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This is my url:

url(r'^add/(?P<year>[0-9]+)/(?P<month>[0-9]+)/(?P<day>[0-9]+)/(?P<id>[0-9]*)$', views.AddWorkoutView.as_view(), name = 'add_workout'),

It is for adding workouts to the database. If the id is provided, the server should:

  1. Check if a workout with the id exists in database
  2. If it exists, destroy the found item and replace it with the one who's data has been posted to the view.
  3. If it doesn't exist, simply add the new workout to the database without destroying any existing workout object.

In one of my templates, called addworkout.html, I have a form where the workout data is inserted. It has the following opening tag:

<form id="workoutform" action="{% url 'workoutcal:add_workout' date.year date.month date.day %}" method="post">

As you can see, I haven't provided any id argument in the reverse url. This is because in addworkout.html the user can only add new workouts, so no existing workout id is necessary. However, this attempt at reversing the url generates an error:

NoReverseMatch at /workoutcal/add/2018/1/2/
Reverse for 'add_workout' with arguments '(2018, 1, 2)' not found. 1 pattern(s) tried: ['workoutcal/add/(?P<year>[0-9]+)/(?P<month>[0-9]+)/(?P<day>[0-9]+)/(?P<id>[0-9]*)$']

Since I have written a regex star next to the id number in the url, there shouldn't be any requirement to provide id. The only explanation I can think of is that the last forward slash is the culprit, maybe it isn't generated when reversing the url.

If my explanation is correct, how do I deal with this trailing slash problem the best way?

Sahand
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    Try making that `/`+digits optional: `r'^add/(?P[0-9]+)/(?P[0-9]+)/(?P[0-9]+)(?:/(?P[0-9]*))?$'`, replace `/(?P[0-9]*)` with `(?:/(?P[0-9]*))?`. Or maybe in this case, make the digits obligatory by replacing `*` with `+`. – Wiktor Stribiżew Jan 10 '18 at 12:52
  • Good idea. Should I change the * to a + also? – Sahand Jan 10 '18 at 12:53
  • If there must be at least 1 digit after that slash, yes. I edited the comment above. – Wiktor Stribiżew Jan 10 '18 at 12:54
  • It's best not to make it a + because the browser tends to add a `/` after the url. – Sahand Jan 10 '18 at 12:54
  • Note that using `*` doesnt make it optional, it just means that it will match `''`. The `url` tag fails to reverse because the URL pattern requires 4 arguments (the fourth can be `''`) but you only provide 3. – Alasdair Jan 10 '18 at 13:01

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