100 lines
3.5 KiB
Python
100 lines
3.5 KiB
Python
from django.db.models.sql.query import Query
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__all__ = ['CheckConstraint', '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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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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super().__init__(name)
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def _get_check_sql(self, model, schema_editor):
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query = Query(model=model)
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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=%r>" % (self.__class__.__name__, self.check, self.name)
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def __eq__(self, other):
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return (
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isinstance(other, CheckConstraint) and
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self.name == other.name and
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self.check == other.check
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)
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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 UniqueConstraint(BaseConstraint):
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def __init__(self, *, fields, name):
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if not fields:
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raise ValueError('At least one field is required to define a unique constraint.')
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self.fields = tuple(fields)
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super().__init__(name)
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def constraint_sql(self, model, schema_editor):
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fields = [model._meta.get_field(field_name).column for field_name in self.fields]
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return schema_editor._unique_sql(fields, self.name)
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def create_sql(self, model, schema_editor):
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fields = [model._meta.get_field(field_name).column for field_name in self.fields]
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return schema_editor._create_unique_sql(model, fields, self.name)
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def remove_sql(self, model, schema_editor):
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return schema_editor._delete_unique_sql(model, self.name)
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def __repr__(self):
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return '<%s: fields=%r name=%r>' % (self.__class__.__name__, self.fields, self.name)
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def __eq__(self, other):
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return (
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isinstance(other, UniqueConstraint) and
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self.name == other.name and
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self.fields == other.fields
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)
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def deconstruct(self):
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path, args, kwargs = super().deconstruct()
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kwargs['fields'] = self.fields
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return path, args, kwargs
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