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--- wiki2:python:django:models [2018/10/13 08:05]
alfred [Campos]
+++ wiki2:python:django:models [2020/05/09 09:25] (actual)
@@ Línea 1: / Línea 1: @@
 ====== Django Models ======
+===== Migrations =====
-===== Field configuration =====
+<code>
-==== Choice ====
+$ python manage.py makemigrations <app>
-<code python>
+</code>
-import calendar
+Will create migration files for all the apps if the ''app'' was not indicated.
-...
+<code>
+$ python manage.py migrate
+</code>
+Will apply migrations to the configured DB.
+===== Signals =====
-class MyModel(models.Model):
+==== Ways to connect signals ====
+<code python>
+class Award(models.Model):
+    name = models.CharField(max_length=200, unique=True)
     ...
-    MONTH_CHOICES = [(str(i), calendar.month_name[i]) for i in range(1,13)]
+    @classmethod
+    def pre_save(cls, sender, instance, **kwargs):
+        ...
-    month = CharField(max_length=9, choices=MONTHS_CHOICES, default='1')
+pre_save.connect(Award.pre_save, sender=Award)
 </code>
+<code python>
+from django.contrib.auth.models import User
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+class Profile(models.Model):
+    user = models.OneToOneField(User, on_delete=models.CASCADE)
+    bio = models.TextField(max_length=500, blank=True)
+    location = models.CharField(max_length=30, blank=True)
+    birth_date = models.DateField(null=True, blank=True)
+@receiver(post_save, sender=User)
+def create_user_profile(sender, instance, created, **kwargs):
+    if created:
+        Profile.objects.create(user=instance)
+@receiver(post_save, sender=User)
+def save_user_profile(sender, instance, **kwargs):
+    instance.profile.save()
+</code>
+===== Model configuration =====
 ==== Modelos proxy ====
 Proxy models are used to modify Python behaviour of a model by extending a model class. Database tables aren't generated for proxy models. So you can't use a proxy model for AUTH_USER_MODEL.
@@ Línea 36: / Línea 68: @@
     def award(self, user):
         # award a silver badge to user
+</code>
+===== Fields =====
+==== DateTime Field ====
+The auto_now_add will set the timezone.now() only when the instance is created, and auto_now will update the field everytime the save method is called.
+<code python>
+class Invoice(models.Model):
+    description = models.CharField(max_length=255)
+    status = models.CharField(max_length=10)
+    vendor = models.ForeignKey(Vendor)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
 </code>
 ==== Image Field ====
@@ Línea 65: / Línea 110: @@
 </code>
+==== Choice ====
+<code>
+from django.db import models
+class Person(models.Model):
+    SHIRT_SIZES = (
+        ('S', 'Small'),
+        ('M', 'Medium'),
+        ('L', 'Large'),
+    )
+    name = models.CharField(max_length=60)
+    shirt_size = models.CharField(max_length=2, choices=SHIRT_SIZES)
+</code>
+Get its values
+<code>
+>>> p = Person(name="Fred Flintstone", shirt_size="L")
+>>> p.save()
+>>> p.shirt_size
+'L'
+>>> p.get_shirt_size_display()
+'Large'
+</code>
 ==== Special fields ====
@@ Línea 70: / Línea 138: @@
 id = models.UUIDField(primary_key=True, default=uuid4, help_text="Unique ID for this particular video")
 </code>
+==== Fields configuration ====
+=== Choice ===
+<code python>
+import calendar
+...
+class MyModel(models.Model):
+    ...
+    MONTH_CHOICES = [(str(i), calendar.month_name[i]) for i in range(1,13)]
+    month = CharField(max_length=9, choices=MONTHS_CHOICES, default='1')
+</code>
 ===== How to... =====
+==== Deal with performed queries ====
+See the current registered queries (with their times):
+<code>
+from django.db import connection
+connection.queries
+</code>
+See a concrete database queries:
+<code>
+from django.db import connections
+connections['my_db_alias'].queries
+</code>
+Delete the query array:
+<code>
+from django.db import reset_queries
+reset_queries()
+</code>
 ==== Get an app model ====
 <code>
 from django.apps import apps
 apps.get_model('users', 'BaseUser')
+</code>
+==== Choose a random element from DB ====
+<code>
+reg = Work(title=random_string_generator(random.randint(5, 15), True),
+           license=License.objects.order_by('?').first(),
+           description=random_string_generator(random.randint(200,2000), True),
+           created=str_time_prop(prop=random.random()),
+           creator=User.objects.order_by('?').first())
+reg.save()
+</code>
+==== Clean migrations ====
+<code>
+find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
+find . -path "*/migrations/*.pyc"  -delete
+</code>
+=== Script to reset the whole DB ===
+<code>
+#!/bin/sh
+export PGPASSWORD=mysecretpassword
+export DATABASE=puma
+find . -path "*/migrations/*.py" -not -name "__init__.py" -delete
+find . -path "*/migrations/*.pyc"  -delete
+dropdb -h 127.0.0.1 -U postgres $DATABASE
+createdb -T template0 -h 127.0.0.1 -U postgres $DATABASE
+python manage.py makemigrations
+python manage.py migrate
+psql -h 127.0.0.1 -U postgres -d $DATABASE -c "INSERT INTO public.pumapp_user (password,last_login,is_superuser,username,first_name,last_name,is_staff,is_active,date_joined,email,current_project_id) VALUES ('pbkdf2_sha256$100000$8RoYX0VMbGIY$OZrZowL8A4pR/wgE/ggy7KOSAU82068MEG3tiZHV70I=',NULL,true,'admin','','',true,true,'2019-01-31 08:22:29.609','admin@a.com',NULL);"
+psql -h 127.0.0.1 -U postgres -d $DATABASE -c "INSERT INTO public.redmine_auth_redmineconfig (url) VALUES ('https://redmine.gtd.es');"
 </code>

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