Django - Reference

best practices

• models field
  • use help_text as documentation
  • use unique=True is this field must be unique throughout the table
• graphene
  • List consider using NonNull = graphene.List(graphene.NonNull(graphene.String))
  • required=True or ObjectType

class DocumentUploaderFormConfig(graphene.ObjectType):
    enum_name = graphene.String(required=True)

class DocumentUploadConfigQuery(graphene.ObjectType):
    document_uploader_form_configs = graphene.List(graphene.NonNull(DocumentUploaderFormConfig)), required=True)

Django - How To

debugging/pdb for dockerised django

1. add breakpoint() in code
2. run the following bash command

docker container ls
docker attach ID # ID is the container id for oneview-django image

use Q & F

• Q() - represents an SQL condition that can be used in database-related operations
• F() - represents the value of a model field or annotation

These two make it possible to define and reuse conditions.

use GraphiQL with django debug tool bar

1. login to http://localhost:8000/admin/
2. go to http://localhost:8000/graphql/
3. copy paste both the graphql query and graphql variable from the graphql request plugin
4. run the added query in graphiql
5. look at the django debug toolbar

count distinct values in django orm

from django.db.models import Count

Contact.objects.all().values('ff_status').annotate(Count('ff_status'))

Django - Explanation

codebase uses lot of inheritances

Django likes subclassing existing class.

RelatedManager subclasses Manager to get all method from managers.

Create a manager for the reverse side of a many-to-one relation.

This manager subclasses another manager, generally the default manager of the related model, and adds behaviors specific to many-to-one relations.

https://github.com/django/django/blob/a09082a9bec18f8e3ee8c10d473013ec67ffe93b/django/db/models/fields/related_descriptors.py#L675C5-L675C45

Manager is a subclass of QuerySet so that manager has all the methods of QuerySet.

class Manager(BaseManager.from_queryset(QuerySet)): pass

https://github.com/django/django/blob/f030236a86a64a4befd3cc8093e2bbeceef52a31/django/db/models/manager.py#L176