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POHow to make a base class when childs can't inherit?
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  1. POHow to make a base class when childs can't inherit?
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    copied!<p>I have a fairly simple model in Django, let's say <code>Book</code>:</p> <pre><code>class Book(models.Model): name = models.CharField(max_length=255, default="") description = models.TextField(null=True, blank=True) creation_date = models.DateTimeField() </code></pre> <p>Because the structure and data basically comes from an external API, I have contained it in its own app and I rather not want to modify it.</p> <p>Now I want to add another source of different books to the project and I'm not really sure what the best solution is here.</p> <p>Let's say the second model is:</p> <pre><code>class NextBook(models.Model): title = models.CharField(max_length=255, default="") long_description = models.TextField(null=True, blank=True) created = models.DateTimeField() </code></pre> <p>So the basic fields are there, but have different names. To get the two together, I can probably use another model with a GenericForeignKey:</p> <pre><code>class BaseBook(models.Model): book_type = models.ForeignKey(ContentType) book_id = models.PositiveIntegerField() book_object = generic.GenericForeignKey('book_type', 'book_id') </code></pre> <p>But then I cannot query for all the book as e.g. <code>BaseBook.objects.all().order_by('created')</code> wouldn't work. Surely, I could go on and duplicate a datetime field in the base model and then the title and so on, but I think that would be the wrong direction. Also inheritance seems not a choice if I don't want to touch the specific models.</p> <p>I am looking for some design pattern or something that let's me efficiently 'plug in' more providers and query for all objects, while not making a huge mess of model structure and database queries.</p>
 

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