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Building your MVP with Django
Lessons Learned Building and Launching a
SaaS
@jamesvandyne
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Agenda
1. Introduction
2. What is a SaaS / MVP?
3. Django Backend Lessons
4. Django Frontend Lessons
5. Q&A
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James Van Dyne
ϰΝϯμΠϯɾδΣʔϜε
@jamesvandyne
BeProud, Inc.
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Why should you listen to
me?
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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
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4 Full Remote OK
4 7.5 Hour Standard Work Day
4 Great co-workers
4 Work-life balance
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Slack Reminders
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Python Professional
Programming 3
Coming soon
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work with me
beproud.jp/careers/en/
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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
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Software As A Service
Minimum Viable Product
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What is an MVP
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image: anoda.mobi
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image: anoda.mobi
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What is your MVP?
It depends
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Project Management for Software Teams
kwoosh.com
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No content
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Django has batteries
(use them)
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Proper implementations are
still a lot of work
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User
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What NOT to do
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# 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)
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# 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
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# apps.py
class CompanyAccountConfig(AppConfig):
name = 'company_accounts'
def ready(self):
import company_accounts.monkey_patches
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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'
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ManyToManyField
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4 2 Examples:
1. User Account Access
2. Task Assignees
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User Account Access
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Before
class UserProfile(models.Model):
user = models.OneToOneField(User)
accounts = models.ManyToManyField(CompanyAccount)
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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'
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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
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Task Assignees
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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"
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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')
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Class Based Views
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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\d+)/$', UserProfileView.as_view(), name='user-profile'),
]
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The Promise
4 Write simpler, shorter code
4 Reuse existing components for quicker development
4 Easily mix in new functionality
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Do Class Based Views
Deliver?
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It depends
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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
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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)
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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)
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Templates
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Server Side Rendering
4 Simple and well documented
4 I can spend more time in Python (!)
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Don't Repeat Yourself
-
{% for task in tasks %}
{% include "task_item.html" }
{% endfor %}
{{ task.title }}
{% for assignee in task.assignees %}
{% include "user_icon.html" %}
{% endfor %}
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No content
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Template Issues
4 Unexpected database calls
4 Cache invalidation
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Too slow for complex apps
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Include
{% for x in loops %}
{% include "inner.html" }
{% endfor %}
Hello, {{x}}
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Inline
{% for x in loops %}
Hello, {{x}}
{% endfor %}Slide 51
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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
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270% faster
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!
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After
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Take Aways
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1. Build Less
Build Better
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2. Think through your
models
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3. Avoid Class Based Views
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4. Consider Rendering in
the Client
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5. Sometimes ! is the
right solution
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Thank you
kwoosh.com