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(validate = [email_validator])](https://image.slidesharecdn.com/phillypug-djangomodels-150918192447-lva1-app6892/85/An-Overview-of-Models-in-Django-21-320.jpg)
![models.py
from django.db import models
from django.core.exceptions import ValidationError
def validate_embed(value):
valid_embed = (checks embed at vimeo.com)
if not valid_embed:
raise ValidationError(‘That embed code does not
exist at vimeo.com’)
class Video(models.Model):
embed = integerField(validators = [validate_embed])](https://image.slidesharecdn.com/phillypug-djangomodels-150918192447-lva1-app6892/85/An-Overview-of-Models-in-Django-22-320.jpg)
![Validators
(validate = [email_validator])](https://image.slidesharecdn.com/phillypug-djangomodels-150918192447-lva1-app6892/75/An-Overview-of-Models-in-Django-21-2048.jpg)
![models.py
from django.db import models
from django.core.exceptions import ValidationError
def validate_embed(value):
valid_embed = (checks embed at vimeo.com)
if not valid_embed:
raise ValidationError(‘That embed code does not
exist at vimeo.com’)
class Video(models.Model):
embed = integerField(validators = [validate_embed])](https://image.slidesharecdn.com/phillypug-djangomodels-150918192447-lva1-app6892/75/An-Overview-of-Models-in-Django-22-2048.jpg)
Uploaded byMichael Auritt
An Overview of Models in Django
The document provides an overview of Django models, which are used to manage data within a web application. It explains the structure of models, including field definitions and relationships such as many-to-one and many-to-many. Additionally, it covers querying data through Django's ORM and practical examples of model methods and validation techniques.
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An Overview of Models in Django
- 1. An Overview ofModels in Django
- 2. Michael Auritt • Directorof Media Production at CorpU • Self-taught programmer • Twitter: @mauritt
- 3.
- 4. Django • Models • Views •Templates
- 5. Django • Models -Manage our data • Views - Query the data • Template - Present the data
- 6. Django • Models -Manage our data • Views - Query the data • Template - Present the data
- 7. Models • The singledefinitive source of information about your website data • Uses Django’s Object-relational Mapper • Each model maps to a single database table • Each field maps to a column within that table
- 8. Talent Management TheHappiness Advantage CorpU Promo My Video Portfolio Videos | About | Contact Supply Chain Management http://www.myvideoportfolio.com/videos
- 9. Supply Chain Management MyVideo Portfolio Videos| About | Contact http://www.djangodjunction.com/djangos/01 This course explores end-to-end supply chain management. This video takes a look at the main elements of a modern supply chain and…
- 10. Supply Chain Management MyVideo Portfolio Videos| About | Contact http://www.djangodjunction.com/djangos/01 TITLE DESCRIPTION Embed This course explores end-to-end supply chain management. This video takes a look at the main elements of a modern supply chain and…
- 11. models.py from django.db importmodels class Video(models.Model): title = models.CharField(max_length = 200) description = models.TextField() embed_key = models.IntegerField() date_completed = models.DateField()
- 12. id(primary key) title description embed_keydate_completed Video
- 13. id title descriptionembed_key date_completed 1 Ursa Motors In this video… 679210 2014-10-01 2 Sea Box Sea Box is a company that… 933750 2015-03-15 3 Critical Thinking In Critical Thinking… 876025 2014-09-23 4 CorpU Promo CorpU’s platform… 867302 2015-02-05 video
- 14. models.py from django.db importmodels class Video(models.Model): title = models.CharField(max_length = 200) description = models.TextField() embed_key = models.IntegerField() date_completed = models.DateField()
- 15.
- 16. models.py from django.db importmodels class Video(models.Model): title = models.CharField(max_length = 200) description = models.TextField() embed_key = models.IntegerField() date_completed = models.DateField()
- 17.
- 18.
- 19.
- 20. Validators • validate_slug • EmailValidator •URLValidator
- 21.
- 22. models.py from django.db importmodels from django.core.exceptions import ValidationError def validate_embed(value): valid_embed = (checks embed at vimeo.com) if not valid_embed: raise ValidationError(‘That embed code does not exist at vimeo.com’) class Video(models.Model): embed = integerField(validators = [validate_embed])
- 23. Field Choices GENRE_CHOICES =( (‘DOC’, ‘Documentary’ ), (‘PRO’, ‘Promo’), (‘NAR’,’Narrative’), ) genre = models.CharField( max_length = 3, choices = GENRE_CHOICES )
- 24. models.py from django.db importmodels class Video(models.Model): title = models.CharField(max_length = 200) description = models.TextField() embed_key = models.IntegerField() date_completed = models.DateField() hidden = models.BooleanField(default = True) slug = models.SlugField(unique = True)
- 25. Relationships • Many toOne • Many to Many • One to One
- 26. Many to One Onerow of a database table relates to many rows of another.
- 27. title … client …Client: 01 … Client: 02 … Client: 01 … Client: 03 … Client: 01 … Client: 02 id name website … 01 … … 02 … … 03 … Video Client Many to One
- 28. Many to One classClient(models.Model): name = models.CharField(unique = True) website = models.URLField() class Video(models.Model): client = models.ForeignKey(Client)
- 29. Many to Many Manyrows of a database table relate to many rows of another.
- 30. … role … role: CameraOp, Editor, Producer … role: Camera Op, Editor … role: Producer … role: Editor name … Camera Op … Editor … Producer … Video Role Many to Many
- 31. Many to Many classRole(models.Model): name = models.CharField(unique = True) class Video(models.Model): role = models.ManyToManyField(Role)
- 32. One to One Onerow of a database table relates to one row of another.
- 33. … file … File:1 … File: 2 … File 3 … FIle 4 Video One to One id path 1 2 3 4 File
- 34. One to One classFile(models.Model): drive = models.CharField() path = models.FilePathField() class Video(models.Model): file = models.OneToOneField(File)
- 35. $ python manage.pymakemigrations
- 36. Migrations operations = [ migrations.CreateModel( name='Video', fields=[ ('id',models.AutoField(serialize=False, primary_key=True, auto_created=True, verbose_name='ID')), ('title', models.CharField(max_length=200)), ('description', models.TextField()), ('embed', models.TextField()), ('company', models.ForeignKey(to='videos.Company')), ('roles', models.ManyToManyField(to='videos.Role')),
- 37. $ python manage.pymigrate
- 38.
- 39. Migration Issues • Addingnew fields without a default • Adding new unique fields • Changing relationships
- 40. Queries Returning Many Objects •Video.objects.all() • Video.obects.filter(client = ‘MasterCard’) • Video.objects.all().order_by(‘date_created’)
- 41. Queries Returning Many Objects MC_Videos= Video.obects.filter(client = ‘MasterCard’) MC_Ascending_Order = MC_videos.order_by(‘title’) MC_Descending_Order = MC_videos.order_by(‘-title’)
- 42. Queries Returning Many Objects MC_videos= Video.obects.filter(client = ‘MasterCard’) MC_videos = MC_videos.order_by(‘date_created’) MC_videos = MC_videos.exclude(Role = ‘Producer’)
- 43.
- 44. Queries Returning Single Objects •Video.objects.get(pk = 1) • Video.objects.get(title = ‘My Best Video’)
- 45. Queries • QuerySet APIReference in Django Docs • QuerySets are lazy • QuerySets are faster than using Python
- 46. Queries >>>from video.models importVideo >>> v = Video.objects.get(pk = 1) >>> print(v) <Video: Video object>
- 47. Model Methods from django.dbimport models class Video(models.Model): title = models.CharField(max_length = 200) def __str__(self): return self.title
- 48. Queries >>>from video.models importVideo >>> v = Video.objects.get(pk = 1) >>> print(v) <Video: Talent Management>
- 49. Model Methods class Role(models.Model): name= models.CharField(unique = True) class Video(models.Model): def is_full_stack(self): full_stack = True for role in Role.objects.all(): if role not in self.role.all(): full_stack = False return full_stack
- 50. Model Methods >>>from video.modelsimport Video >>> v = Video.get(pk = 1) >>> v.is_full_stack() True
- 51. Views.py def detail(request, slug): try: video= Video.Objects.get(slug = slug) except video.DoesNotExist: raise Http404() else: context = {‘video’: video} return render(request, ‘videos/detail.html’, context)
- 52.
- 53.
- 54. Thanks Further Reading • djangoproject.com •Two Scoops of Django (TwoScoopsPress.com) • Lightweight Django (O’Reilly)
Editor's Notes
- #3 Not from a programming background Give Talk to learn more about Django You should give a talk
- #4 We’re here tonight to talk about Django Models I know a lot of you are learning Python Polls tutorial db —> models —> view —> template —> html
- #8 Models are python objects To understand that, let’s think of a finished website I work in video
- #9 List view of videos
- #12 a subclass of Django’s model object in that model is contained a set of fields each field type accepts a different type of data
- #13 id field primary key
- #15 List of fields is not exhaustive
- #17 Looking good
- #20 How does Django make sure slugs are formatted correctly? Built in validators
- #22 passed in as list contradictory validators
- #40 If we add a new field to an already populated DB table Django is going to want to fill in that field for each row that exists
- #46 So we have all of our queries set, but there’s a problem