256 lines
10 KiB
Python
256 lines
10 KiB
Python
from enum import Enum
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from django.db.models.expressions import ExpressionList, F
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from django.db.models.indexes import IndexExpression
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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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__all__ = ['CheckConstraint', 'Deferrable', 'UniqueConstraint']
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class BaseConstraint:
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def __init__(self, name):
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self.name = name
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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 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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return (path, (), {'name': self.name})
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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):
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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 '
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'expression.'
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)
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super().__init__(name)
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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 __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 self.name == other.name and self.check == other.check
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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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):
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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(
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'UniqueConstraint with conditions cannot be deferred.'
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)
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if include and deferrable:
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raise ValueError(
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'UniqueConstraint with include fields cannot be deferred.'
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)
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if opclasses and deferrable:
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raise ValueError(
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'UniqueConstraint with opclasses cannot be deferred.'
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)
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if expressions and deferrable:
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raise ValueError(
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'UniqueConstraint with expressions cannot be deferred.'
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)
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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)
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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 = [model._meta.get_field(field_name).column for field_name in self.include]
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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, fields, self.name, condition=condition,
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deferrable=self.deferrable, include=include,
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opclasses=self.opclasses, 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 = [model._meta.get_field(field_name).column for field_name in self.include]
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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, fields, self.name, condition=condition,
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deferrable=self.deferrable, include=include,
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opclasses=self.opclasses, 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 = [model._meta.get_field(field_name).column for field_name in self.include]
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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, self.name, condition=condition, deferrable=self.deferrable,
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include=include, opclasses=self.opclasses, 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 and
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self.fields == other.fields and
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self.condition == other.condition and
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self.deferrable == other.deferrable and
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self.include == other.include and
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self.opclasses == other.opclasses and
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self.expressions == other.expressions
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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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