Content type
What if you want to write a general query in Django just like a function which take some argument and then perform some action. This is where contenttypes app shines in Django.
This app comes pre-installed with Django.
The purpose of this application (contenttypes) is to track all other apps installed and model inside those app in your project.
suppose you have app named core and a model inside it as Account, then after migration you will get a entry in contentype table as app_label = core, and model = account.
For example I have an app as core and model inside it as restaurant and now this is how contenttype table created by contenttype model inside contenttypes app given by default from Django will look like.
| id | app_label | model |
|---|---|---|
| 1 | admin | logentry |
| 2 | auth | permission |
| 3 | auth | group |
| 4 | auth | user |
| 5 | contenttypes | contenttype |
| 6 | sessions | session |
| 7 | core | restaurant |
To see objects of contenttype model we can perform normal Django ORM query. for example
from django.contrib.contenttypes.models import ContentType
content_type = ContentType.objects.all()
print(content_type)
<QuerySet [<ContentType: admin | log entry>, <ContentType: auth | permission>, <ContentType: auth | group>, <ContentType: auth | user>, <ContentType: contenttypes | content type>, <ContentType: sessions | session>, <ContentType: core | restaurant>, <ContentType: core | rating>, <ContentType: core | sale>, <ContentType: core | order>, <ContentType: core | product>]>Now since we know that contenttype has app_label and model as it’s field.
we can perform following query:
content_type = ContentType.objects.get(app_label='core', model='restaurant')
app_model = content_type.model_class()
all_objects = app_model.objects.all()
print(all_objects)
<QuerySet [<Restaurant: Pizzeria 1>, <Restaurant: Pizzeria 2>, <Restaurant: Golden Dragon>, <Restaurant: Bombay Bustle>, <Restaurant: McDonalds>, <Restaurant: Taco Bell>, <Restaurant: Chinese 2>, <Restaurant: Chinese 3>, <Restaurant: Indian 2>, <Restaurant: Mexican 1>, <Restaurant: Mexican 2>, <Restaurant: Pizzeria 3>, <Restaurant: Pizzeria 4>, <Restaurant: Italian 1>]>
This query can be encapsulate and then can be re-used by just passing the model and class name.
So basically in this way we can encapsulate a query to be performed repeatedly on different app and model.