[Django]-Django select_related() and GenericForeignKey

by

-1👍

You could try to refactor your database to look somewhat like this:

class Comment(models.Model):
    ...
    content_object = models.ForeignKey(Content)

class Content(models.Model):
    text = models.CharField(max_length=123)

class SomeSpecificContent(models.Model):
    ...
    content = models.ForeignKey(Content)

class OtherSpecificContent(models.Model):
    ...
    content = models.ForeignKey(Content)

which in case of Django would actually be a very similar schema to that of:

class Comment(models.Model):
    ...
    content_object = models.ForeignKey(Content)

class Content(models.Model):
    text = models.TextField()

class SomeSpecificContent(Content):
    ...

class OtherSpecificContent(Content):
    ...

as that is basically how the inheritence is handled in Django. The latter is probably less flexible and might be a little bit difficult to understand in case where SomeSpecificContent and OtherSpecificContent in fact represent totally different concepts.

Generic relations on the other hand cannot be handled efficiently exactly for this reason that they can link with whatever table you want them to. Therefore if you have a list of 5 objects it might happen, that each one of them is related to a different type of entity. Not sure how Django handles the case where 100 objects are related to 5 types of entities. Does it in fact generate 5+1 queries?

👤julx

Leave a comment