from django.db import models

class Product(models.Model):

    price = models.IntegerField(null=True)

    discounted_price = models.IntegerField(null=True)

    unit = models.CharField(max_length=15, null=True)

    class Meta:

        required_db_features = {

            "supports_table_check_constraints",

        }

        constraints = [

            models.CheckConstraint(

                check=models.Q(price__gt=models.F("discounted_price")),

                name="price_gt_discounted_price",

            ),

            models.CheckConstraint(

                check=models.Q(price__gt=0),

                name="%(app_label)s_%(class)s_price_gt_0",

            ),

            models.CheckConstraint(

                check=models.Q(

                    models.Q(unit__isnull=True) | models.Q(unit__in=["μg/mL", "ng/mL"])

                ),

                name="unicode_unit_list",

            ),

        ]

class UniqueConstraintProduct(models.Model):

    name = models.CharField(max_length=255)

    color = models.CharField(max_length=32, null=True)

    class Meta:

        constraints = [

            models.UniqueConstraint(fields=["name", "color"], name="name_color_uniq"),

        ]

class ChildUniqueConstraintProduct(UniqueConstraintProduct):

    pass

class UniqueConstraintConditionProduct(models.Model):

    name = models.CharField(max_length=255)

    color = models.CharField(max_length=32, null=True)

    class Meta:

        required_db_features = {"supports_partial_indexes"}

        constraints = [

            models.UniqueConstraint(

                fields=["name"],

                name="name_without_color_uniq",

                condition=models.Q(color__isnull=True),

            ),

        ]

class UniqueConstraintDeferrable(models.Model):

    name = models.CharField(max_length=255)

    shelf = models.CharField(max_length=31)

    class Meta:

        required_db_features = {

            "supports_deferrable_unique_constraints",

        }

        constraints = [

            models.UniqueConstraint(

                fields=["name"],

                name="name_init_deferred_uniq",

                deferrable=models.Deferrable.DEFERRED,

            ),

            models.UniqueConstraint(

                fields=["shelf"],

                name="sheld_init_immediate_uniq",

                deferrable=models.Deferrable.IMMEDIATE,

            ),

        ]

class UniqueConstraintInclude(models.Model):

    name = models.CharField(max_length=255)

    color = models.CharField(max_length=32, null=True)

    class Meta:

        required_db_features = {

            "supports_table_check_constraints",

            "supports_covering_indexes",

        }

        constraints = [

            models.UniqueConstraint(

                fields=["name"],

                name="name_include_color_uniq",

                include=["color"],

            ),

        ]

class AbstractModel(models.Model):

    age = models.IntegerField()

    class Meta:

        abstract = True

        required_db_features = {

            "supports_table_check_constraints",

        }

        constraints = [

            models.CheckConstraint(

                check=models.Q(age__gte=18),

                name="%(app_label)s_%(class)s_adult",

            ),

        ]

class ChildModel(AbstractModel):

    pass