Why do we need to pass in primary keys into our views and our urls? When do we generally need to pass in primary keys?

Question

Thank you advance for the help?

The motivation for my question is making sure I understand when to pass in primary keys.

Example in views.py

def step_detail(request, course_pk, step_pk):
    step = get_object_or_404(Step, course_id=course_pk, pk=step_pk)
    return render(request, 'courses/step_detail.html', {'step':step})

Example in step_detail.html

<a href="{% url 'courses:detail' pk=step.course.pk %}

Note 1) I get what primary keys are. They're like addresses. They are automatically generated ids. This was a good explanation imo https://www.essentialsql.com/what-is-the-difference-between-a-primary-key-and-a-foreign-key/

Note 2) I've looked through the following resources: https://teamtreehouse.com/community/whats-up-with-pks-django-course-views https://teamtreehouse.com/community/help-me-understand-ppk https://teamtreehouse.com/community/whats-the-correct-way-to-handle-bad-pks https://teamtreehouse.com/community/how-does-the-value-of-pk-the-named-regex-get-passed-to-viewscoursedetails

Answer 1 · 2017-03-24T15:12:20Z

March 24, 2017 3:12pm

If you're view is showing a specific piece of data, you should pass the primary key so your controller knows how to load that piece of data.

If you're view is showing a list of data (like a search view) then you're probably passing in search criteria, instead of a pk.

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Daniel Wu

Daniel Wu

Why do we need to pass in primary keys into our views and our urls? When do we generally need to pass in primary keys?

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Samuel Ferree

Samuel Ferree