Django Model Mixins and Utilities simplify coding by providing pre-defined algorithms for common tasks, including custom queries, filtering, and data validation. This software library also offers built-in support for time and date management, string handling, and more.
The django-model-utils software package is built for Django models and includes mixins and utilities. One of the notable features is the InheritanceCastModel abstract base class, which is designed for the parent model in a model-inheritance hierarchy. With InheritanceCastModel, the child model instances know what type they are by using an automatically-set foreign key to ContentType. This feature enables automatic casting of a parent instance to its corresponding leaf child instance.
As an example, if a model called Place has subclasses Restaurant and Bar, querying all Places will only return Place instances, even for objects that are actually Restaurant or Bar. However, if Place inherits from InheritanceCastModel, the cast() method can be called on each Place. This method will return an instance of the correct subtype: either Restaurant or Bar.
It is worth noting that for large querysets, the cast() method is inefficient, as it results in n queries to the subtype tables. However, it is possible to write a QuerySet subclass to minimize this inefficiency to k queries for k subtypes in the inheritance tree.
Another feature of the django-model-utils package is the TimeStampedModel abstract base class. This class provides self-updating created and modified fields for any model that inherits it. The created field is automatically set when a new instance is created, while the modified field updates itself every time the instance is modified.
Overall, the django-model-utils package is a useful tool for developers working with Django models. Its mixins and utilities like InheritanceCastModel and TimeStampedModel can help streamline the model-inheritance process and reduce the workload for developers.
As an example, if a model called Place has subclasses Restaurant and Bar, querying all Places will only return Place instances, even for objects that are actually Restaurant or Bar. However, if Place inherits from InheritanceCastModel, the cast() method can be called on each Place. This method will return an instance of the correct subtype: either Restaurant or Bar.
It is worth noting that for large querysets, the cast() method is inefficient, as it results in n queries to the subtype tables. However, it is possible to write a QuerySet subclass to minimize this inefficiency to k queries for k subtypes in the inheritance tree.
Another feature of the django-model-utils package is the TimeStampedModel abstract base class. This class provides self-updating created and modified fields for any model that inherits it. The created field is automatically set when a new instance is created, while the modified field updates itself every time the instance is modified.
Overall, the django-model-utils package is a useful tool for developers working with Django models. Its mixins and utilities like InheritanceCastModel and TimeStampedModel can help streamline the model-inheritance process and reduce the workload for developers.
What's New
Version 0.3.1: N/A