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})
Related
This question already has an answer here:
How to pass arguments with slash in Django2 urls
(1 answer)
Closed 6 months ago.
I'm writing a project with python 3.10 and django 4.1
I defined the following route:
app_name = 'admin_extend'
urlpatterns = [
path('add_fav/<str:name>/<str:add_url>/<str:admin_url>/', views.add_fav, name='add_fav'),
]
now i have 3 parameters here, name, add_url and admin_url.
both add_url and admin_url contains '/' so i need to be able to escape them in the django template.
this is my code in the template:
{% translate 'Fav' %}
lets say the parameters value are name='foo', add_url='/a/b/c/', admin_url='/c/d/e/',
the route fails with NoReverseMatch:
Reverse for 'add_fav' with keyword arguments '{'name': 'foo', 'add_url': '/a/b/c/', 'admin_url': '/c/d/e/'}' not found. 1 pattern(s) tried: ['admin_extend/add_fav/(?P<name>[^/]+)/(?P<add_url>[^/]+)/(?P<admin_url>[^/]+)/\\Z']
i tested it and if i provide the parameters without / characters then i get no error.
my problem is i really can't find anywhere how to escape these parameters, i googled and checked on stackoverflow a lot
for example i can't use the {% filter urlencode %} before and after because the url needs to be validated first and then it will go through the urlencode,
i learned that i can't run python code in these templates so i can't use urlqoute from django.utils.http
and using urlencode filter in this way is not a correct syntax:
{% url 'admin_extend:add_fav' name=(model.name|urlencode) add_url=(model.add_url|urlencode) admin_url=(model.admin_url|urlencode) %}
how can I resolve this ?
thanks
thanks to #Amrez the solution was more simple than expected, the solution is at How to pass arguments with slash in Django2 urls
i defined the url argument types as str, and i didn't know there is a type called path exactly for this case, so just by changing the url pattern the issue was resolved and i didn't need to escape anything, but NOTICE this, original i add <path:add_url>/<path:admin_url> since path contains / in it, it confused the url parser and both parameters where entered to the add_url variable. i needed to change it to # instead of / and it works properly:
path('add_fav/<str:name>/<path:add_url>#<path:admin_url>/', views.add_fav, name='add_fav')
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})
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+)/$", some_view_function, name="some_view")
will work with:
reverse("some_view", kwargs={"some_id": my_id})
and:
redirect("some_view", some_id=my_id)
but not with:
reverse("some_view", some_id=my_id)
and:
redirect("some_view", kwargs={"some_id": my_id})
I followed the Django tutorial on how to use the url dispatcher, but for the life of me cannot figure out why I am getting this error.
Reverse for 'details' with arguments '('my_address',)' and keyword
arguments
'{}' not found. 1 pattern(s) tried: ['details(?P[0-9]+)/$']
My url.py:
url(r'^details(?P<zip>[0-9]+)/$', views.search_details, name='details'),
The url used in my template:
<h1>Data for {{data.zip}}</h1>
My view method declaration:
def search_details(request,zip):
When I try remove the parameter(zip) from the above code, the template renders, so I would believe the url is correct.
Your zip parameter matches digits from 0 to 9. The string "my_address" is not made up of those digits.
You should either pass a real zip, assuming those actually are numeric rather than alphabetic, or use a different pattern such as \w+.
I think your missing / after details:
url(r'^details/(?P<zip>[0-9]+)/$', views.search_details, name='details'),
I'm trying to match two strings in an url, but it's not working out likely due to my poor knowledge of regex. I want urls like the following:
testserver/username/
testserver/username/1234/
testserver/username/rewards/
Username would be passed in to the url as a kwarg. Here's what I have:
url(r'^(?P<username>[-\w]+)/$', Posts_Index, name="userposts"),
url(r'^(?P<username>[-\w]+)/photos/$', Photo_Index, name="userphotos"),
url(r'^(?P<username>[-\w]+)/rewards/$', Rewards_Index, name="userrewards"),
url(r'^(?P<username>[-\w]+)/following/$', Follower_Index, name="userfollowers"),
url(r'^(?P<username>[-\w]+)/followers/$', Following_Index, name="userfollowing"),
url(r'^(?P<username>[-\w]+)/(?P<pk>\d+)/$', SinglePost_Index, name="singlepost"),
However, only userposts will be found. If I try to query userphotos or anything below userposts, only the userposts url will be checked, which obviously leads to failure. How can I fix this issue?
From the django docs: Django runs through each URL pattern, in order, and stops at the first one that matches the requested URL.
Thus if you reverse the order of the urls it should work better.