"""

Giving models a custom manager

You can use a custom ``Manager`` in a particular model by extending the base

``Manager`` class and instantiating your custom ``Manager`` in your model.

There are two reasons you might want to customize a ``Manager``: to add extra

``Manager`` methods, and/or to modify the initial ``QuerySet`` the ``Manager``

returns.

"""

from django.contrib.contenttypes.fields import GenericForeignKey, GenericRelation

from django.db import models

class PersonManager(models.Manager):

    def get_fun_people(self):

        return self.filter(fun=True)

class PublishedBookManager(models.Manager):

    def get_queryset(self):

        return super().get_queryset().filter(is_published=True)

class AnnotatedBookManager(models.Manager):

    def get_queryset(self):

        return (

            super()

            .get_queryset()

            .annotate(favorite_avg=models.Avg("favorite_books__favorite_thing_id"))

        )

class CustomQuerySet(models.QuerySet):

    def filter(self, *args, **kwargs):

        queryset = super().filter(fun=True)

        queryset._filter_CustomQuerySet = True

        return queryset

    def public_method(self, *args, **kwargs):

        return self.all()

    def _private_method(self, *args, **kwargs):

        return self.all()

    def optout_public_method(self, *args, **kwargs):

        return self.all()

    optout_public_method.queryset_only = True

    def _optin_private_method(self, *args, **kwargs):

        return self.all()

    _optin_private_method.queryset_only = False

class BaseCustomManager(models.Manager):

    def __init__(self, arg):

        super().__init__()

        self.init_arg = arg

    def filter(self, *args, **kwargs):

        queryset = super().filter(fun=True)

        queryset._filter_CustomManager = True

        return queryset

    def manager_only(self):

        return self.all()

CustomManager = BaseCustomManager.from_queryset(CustomQuerySet)

class CustomInitQuerySet(models.QuerySet):

    # QuerySet with an __init__() method that takes an additional argument.

    def __init__(

        self, custom_optional_arg=None, model=None, query=None, using=None, hints=None

    ):

        super().__init__(model=model, query=query, using=using, hints=hints)

class DeconstructibleCustomManager(BaseCustomManager.from_queryset(CustomQuerySet)):

    def __init__(self, a, b, c=1, d=2):

        super().__init__(a)

class FunPeopleManager(models.Manager):

    def get_queryset(self):

        return super().get_queryset().filter(fun=True)

class BoringPeopleManager(models.Manager):

    def get_queryset(self):

        return super().get_queryset().filter(fun=False)

class Person(models.Model):

    first_name = models.CharField(max_length=30)

    last_name = models.CharField(max_length=30)

    fun = models.BooleanField(default=False)

    favorite_book = models.ForeignKey(

        "Book", models.SET_NULL, null=True, related_name="favorite_books"

    )

    favorite_thing_type = models.ForeignKey(

        "contenttypes.ContentType", models.SET_NULL, null=True

    )

    favorite_thing_id = models.IntegerField(null=True)

    favorite_thing = GenericForeignKey("favorite_thing_type", "favorite_thing_id")

    objects = PersonManager()

    fun_people = FunPeopleManager()

    boring_people = BoringPeopleManager()

    custom_queryset_default_manager = CustomQuerySet.as_manager()

    custom_queryset_custom_manager = CustomManager("hello")

    custom_init_queryset_manager = CustomInitQuerySet.as_manager()

    def __str__(self):

        return "%s %s" % (self.first_name, self.last_name)

class FunPerson(models.Model):

    first_name = models.CharField(max_length=30)

    last_name = models.CharField(max_length=30)

    fun = models.BooleanField(default=True)

    favorite_book = models.ForeignKey(

        "Book",

        models.SET_NULL,

        null=True,

        related_name="fun_people_favorite_books",

    )

    favorite_thing_type = models.ForeignKey(

        "contenttypes.ContentType", models.SET_NULL, null=True

    )

    favorite_thing_id = models.IntegerField(null=True)

    favorite_thing = GenericForeignKey("favorite_thing_type", "favorite_thing_id")

    objects = FunPeopleManager()

class Book(models.Model):

    title = models.CharField(max_length=50)

    author = models.CharField(max_length=30)

    is_published = models.BooleanField(default=False)

    authors = models.ManyToManyField(Person, related_name="books")

    fun_authors = models.ManyToManyField(FunPerson, related_name="books")

    favorite_things = GenericRelation(

        Person,

        content_type_field="favorite_thing_type",

        object_id_field="favorite_thing_id",

    )

    fun_people_favorite_things = GenericRelation(

        FunPerson,

        content_type_field="favorite_thing_type",

        object_id_field="favorite_thing_id",

    )

    published_objects = PublishedBookManager()

    annotated_objects = AnnotatedBookManager()

    class Meta:

        base_manager_name = "annotated_objects"

class FastCarManager(models.Manager):

    def get_queryset(self):

        return super().get_queryset().filter(top_speed__gt=150)

class Car(models.Model):

    name = models.CharField(max_length=10)

    mileage = models.IntegerField()

    top_speed = models.IntegerField(help_text="In miles per hour.")

    cars = models.Manager()

    fast_cars = FastCarManager()

class FastCarAsBase(Car):

    class Meta:

        proxy = True

        base_manager_name = "fast_cars"

class FastCarAsDefault(Car):

    class Meta:

        proxy = True

        default_manager_name = "fast_cars"

class RestrictedManager(models.Manager):

    def get_queryset(self):

        return super().get_queryset().filter(is_public=True)

class RelatedModel(models.Model):

    name = models.CharField(max_length=50)

class RestrictedModel(models.Model):

    name = models.CharField(max_length=50)

    is_public = models.BooleanField(default=False)

    related = models.ForeignKey(RelatedModel, models.CASCADE)

    objects = RestrictedManager()

    plain_manager = models.Manager()

class OneToOneRestrictedModel(models.Model):

    name = models.CharField(max_length=50)

    is_public = models.BooleanField(default=False)

    related = models.OneToOneField(RelatedModel, models.CASCADE)

    objects = RestrictedManager()

    plain_manager = models.Manager()

class AbstractPerson(models.Model):

    abstract_persons = models.Manager()

    objects = models.CharField(max_length=30)

    class Meta:

        abstract = True

class PersonFromAbstract(AbstractPerson):

    pass