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wiki2:python:django:models
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| Ambos lados, revisión anterior Revisión previa Próxima revisión | Revisión previa | ||
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wiki2:python:django:models [2019/01/31 07:42] alfred [Clean migrations] |
wiki2:python:django:models [2020/05/09 09:25] (actual) |
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| ====== Django Models ====== | ====== Django Models ====== | ||
| + | ===== Migrations ===== | ||
| + | |||
| + | <code> | ||
| + | $ python manage.py makemigrations <app> | ||
| + | </code> | ||
| + | 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 ===== | ===== Signals ===== | ||
| Línea 60: | Línea 71: | ||
| ===== Fields ===== | ===== 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 ==== | ==== Image Field ==== | ||
| Línea 89: | Línea 110: | ||
| </code> | </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 ==== | ==== Special fields ==== | ||
| Línea 114: | Línea 158: | ||
| ===== How to... ===== | ===== 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 ==== | ==== Get an app model ==== | ||
| <code> | <code> | ||
wiki2/python/django/models.1548920575.txt.gz · Última modificación: 2020/05/09 09:24 (editor externo)
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