django-service-objects

Service objects for Django

What?

This is a small library providing a Service base class to derive your service objects from. What are service objects? You can read more about the whys and hows in this blog post, but for the most part, it encapsulates your business logic, decoupling it from your views and model methods. Put your business logic in service objects.

Installation guide

Install from pypi:

pip install django-service-objects

Add service_objects to your INSTALLED_APPS:

# settings.py

INSTALLED_APPS = (
    ...
    'service_objects',
    ...
)

Example

Let's say you want to register new users. You could make a CreateUser service.

from django import forms

from service_objects.services import Service

class CreateUser(Service):
    email = forms.EmailField()
    password = forms.CharField(max_length=255)
    subscribe_to_newsletter = forms.BooleanField(required=False)

    def process(self):
        email = self.cleaned_data['email']
        password = self.cleaned_data['password']
        subscribe_to_newsletter = self.cleaned_data['subscribe_to_newsletter']

        self.user = User.objects.create_user(username=email, email=email, password=password)
        self.subscribe_to_newsletter = subscribe_to_newsletter

        if self.subscribe_to_newsletter:
            newsletter = Newsletter.objects.get()
            newsletter.subscribers.add(self.user)
            newsletter.save()
            
        return self.user
    
    def post_process(self):
        WelcomeEmail.send(self.user, is_subscribed=self.subsribe_to_newsletter)
        
        # Calling a celery task after successfully creating the user.
        create_billing_account.delay(self.user.id)

Notice that it's basically a Django form but with a process method. This method gets called when you call execute() on the process. If your inputs are invalid, it raises InvalidInputsError.

The newly added post_process can also be included for running extra tasks that need to be executed after the service completes.

Here's how you use it:

CreateUser.execute({
    'email': '[email protected]',
    'password': 'doorsofstone',
    'subscribe_to_newsletter': True,
})

Now you can use it anywhere.

In your views

# views.py

# Function Based View
def create_user_view(request):
    form = NewUserForm()
    if request.method == 'POST':
        form = NewUserForm(request.POST)

        if form.is_valid():
            try:
                CreateUser.execute(request.POST)
                return redirect('/success/')
            except Exception:
                form.add_error(None, 'Something went wrong')

    return render(request, 'registration/new-user.html', {'form': form})


# Class Based View
class CreateUserView(ServiceView):
    form_class = NewUserForm
    service_class = CreateUser
    template_name = 'registration/new-user.html'
    success_url = '/success/'

A management command

# management/commands/create_user.py

class Command(BaseCommand):
    help = "Creates a new user"

    def add_arguments(self, parser):
        parser.add_argument('email')
        parser.add_argument('password')

    def handle(self, *args, **options):
        user = CreateUser.execute(options)
        self.stdout.write(f'New user created : {user.email}')

In your tests

class CreateUserTest(TestCase):

    def test_create_user(self):
        inputs = {
            'email': '[email protected]',
            'password': 'do0r$0f$stone42',
            'subscribe_to_newsletter': True,
        }

        CreateUser.execute(inputs)

        user = User.objects.get()
        self.assertEqual(user.email, inputs['email'])

        newsletter = Newsletter.objects.get()
        self.assertIn(user, newsletter.subscribers.all())

And anywhere you want. You can even execute services inside other services. The possibilities are endless!

Documentation

Docs can be found on readthedocs.

If you have any questions about service objects, you can tweet me @mixxorz.