[Answered ]-Changing API Versioning Strategy

Versioning is very simple.

Create folder in your app and name it to v1

Like this image:

yourApp > urls.py should be like this:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('v1/', include('api.v1.urls')),
]

Then create urls.py in v1 folder, it should something like this:

from django.urls import path, include
from api.v1.classes.Plan import listPlan
from api.v1.classes.preInvoce import preInvoce    

urlpatterns = [
    path('plan/list', listPlan.as_view(), name="listPlans"),
    path('plan/buy', preInvoce.as_view(), name="preInvoice"),
]

If you want have version 2 you need to create new folder called v2 and have urls.py in it.

and your app urls.py should be like this:

from django.contrib import admin
from django.urls import path, include

urlpatterns = [
    path('v1/', include('api.v1.urls')),
    path('v2/', include('api.v2.urls')),
]

Put your own and new urls in v2/urls.py

Your final v1 urls like this:

localhost:8000/v1/planList

Your final v2 urls like this:

localhost:8000/v2/newUrlInV2

Both v1 and v2 urls should works correctly.