-
-
Save aybruhm/f3bfd86e6f3036029d8386b8a26596ba to your computer and use it in GitHub Desktop.
Django models cheatsheet
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import uuid | |
from django.db import models | |
# Use the import below instead, if using GeoDjango fields | |
# from django.contrib.gis.db import models | |
from django.utils.translation import ugettext_lazy as _ | |
from django.contrib.postgres.fields import ( | |
ArrayField, | |
CICharField, | |
CIEmailField, | |
CITextField, | |
HStoreField, | |
IntegerRangeField, | |
BigIntegerRangeField, | |
DecimalRangeField, | |
DateTimeRangeField, | |
DateRangeField, | |
) | |
def file_directory_path(instance, filename): | |
# file will be uploaded to MEDIA_ROOT/my_files/{id}/{year}/{month}/{filename} | |
return f"my_files/{instance.id}/{timezone.now().date().strftime('%Y/%m')}/{filename}" | |
def create_rand_value(app_label, model_name, prefix=None, suffix_len=10): | |
""" | |
Just an example function, used to demonstrate overriding save() | |
It generates an easily readable, unique string | |
""" | |
code = "" | |
if prefix is not None: | |
code = code.join(prefix).join("-") | |
while True: | |
code = code.join(random.SystemRandom().choice("23456789BCDFGHJKMNPQRSTVWXYZ") for _ in range(suffix_len)) | |
Model = apps.get_model(app_label=app_label, model_name=model_name) | |
try: | |
present = Model.objects.first() | |
except Model.DoesNotExist: | |
present = None | |
if present is not None: | |
if not Model.objects.filter(code=code).exists(): | |
return code | |
# https://docs.djangoproject.com/en/3.1/topics/db/managers/#from-queryset | |
class MyModelQuerySet(models.QuerySet): | |
"""Used when we need to return a queryset that has been filtered in some way""" | |
def manager_and_queryset_method(self): | |
return | |
class MyModelManager(models.Manager): | |
"""Used when we need a table-level method that does NOT return a queryset""" | |
def manager_only_method(self): | |
return | |
CombinedMyModelManager = MyModelManager.from_queryset(MyModelQuerySet) | |
class MyModel(models.Model): | |
"""Comment""" | |
class CompanyType(models.TextChoices): | |
PUBLIC_LIMITED_COMPANY = 'PLC', _('Public Limited Company') | |
PRIVATE_COMPANY_LIMITED = 'LTD', _('Private Company limited by shares') | |
LIMITED_LIABILITY_PARTNERSHIP = 'LLP', _('Limited Liability Partnership') | |
__empty__ = _('(Unknown)') | |
# https://docs.djangoproject.com/en/3.1/ref/models/fields/ | |
boolean_field = models.BooleanField(_("Boolean"), default=False) | |
char_field = models.CharField(_("Character"), max_length=100, blank=True) | |
char_field_choice = models.CharField(_("Character Choices"), choices=CompanyType.choices, default=CompanyType.__empty__, max_length=100, blank=True) | |
date_field = models.DateField(_("Date"), null=True, blank=True) | |
datetime_field = models.DateTimeField(_("DateTime"), null=True, blank=True) | |
decimal_field = models.DecimalField(_("Decimal"), max_digits=5, decimal_places=2, null=True) | |
duration_field = models.DurationField(_("Duration"), ) | |
email_field = models.EmailField(_("Email"), max_length=254, blank=True) | |
file_field = models.FileField(_("File"), upload_to=file_directory_path, max_length=100) | |
float_field = models.FloatField(_("Float"), null=True) | |
generic_ip_address_field = models.GenericIPAddressField(_("Generic IP"), protocol='both', unpack_ipv4=False, null=True) # 'both', 'IPv4' or 'IPv6' | |
image_field = models.ImageField(_("Image"), upload_to=file_directory_path, height_field=None, width_field=None, max_length=100) | |
integer_field = models.IntegerField(_("Number"), null=True) | |
json_field = models.JSONField(_("JSONField"), default=dict) | |
pos_int_field = models.PositiveIntegerField(_("Positive Integer"), ) | |
pos_small_int_field = models.PositiveSmallIntegerField(_("Positive Small Integer"), ) | |
slug_field = models.SlugFiels(_("Slug"), max_length=50, blank=True) | |
small_int_field = models.SmallIntegerField(_("Small Integer"), ) | |
text_field = models.TextField(_("Text"), blank=True) | |
time_field = models.TimeField(_("Time"), null=True, blank=True) | |
url_field = models.URLField(_("URL"), max_length=200,) | |
uuid_field = models.UUIDField(_("UUID"), default=uuid.uuid4) | |
# Relationships | |
# https://docs.djangoproject.com/en/3.1/ref/models/fields/#module-django.db.models.fields.related | |
oto = models.OneToOneField(AA, on_delete=models.CASCADE, null=True, blank=True) | |
fk = models.ForeignKey(BB, on_delete=models.CASCADE, related_name="xxs", null=True, blank=True) | |
mtm = models.ManyToManyField(CC, blank=True) | |
# Auto-date fields | |
# https://docs.djangoproject.com/en/3.1/ref/models/fields/#datefield | |
created = models.DateTimeField(_("DateTime Created"), auto_now_add=True, help_text=_("When this item was created")) | |
modified = models.DateTimeField(_("DateTime Modified"), auto_now=True, help_text=_("When this item last updated")) | |
# Postgres-specific range fields | |
# https://docs.djangoproject.com/en/3.1/ref/contrib/postgres/fields/ | |
integer_range_field = IntegerRangeField(_("IntegerRange")) | |
big_integer_range_field = BigIntegerRangeField(_("BigIntegerRange")) | |
decimal_range_field = DecimalRangeField(_("DecimalRange")) | |
date_time_range_field = DateTimeRangeField(_("DateTimeRange")) | |
date_range_field = DateRangeField(_("DateRange")) | |
# GeoDjango fields | |
# https://docs.djangoproject.com/en/3.1/ref/contrib/gis/model-api/ | |
point = models.PointField(srid=4326) | |
multi_point = models.MultiPointField() | |
polygon = models.PolygonField() | |
multi_polygon = models.MultiPolygonField() | |
linestring = models.LineStringField() | |
multi_linestring = models.MultiLineStringField() | |
geometry_collection = models.GeometryCollectionField() | |
raster = models.RasterField() | |
objects = CombinedMyModelManager() | |
class Meta: | |
# https://docs.djangoproject.com/en/3.1/ref/models/options/ | |
verbose_name = _("My Model") | |
verbose_name_plural = _("My Models") | |
# abstract = True # https://docs.djangoproject.com/en/3.1/topics/db/models/#abstract-base-classes | |
# proxy = True # https://docs.djangoproject.com/en/3.1/topics/db/models/#proxy-models | |
db_table = 'my_model' | |
# Specifies the default field(s) to use in your model Manager’s latest() and earliest() methods. | |
get_latest_by = ['-datetime_field'] | |
# The default ordering for the object, for use when obtaining lists of objects: | |
ordering = ['-datetime_field'] | |
unique_together = [ | |
['char_field', 'slug_field'] | |
] | |
index_together = [ | |
["created", "char_field"], | |
] | |
# https://docs.djangoproject.com/en/3.1/ref/models/indexes/ | |
indexes = [ | |
models.Index(fields=['char_field', 'text_field']), | |
models.Index(fields=['url_field'], name='url_field_idx'), | |
] | |
# https://docs.djangoproject.com/en/3.1/ref/models/constraints/ | |
constraints = [ | |
models.CheckConstraint(check=models.Q(integer_field__gte=18), name='integer_gte_18'), | |
models.UniqueConstraint(fields=['created', 'slug_field'], name='unique_slug_created'), | |
models.UniqueConstraint( | |
fields=['fk'], | |
condition=Q(char_field_choice=CompanyType.LIMITED_LIABILITY_PARTNERSHIP), | |
name='unique_llc_for_fk' | |
), | |
] | |
def __str__(self): | |
# https://docs.djangoproject.com/en/3.1/ref/models/instances/#str | |
return f'{self.char_field} {self.char_field}' | |
def save(self, *args, **kwargs): | |
# https://docs.djangoproject.com/en/3.1/topics/db/models/#overriding-model-methods | |
if not self.pk: # this will ensure that the object is new | |
self.slug_field = create_rand_value( | |
app_label=self._meta.app_label, | |
model_name=self.__class__.__name__, | |
prefix="", | |
suffix_len=10 | |
) | |
super().save(*args, **kwargs) | |
def get_absolute_url(self): | |
# https://docs.djangoproject.com/en/3.1/ref/models/instances/#get-absolute-url | |
from django.urls import reverse | |
return reverse('people.views.details', args=[str(self.id)]) | |
@property | |
# https://docs.djangoproject.com/en/3.1/glossary/#term-property | |
def char_slug(self): | |
return self.char_field.lower().replace(' ','-') | |
def process_invoices(self): | |
do_something() |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment