What is a NoReverseMatch error and how do I fix it

Question

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

User · Answer

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

User · Answer

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

User · Answer

And make sure your route in the list of routes     manage py show urls   grep path or name   https   github com django-extensions django-extensions

[django] What is a NoReverseMatch error, and how do I fix it?

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