---
tags: Django, hack
---

# Django Dynamic URLs

Have you ever considered to create dynamic urls in Django?
Not the url parameters but the ones which are gernerated according to data from a database or a file.

## Concepts

Normally, we create an url path in `urls.py` and map each url to a view function or class:

path('demo', app.demo, related_name="demo")
path('demo_class', app.DemoClass.as_view(), related_name="demo_class")

The path function needs a url string, a view function and other parameters.

The point is how do we make the url string and the view function dynamic?

## Dynamic Import

The module `imorptlib` offers you to import module by moudle's name.

module = importlib.import_module('sys')
# <module 'sys' (built-in)>

As you can see, the module's name is a string, that means we have more flexibilty to get the modules we want.

Import the views through this method would be like:

view_module = importlib.import_module('%s.views' % app_name)

## Get The View

Next step, we need to get the view from the view_module.
A view is an attribute of the view_module, you can see the attribute listed by built-in function `dir()`.

dir(view_module)

We use the built-in function `getattr()` to get the view.

view = getattr(view_module, 'myView')

## Class Based View or Function Based View

We have to decide the view is a CBV or a FBV. The biggest difference between these two types of view is, CBV needs to call out `as_view()` function.

It means we have to find out wether the class is a class or not:

view_function = view.as_view() if inspect.isclass(view) else view

## Return

For the case of Django build-in path method `include`:

include('app.urls')

#(<module 'app.urls' from 'E:\\myproject\\app\\urls.py'>, None, None)

Last two parameters are **app_name** and **namesapce**.
That means we should add these two parameters when returning the patterns.

All in all,

def dynamic_urls(programs):
    urlpatters = []

    for program in programs:
        module_name, view_name = program
        url = '%s/%s' % (module_name, view_name)
        # depends on the rule you use
        module = importlib.import_module('%s.views' % module_name)
        # dynamic import
        view = getattr(module, view_name, None)
        if view:
            view = view.as_view() if inspect.isclass(view) else view
            urlpatterns.append(
                path(url, view)
            )
    return urlpatterns, None, None

dynamic_urls(programs)

# ([<URLPattern 'app/viewa'>, <URLPattern 'app/viewb'>,
#   <URLPattern 'common/viewc'>, None, None)

Then you can do something like this in your upper level urls.py:

programs = (
    ('app', 'viewa'),
    ('app', 'viewb'),
    ('common', 'viewc'),
)


path('demo/', dynamic_urls(programs))

As you see, you can let programs comes from database or other data srouces.

;-)