Django Web Framework Tutorials

Referencing Django Settings in models.py

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When building a Django application, you may need to reference configuration variables from settings.py in other parts of your code. One common place is in models.py, where you define your database models. Accessing settings allows you to parameterize aspects of your models. For example, you can define the default database or control auto-created fields like timestamps.

Why Access Settings ?

There are a few key reasons why accessing settings in models.py is useful:

First of all, it avoids duplicating configuration values across files. This follows the DRY principle, making your code more maintainable. Any changes can be made in one place – setting’s.py.

Additionally, referencing setting’s allows parts of your model classes to be configurable. As mentioned, you can specify the database or control automatic fields. This allows customizing models without changing code.

Finally, setting’s access enables interaction between components. For example, you can hook model signals into actions defined elsewhere based on a setting value.

Available Approaches

In Django, there are a couple common ways to reference values from setting’s:

Direct Import

The easiest way is to import setting’s directly into models.py and access variables like any other Python code:

from django.conf import settings

class MyModel(models.Model):
  if settings.SOME_FLAG:
    # Do something

While straightforward, some argue this approach pollutes the module namespace.

django.conf.settings

Alternatively, you can reference django.conf.setting's which proxies settings:

from django.db import models

class MyModel(models.Model):
  if django.conf.settings.SOME_FLAG:
      # Do something

This looks cleaner but requires using the full path each reference.

Example Use Cases

To make this concrete, here are some example uses of accessing setting’s in models.py:

Specifying Database

The default database can be parameterized:

class MyModel(models.Model):
  class Meta:
    db_table = django.conf.settings.DB_TABLE_NAME

This table is then created in the configured database.

Controlling Auto Fields

Automatic fields like record creation/update timestamps can be enabled viaSettings:

if settings.ADD_TIMESTAMPS:
  created_at = models.DateTimeField(auto_now_add=True)
  updated_at = models.DateTimeField(auto_now=True)

Signals and Actions

You can tie model events like pre-save signals to external actions based on settings:

from django.db.models.signals import pre_save
from django.dispatch import receiver

@receiver(pre_save, sender=MyModel)
def my_handler(sender, instance, **kwargs):
  if settings.TRIGGER_FUNCTION:
    trigger()

Here the trigger() function only runs if enabled in settings.

Best Practices

When accessing settings in models.py, follow these guidelines:

  • ImportSettings directly at the top, don’t use globals
  • Parameterize values rather than hardcode for maintainability
  • Specify a default inSettings for optional configurations
  • Use descriptive setting names relevant to models

Conclusion

Referencing Django settings in models.py enables code reuse, customization, and interaction between components. Both direct imports and the django.conf.settings proxy are available. Common use cases include specifying databases, controlling automatic fields, and hooking model events to external triggers. Follow naming and design best practices to keep your code clean.