Building your MVP with Django: Lessons Learned Building and Launching a SaaS

A presentation given at DjangoCongress 2018 discussing lessons learned when building kwoosh.com with Django. Includes methods and techniques for helping you improve the maintainability of your Django service.

Transcript

1. Building your MVP with Django Lessons Learned Building and Launching a SaaS @jamesvandyne
2. Agenda 1. Introduction 2. What is a SaaS / MVP? 3. Django Backend Lessons 4. Django Frontend Lessons 5. Q&A
3. James Van Dyne ϰΝϯμΠϯɾδΣʔϜε @jamesvandyne BeProud, Inc.
4. Why should you listen to me?
5. Why should you listen to me? 4 Been working with Django since around 1.0-ish 4 Worked on some of the largest Django sites in the US
6. 4 Full Remote OK 4 7.5 Hour Standard Work Day 4 Great co-workers 4 Work-life balance
7. Slack Reminders
8. Python Professional Programming 3 Coming soon
9. work with me beproud.jp/careers/en/
10. Goals 4 Avoid the same mistakes I made 4 Help you make your code base more maintainable 4 Share some techniques that work well for me
11. Software As A Service Minimum Viable Product
12. What is an MVP
13. image: anoda.mobi
14. image: anoda.mobi
15. What is your MVP? It depends
16. Project Management for Software Teams kwoosh.com
18. Django has batteries (use them)
19. Proper implementations are still a lot of work
20. User
21. What NOT to do
22. # models.py class UserProfile(models.Model): user = models.OneToOneField(User) accounts = models.ManyToManyField(CompanyAccount) title = models.CharField(max_length=32, blank=True, null=True) TZ_CHOICES = [(tz, tz) for tz in common_timezones] timezone = models.CharField(max_length=30, default='UTC', choices=TZ_CHOICES)
23. # monkey_patches.py from django.contrib.auth.models import User from company_accounts.models import UserProfile def user_profile(self): return UserProfile.objects.get(pk=self.pk) User.profile = user_profile
24. # apps.py class CompanyAccountConfig(AppConfig): name = 'company_accounts' def ready(self): import company_accounts.monkey_patches
25. A better way from django.contrib.auth.models import AbstractBaseUser class User(AbstractBaseUser): email = models.EmailField(_('email address'), max_length=254, unique=True) first_name = models.CharField(_('first name'), max_length=30, blank=True) last_name = models.CharField(_('last name'), max_length=30, blank=True) is_confirmed = models.BooleanField(default=False) title = models.CharField(max_length=32, blank=True, null=True) timezone = models.CharField(max_length=30, default='UTC', choices=TZ_CHOICES) USERNAME_FIELD = 'email' class Meta: db_table = 'users'
26. ManyToManyField
27. 4 2 Examples: 1. User Account Access 2. Task Assignees
28. User Account Access
29. Before class UserProfile(models.Model): user = models.OneToOneField(User) accounts = models.ManyToManyField(CompanyAccount)
30. After from django.contrib.auth import get_user_model from accounts.models import Account class AccountAccess(StatusMixin, models.Model): account = models.ForeignKey(Account) user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, related_name='user_%(class)s') class Meta: unique_together = ('user', 'account',) db_table = 'account_access'
31. class StatusMixin(BaseMixin): ACTIVE = 1 INACTIVE = 0 DELETED = -1 STATUS_CHOICES = ( (ACTIVE, _('Active')), (INACTIVE, _('Inactive')), (DELETED, _('Deleted')), ) status = models.IntegerField(choices=STATUS_CHOICES, default=ACTIVE) objects = StatusMixinManager() all_objects = models.Manager() class Meta: abstract = True
32. Task Assignees
33. Before class Task(ItemData): cache_key = "task_" _clearing = False _assignees_on_create = None assigned_to = models.ManyToManyField('auth.User', blank=True, related_name='related_name') state = models.IntegerField(choices=STATE_CHOICES, default=TODO) is_priority = models.BooleanField(default=False) class Meta: verbose_name_plural = "Tasks"
34. After # models.py class Task(StatusMixin, models.Model): assigned_to = models.ManyToManyField(get_user_model(), through='AssignedTo', through_fields=( 'task', 'user')) class AssignedTo(models.Model): user = models.ForeignKey(get_user_model(), on_delete=models.CASCADE, related_name='user_%(class)s') task = models.ForeignKey('tasks.Task', on_delete=models.CASCADE, related_name='task_%(class)s')
35. Class Based Views
36. What are Class Based Views? #views.py from django.views.generic.detail import DetailView class UserProfileView(DetailView): model = User # urls.py urlpatterns = [ url(r'^(?P<pk>\d+)/$', UserProfileView.as_view(), name='user-profile'), ]
37. The Promise 4 Write simpler, shorter code 4 Reuse existing components for quicker development 4 Easily mix in new functionality
38. Do Class Based Views Deliver?
39. It depends
40. Before class BasicProfileView(KwooshModelFormView, ProfilePageNav, AccountBasicFilterbar): form_class = KwooshProfileForm template_name = "users/profile_basic.html" page_template = "users/parts/basic.html" active_pagenav = "profile" active_filterbar = 'profile' page_id = "profile" def get_form(self, form_class=None): if form_class is None: form_class = self.form_class return form_class(self.request.POST or None, **self.get_form_kwargs()) def get_form_kwargs(self): self.object = get_object_or_404(User, pk=self.kwargs['pk']) if UserAccountAccess.objects.filter(user=self.object, account__pk__in=self.request.accounts).exists(): return { 'instance': self.object, 'request': self.request } else: raise exceptions.PermissionDenied
41. def get_context_data(self, **kwargs): if 'form' not in kwargs: kwargs['form'] = self.get_form() # context updating return context def form_invalid(self, form): context = self.get_context_data(form=form) return self.render_to_response(context) def form_valid(self, form): form.save() context = self.get_context_data(form=form) messages.success(self.request, "Saved Profile Successfully", extra_tags="local") return self.render_to_response(context)
42. After @authenticated @set_instance_object('users.models.User') def user(request, pk): # Show user def get(request, pk): form = EditUser(request=request, instance=request.instance) ... return response # Edit user @ensure_csrf_cookie @owns_instance_user def post(request, pk): # Create/Process the form return response return resolve_http_method({'get': get, 'post': post}, request, pk=pk)
43. Templates
44. Server Side Rendering 4 Simple and well documented 4 I can spend more time in Python (!)
45. Don't Repeat Yourself <!-- tasks.html--> <ul> {% for task in tasks %} {% include "task_item.html" } {% endfor %} </ul> <!-- tasks_item.html--> <li> <div class="task"> {{ task.title }} {% for assignee in task.assignees %} {% include "user_icon.html" %} {% endfor %} </div> </li>
47. Template Issues 4 Unexpected database calls 4 Cache invalidation
48. Too slow for complex apps
49. Include {% for x in loops %} {% include "inner.html" } {% endfor %} <!-- inner.html--> <h1>Hello, {{x}}</h1>
50. Inline {% for x in loops %} <h1>Hello, {{x}}</h1> {% endfor %}
51. Results run include inline 1 0.09034180641174316 0.030562877655029297 2 0.08458805084228516 0.032724857330322266 3 0.08182239532470703 0.03140902519226074 4 0.08819007873535156 0.03286027908325195 Avg 86.24ms Avg: 31.89
52. 270% faster
53. !
54. After
55. Take Aways
56. 1. Build Less Build Better
57. 2. Think through your models
58. 3. Avoid Class Based Views
59. 4. Consider Rendering in the Client
60. 5. Sometimes ! is the right solution
61. Thank you kwoosh.com