372 lines
15 KiB
Python
372 lines
15 KiB
Python
from enum import Enum
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from django.core.exceptions import FieldError, ValidationError
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from django.db import connections
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from django.db.models.expressions import Exists, ExpressionList, F, OrderBy
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from django.db.models.indexes import IndexExpression
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from django.db.models.lookups import Exact
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from django.db.models.query_utils import Q
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from django.db.models.sql.query import Query
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from django.db.utils import DEFAULT_DB_ALIAS
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from django.utils.translation import gettext_lazy as _
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__all__ = ["BaseConstraint", "CheckConstraint", "Deferrable", "UniqueConstraint"]
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class BaseConstraint:
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default_violation_error_message = _("Constraint “%(name)s” is violated.")
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violation_error_message = None
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def __init__(self, name, violation_error_message=None):
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self.name = name
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if violation_error_message is not None:
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self.violation_error_message = violation_error_message
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else:
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self.violation_error_message = self.default_violation_error_message
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@property
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def contains_expressions(self):
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return False
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def constraint_sql(self, model, schema_editor):
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raise NotImplementedError("This method must be implemented by a subclass.")
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def create_sql(self, model, schema_editor):
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raise NotImplementedError("This method must be implemented by a subclass.")
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def remove_sql(self, model, schema_editor):
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raise NotImplementedError("This method must be implemented by a subclass.")
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def validate(self, model, instance, exclude=None, using=DEFAULT_DB_ALIAS):
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raise NotImplementedError("This method must be implemented by a subclass.")
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def get_violation_error_message(self):
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return self.violation_error_message % {"name": self.name}
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def deconstruct(self):
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path = "%s.%s" % (self.__class__.__module__, self.__class__.__name__)
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path = path.replace("django.db.models.constraints", "django.db.models")
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kwargs = {"name": self.name}
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if (
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self.violation_error_message is not None
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and self.violation_error_message != self.default_violation_error_message
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):
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kwargs["violation_error_message"] = self.violation_error_message
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return (path, (), kwargs)
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def clone(self):
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_, args, kwargs = self.deconstruct()
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return self.__class__(*args, **kwargs)
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class CheckConstraint(BaseConstraint):
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def __init__(self, *, check, name, violation_error_message=None):
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self.check = check
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if not getattr(check, "conditional", False):
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raise TypeError(
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"CheckConstraint.check must be a Q instance or boolean expression."
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)
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super().__init__(name, violation_error_message=violation_error_message)
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def _get_check_sql(self, model, schema_editor):
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query = Query(model=model, alias_cols=False)
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where = query.build_where(self.check)
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compiler = query.get_compiler(connection=schema_editor.connection)
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sql, params = where.as_sql(compiler, schema_editor.connection)
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return sql % tuple(schema_editor.quote_value(p) for p in params)
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def constraint_sql(self, model, schema_editor):
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check = self._get_check_sql(model, schema_editor)
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return schema_editor._check_sql(self.name, check)
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def create_sql(self, model, schema_editor):
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check = self._get_check_sql(model, schema_editor)
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return schema_editor._create_check_sql(model, self.name, check)
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def remove_sql(self, model, schema_editor):
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return schema_editor._delete_check_sql(model, self.name)
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def validate(self, model, instance, exclude=None, using=DEFAULT_DB_ALIAS):
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against = instance._get_field_value_map(meta=model._meta, exclude=exclude)
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try:
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if not Q(self.check).check(against, using=using):
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raise ValidationError(self.get_violation_error_message())
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except FieldError:
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pass
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def __repr__(self):
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return "<%s: check=%s name=%s>" % (
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self.__class__.__qualname__,
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self.check,
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repr(self.name),
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)
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def __eq__(self, other):
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if isinstance(other, CheckConstraint):
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return (
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self.name == other.name
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and self.check == other.check
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and self.violation_error_message == other.violation_error_message
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)
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return super().__eq__(other)
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def deconstruct(self):
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path, args, kwargs = super().deconstruct()
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kwargs["check"] = self.check
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return path, args, kwargs
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class Deferrable(Enum):
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DEFERRED = "deferred"
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IMMEDIATE = "immediate"
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# A similar format was proposed for Python 3.10.
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def __repr__(self):
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return f"{self.__class__.__qualname__}.{self._name_}"
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class UniqueConstraint(BaseConstraint):
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def __init__(
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self,
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*expressions,
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fields=(),
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name=None,
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condition=None,
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deferrable=None,
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include=None,
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opclasses=(),
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violation_error_message=None,
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):
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if not name:
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raise ValueError("A unique constraint must be named.")
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if not expressions and not fields:
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raise ValueError(
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"At least one field or expression is required to define a "
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"unique constraint."
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)
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if expressions and fields:
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raise ValueError(
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"UniqueConstraint.fields and expressions are mutually exclusive."
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)
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if not isinstance(condition, (type(None), Q)):
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raise ValueError("UniqueConstraint.condition must be a Q instance.")
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if condition and deferrable:
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raise ValueError("UniqueConstraint with conditions cannot be deferred.")
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if include and deferrable:
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raise ValueError("UniqueConstraint with include fields cannot be deferred.")
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if opclasses and deferrable:
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raise ValueError("UniqueConstraint with opclasses cannot be deferred.")
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if expressions and deferrable:
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raise ValueError("UniqueConstraint with expressions cannot be deferred.")
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if expressions and opclasses:
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raise ValueError(
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"UniqueConstraint.opclasses cannot be used with expressions. "
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"Use django.contrib.postgres.indexes.OpClass() instead."
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)
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if not isinstance(deferrable, (type(None), Deferrable)):
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raise ValueError(
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"UniqueConstraint.deferrable must be a Deferrable instance."
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)
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if not isinstance(include, (type(None), list, tuple)):
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raise ValueError("UniqueConstraint.include must be a list or tuple.")
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if not isinstance(opclasses, (list, tuple)):
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raise ValueError("UniqueConstraint.opclasses must be a list or tuple.")
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if opclasses and len(fields) != len(opclasses):
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raise ValueError(
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"UniqueConstraint.fields and UniqueConstraint.opclasses must "
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"have the same number of elements."
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)
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self.fields = tuple(fields)
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self.condition = condition
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self.deferrable = deferrable
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self.include = tuple(include) if include else ()
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self.opclasses = opclasses
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self.expressions = tuple(
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F(expression) if isinstance(expression, str) else expression
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for expression in expressions
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)
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super().__init__(name, violation_error_message=violation_error_message)
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@property
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def contains_expressions(self):
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return bool(self.expressions)
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def _get_condition_sql(self, model, schema_editor):
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if self.condition is None:
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return None
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query = Query(model=model, alias_cols=False)
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where = query.build_where(self.condition)
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compiler = query.get_compiler(connection=schema_editor.connection)
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sql, params = where.as_sql(compiler, schema_editor.connection)
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return sql % tuple(schema_editor.quote_value(p) for p in params)
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def _get_index_expressions(self, model, schema_editor):
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if not self.expressions:
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return None
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index_expressions = []
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for expression in self.expressions:
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index_expression = IndexExpression(expression)
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index_expression.set_wrapper_classes(schema_editor.connection)
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index_expressions.append(index_expression)
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return ExpressionList(*index_expressions).resolve_expression(
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Query(model, alias_cols=False),
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)
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def constraint_sql(self, model, schema_editor):
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fields = [model._meta.get_field(field_name) for field_name in self.fields]
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include = [
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model._meta.get_field(field_name).column for field_name in self.include
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]
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condition = self._get_condition_sql(model, schema_editor)
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expressions = self._get_index_expressions(model, schema_editor)
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return schema_editor._unique_sql(
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model,
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fields,
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self.name,
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condition=condition,
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deferrable=self.deferrable,
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include=include,
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opclasses=self.opclasses,
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expressions=expressions,
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)
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def create_sql(self, model, schema_editor):
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fields = [model._meta.get_field(field_name) for field_name in self.fields]
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include = [
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model._meta.get_field(field_name).column for field_name in self.include
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]
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condition = self._get_condition_sql(model, schema_editor)
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expressions = self._get_index_expressions(model, schema_editor)
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return schema_editor._create_unique_sql(
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model,
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fields,
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self.name,
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condition=condition,
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deferrable=self.deferrable,
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include=include,
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opclasses=self.opclasses,
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expressions=expressions,
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)
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def remove_sql(self, model, schema_editor):
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condition = self._get_condition_sql(model, schema_editor)
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include = [
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model._meta.get_field(field_name).column for field_name in self.include
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]
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expressions = self._get_index_expressions(model, schema_editor)
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return schema_editor._delete_unique_sql(
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model,
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self.name,
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condition=condition,
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deferrable=self.deferrable,
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include=include,
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opclasses=self.opclasses,
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expressions=expressions,
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)
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def __repr__(self):
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return "<%s:%s%s%s%s%s%s%s>" % (
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self.__class__.__qualname__,
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"" if not self.fields else " fields=%s" % repr(self.fields),
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"" if not self.expressions else " expressions=%s" % repr(self.expressions),
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" name=%s" % repr(self.name),
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"" if self.condition is None else " condition=%s" % self.condition,
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"" if self.deferrable is None else " deferrable=%r" % self.deferrable,
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"" if not self.include else " include=%s" % repr(self.include),
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"" if not self.opclasses else " opclasses=%s" % repr(self.opclasses),
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)
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def __eq__(self, other):
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if isinstance(other, UniqueConstraint):
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return (
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self.name == other.name
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and self.fields == other.fields
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and self.condition == other.condition
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and self.deferrable == other.deferrable
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and self.include == other.include
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and self.opclasses == other.opclasses
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and self.expressions == other.expressions
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and self.violation_error_message == other.violation_error_message
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)
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return super().__eq__(other)
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def deconstruct(self):
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path, args, kwargs = super().deconstruct()
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if self.fields:
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kwargs["fields"] = self.fields
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if self.condition:
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kwargs["condition"] = self.condition
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if self.deferrable:
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kwargs["deferrable"] = self.deferrable
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if self.include:
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kwargs["include"] = self.include
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if self.opclasses:
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kwargs["opclasses"] = self.opclasses
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return path, self.expressions, kwargs
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def validate(self, model, instance, exclude=None, using=DEFAULT_DB_ALIAS):
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queryset = model._default_manager.using(using)
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if self.fields:
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lookup_kwargs = {}
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for field_name in self.fields:
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if exclude and field_name in exclude:
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return
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field = model._meta.get_field(field_name)
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lookup_value = getattr(instance, field.attname)
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if lookup_value is None or (
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lookup_value == ""
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and connections[using].features.interprets_empty_strings_as_nulls
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):
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# A composite constraint containing NULL value cannot cause
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# a violation since NULL != NULL in SQL.
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return
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lookup_kwargs[field.name] = lookup_value
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queryset = queryset.filter(**lookup_kwargs)
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else:
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# Ignore constraints with excluded fields.
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if exclude:
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for expression in self.expressions:
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if hasattr(expression, "flatten"):
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for expr in expression.flatten():
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if isinstance(expr, F) and expr.name in exclude:
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return
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elif isinstance(expression, F) and expression.name in exclude:
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return
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replacements = {
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F(field): value
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for field, value in instance._get_field_value_map(
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meta=model._meta, exclude=exclude
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).items()
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}
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expressions = []
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for expr in self.expressions:
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# Ignore ordering.
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if isinstance(expr, OrderBy):
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expr = expr.expression
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expressions.append(Exact(expr, expr.replace_expressions(replacements)))
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queryset = queryset.filter(*expressions)
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model_class_pk = instance._get_pk_val(model._meta)
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if not instance._state.adding and model_class_pk is not None:
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queryset = queryset.exclude(pk=model_class_pk)
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if not self.condition:
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if queryset.exists():
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if self.expressions:
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raise ValidationError(self.get_violation_error_message())
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# When fields are defined, use the unique_error_message() for
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# backward compatibility.
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for model, constraints in instance.get_constraints():
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for constraint in constraints:
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if constraint is self:
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raise ValidationError(
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instance.unique_error_message(model, self.fields)
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)
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else:
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against = instance._get_field_value_map(meta=model._meta, exclude=exclude)
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try:
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if (self.condition & Exists(queryset.filter(self.condition))).check(
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against, using=using
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):
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raise ValidationError(self.get_violation_error_message())
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except FieldError:
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pass
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