"""

Generic relations

Generic relations let an object have a foreign key to any object through a

content-type/object-id field. A ``GenericForeignKey`` field can point to any

object, be it animal, vegetable, or mineral.

The canonical example is tags (although this example implementation is *far*

from complete).

"""

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

from django.contrib.contenttypes.models import ContentType

from django.db import models

class TaggedItem(models.Model):

    """A tag on an item."""

    tag = models.SlugField()

    content_type = models.ForeignKey(ContentType, models.CASCADE)

    object_id = models.PositiveIntegerField()

    content_object = GenericForeignKey()

    class Meta:

        ordering = ["tag", "content_type__model"]

    def __str__(self):

        return self.tag

class ValuableTaggedItem(TaggedItem):

    value = models.PositiveIntegerField()

class AbstractComparison(models.Model):

    comparative = models.CharField(max_length=50)

    content_type1 = models.ForeignKey(

        ContentType, models.CASCADE, related_name="comparative1_set"

    )

    object_id1 = models.PositiveIntegerField()

    first_obj = GenericForeignKey(ct_field="content_type1", fk_field="object_id1")

class Comparison(AbstractComparison):

    """

    A model that tests having multiple GenericForeignKeys. One is defined

    through an inherited abstract model and one defined directly on this class.

    """

    content_type2 = models.ForeignKey(

        ContentType, models.CASCADE, related_name="comparative2_set"

    )

    object_id2 = models.PositiveIntegerField()

    other_obj = GenericForeignKey(ct_field="content_type2", fk_field="object_id2")

    def __str__(self):

        return "%s is %s than %s" % (self.first_obj, self.comparative, self.other_obj)

class Animal(models.Model):

    common_name = models.CharField(max_length=150)

    latin_name = models.CharField(max_length=150)

    tags = GenericRelation(TaggedItem, related_query_name="animal")

    comparisons = GenericRelation(

        Comparison, object_id_field="object_id1", content_type_field="content_type1"

    )

    def __str__(self):

        return self.common_name

class Vegetable(models.Model):

    name = models.CharField(max_length=150)

    is_yucky = models.BooleanField(default=True)

    tags = GenericRelation(TaggedItem)

    def __str__(self):

        return self.name

class Carrot(Vegetable):

    pass

class Mineral(models.Model):

    name = models.CharField(max_length=150)

    hardness = models.PositiveSmallIntegerField()

    # note the lack of an explicit GenericRelation here...

    def __str__(self):

        return self.name

class GeckoManager(models.Manager):

    def get_queryset(self):

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

class Gecko(models.Model):

    has_tail = models.BooleanField(default=False)

    objects = GeckoManager()

# To test fix for #11263

class Rock(Mineral):

    tags = GenericRelation(TaggedItem)

class ValuableRock(Mineral):

    tags = GenericRelation(ValuableTaggedItem)

class ManualPK(models.Model):

    id = models.IntegerField(primary_key=True)

    tags = GenericRelation(TaggedItem, related_query_name="manualpk")

class ForProxyModelModel(models.Model):

    content_type = models.ForeignKey(ContentType, models.CASCADE)

    object_id = models.PositiveIntegerField()

    obj = GenericForeignKey(for_concrete_model=False)

    title = models.CharField(max_length=255, null=True)

class ForConcreteModelModel(models.Model):

    content_type = models.ForeignKey(ContentType, models.CASCADE)

    object_id = models.PositiveIntegerField()

    obj = GenericForeignKey()

class ConcreteRelatedModel(models.Model):

    bases = GenericRelation(ForProxyModelModel, for_concrete_model=False)

class ProxyRelatedModel(ConcreteRelatedModel):

    class Meta:

        proxy = True

# To test fix for #7551

class AllowsNullGFK(models.Model):

    content_type = models.ForeignKey(ContentType, models.SET_NULL, null=True)

    object_id = models.PositiveIntegerField(null=True)

    content_object = GenericForeignKey()