed through correctly.
The keyword argument has a typo
Correct this either in the url pattern, or in the url you're constructing.
If they are correct:
Debug the regex
You can use a website such as regexr to quickly test whether your pattern matches the url you think you're creating, Copy the url pattern into the regex field at the top, and then use the text area to include any urls that you think it should match against.
Common Mistakes:
Matching against the . wild card character or any other regex characters
Remember to escape the specific characters with a \ prefix
Only matching against lower/upper case characters
Try using either a-Z or \w instead of a-z or A-Z
Check that pattern you're matching is included within the patterns tried
If it isn't here then its possible that you have forgotten to include your app within the INSTALLED_APPS setting (or the ordering of the apps within INSTALLED_APPS may need looking at)
Django Version
In Django 1.10, the ability to reverse a url by its python path was removed. The named path should be used instead.
If you're still unable to track down the problem, then feel free to ask a new question that includes what you've tried, what you've researched (You can link to this question), and then include the relevant code to the issue - the url that you're matching, any relevant url patterns, the part of the error message that shows what django tried to match, and possibly the INSTALLED_APPS setting if applicable.
A very common error is when you get with arguments ('',). This is caused by something like this:
{% url 'view-name' does_not_exist %}
As does_not_exist doesn't exist, django evaluates it to the empty string, causing this error message.
If you install django-fastdev you will instead get a nice crash saying does_not_exist doesn't exist which is the real problem.
With django-extensions you can make sure your route in the list of routes:
./manage.py show_urls | grep path_or_name
If the route is missing you probably have not imported the application.
It may be that it's not loading the template you expect. I added a new class that inherited from UpdateView - I thought it would automatically pick the template from what I named my class, but it actually loaded it based on the model property on the class, which resulted in another (wrong) template being loaded. Once I explicitly set template_name for the new class, it worked fine.
The arguments part is typically an object from your models. Remember to add it to your context in the view. Otherwise a reference to the object in the template will be empty and therefore not match a url with an object_id.
Watch out for different arguments passing between reverse() and redirect() for example:
url(r"^some_app/(?P<some_id>\d+)/$", some_view_function, name="some_view")
will work with:
reverse("some_view", kwargs={"some_id": my_id})
and:
redirect("some_view", some_id=my_id)
but not with:
reverse("some_view", some_id=my_id)
and:
redirect("some_view", kwargs={"some_id": my_id})
This is my current url path is as http://localhost:8000/api/projects/abcml/2021
and in the urls.py page I am passing as path("api/projects/<str:project_handle>/<int:year>", functionname...) and in the view, I accept this parameters with self.kwargs.get method.
I want to pass url as this format http://localhost:8000/api/projects/abcml/?year=2021
What changes do I need to make in url pattern?
I tried this path("api/projects/<str:project_handle>/?year=<int:year> but did not seem correct also in the view page, instead of self.kwargs.get I changed it to self.request.query_params.get for year parameter. That did not work either. Error it throwing is Page not found (404).
The query string [wiki] is not part of the path, and therefore can not be matched.
You thus specify as path:
path('api/projects/<str:project_handle>/', functionname)
In the view, you can access the data with self.request.GET['year'] and this will return a string or a KeyError in cas the year was not provided in the query string.
I'm new to Django and I'm developing a project in which there are profile pages.
Well, the problem is that the primary key has whitespaces but I don't want them to show in the url, neither like "%20%", I want to join the words. For example:
website.com/Example Studios --> website.com/examplestudios
I've tried this:
url ( (r'^(?P<studio_name>[\w ]+)/$').replace(" ", ""), views.StudioView, name = 'dev_profile')
But didn't work (it seems like it turns the raw part to string before reading the url) and with 're' happens the same. I've been searching for solutions but I'm not able to find them (and slugify doesn't convinces me).
What's solution to this or what do you recommend?
In urls you define patterens which Django will catch e.g. r'^test/$' this means that when someone try to get yourdomain.com/test Django will catch it and call the view which will probably render template. You need to solve your problem on url generation e.g. in template . Therefore in urls:
url ( (r'^(?P<studio_name>[\w ]+)/$'), views.StudioView, name = 'dev_profile').
You need to transform primary key to word without space in template. One way is to use slug for every record.
Also add slug field to Studio model which is autogenerated and non-editable field(you can generate it from name e.g. Example Studios->examplestudios).
I need to support following urls in single url regex.
/hotel_lists/view/
/photo_lists/view/
/review_lists/view/
how to support all above urls in single views?
I tried something like below
url(r'^\_lists$/(?P<resource>.*)/$', 'admin.views.customlist_handler'),
edit:
hotel,photo, review is just example. that first part will be dynamic. first part can be anything.
If you wish to capture the resource type in the view, you could do this:
url(r'^(?P<resource>hotel|photo|review)_lists/view/$', 'admin.views.customlist_handler'),
Or to make it more generic,
url(r'^(?P<resource>[a-z]+)_lists/view/$', 'admin.views.customlist_handler'), #Or whatever regex pattern is more appropriate
and in the view
def customlist_handler(request, resource):
#You have access to the resource type specified in the URL.
...
You can read more on named URL pattern groups here
Given:
urlpatterns = \
patterns('blog.views',
(r'^blog/(?P<year>\d{4})/$', 'year_archive', {'foo': 'bar'}),
)
in a urls.py file. (Should it be 'archive_year' instead
of 'year_archive' ? - see below for ref.)
Is it possible to capture information from the URL
matching (the value of "year" in this case) for use in
the optional dictionary?. E.g.: the value of year
instead 'bar'?
Replacing 'bar' with year results in: "NameError ...
name 'year' is not defined".
The above is just an example; I know that year is
available in the template HTML file for archive_year,
but this is not the case for archive_month. And there
could be custom information represented in the URL that
is needed in a template HTML file.
(The example is from page "URL dispatcher", section "Passing
extra options to view functions",
http://docs.djangoproject.com/en/dev/topics/http/urls/,
in the Django documentation.)
No, that's not possible within the URLConf -- the dispatcher has a fixed set of things it does. (It takes the group dictionary from your regex match and passes it as keyword arguments to your view function.) Within your (custom) view function, you should be able to manipulate how those values are passed into the template context.
Writing a custom view to map year to "foo" given this URLConf would be something like:
def custom_view(request, year, foo):
context = RequestContext(request, {'foo': year})
return render_to_response('my_template.tmpl', context)
The reason that you get a NameError in the case you're describing is because Python is looking for an identifier called year in the surrounding scope and it doesn't exist there -- it's only a substring in the regex pattern.