Initial commit. Basic models mostly done.

venv/lib/python3.8/site-packages/django/db/models/constraints.py

@@ -0,0 +1,121 @@
+from django.db.models.query_utils import Q
+from django.db.models.sql.query import Query
+
+__all__ = ['CheckConstraint', 'UniqueConstraint']
+
+
+class BaseConstraint:
+    def __init__(self, name):
+        self.name = name
+
+    def constraint_sql(self, model, schema_editor):
+        raise NotImplementedError('This method must be implemented by a subclass.')
+
+    def create_sql(self, model, schema_editor):
+        raise NotImplementedError('This method must be implemented by a subclass.')
+
+    def remove_sql(self, model, schema_editor):
+        raise NotImplementedError('This method must be implemented by a subclass.')
+
+    def deconstruct(self):
+        path = '%s.%s' % (self.__class__.__module__, self.__class__.__name__)
+        path = path.replace('django.db.models.constraints', 'django.db.models')
+        return (path, (), {'name': self.name})
+
+    def clone(self):
+        _, args, kwargs = self.deconstruct()
+        return self.__class__(*args, **kwargs)
+
+
+class CheckConstraint(BaseConstraint):
+    def __init__(self, *, check, name):
+        self.check = check
+        super().__init__(name)
+
+    def _get_check_sql(self, model, schema_editor):
+        query = Query(model=model)
+        where = query.build_where(self.check)
+        compiler = query.get_compiler(connection=schema_editor.connection)
+        sql, params = where.as_sql(compiler, schema_editor.connection)
+        return sql % tuple(schema_editor.quote_value(p) for p in params)
+
+    def constraint_sql(self, model, schema_editor):
+        check = self._get_check_sql(model, schema_editor)
+        return schema_editor._check_sql(self.name, check)
+
+    def create_sql(self, model, schema_editor):
+        check = self._get_check_sql(model, schema_editor)
+        return schema_editor._create_check_sql(model, self.name, check)
+
+    def remove_sql(self, model, schema_editor):
+        return schema_editor._delete_check_sql(model, self.name)
+
+    def __repr__(self):
+        return "<%s: check='%s' name=%r>" % (self.__class__.__name__, self.check, self.name)
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, CheckConstraint) and
+            self.name == other.name and
+            self.check == other.check
+        )
+
+    def deconstruct(self):
+        path, args, kwargs = super().deconstruct()
+        kwargs['check'] = self.check
+        return path, args, kwargs
+
+
+class UniqueConstraint(BaseConstraint):
+    def __init__(self, *, fields, name, condition=None):
+        if not fields:
+            raise ValueError('At least one field is required to define a unique constraint.')
+        if not isinstance(condition, (type(None), Q)):
+            raise ValueError('UniqueConstraint.condition must be a Q instance.')
+        self.fields = tuple(fields)
+        self.condition = condition
+        super().__init__(name)
+
+    def _get_condition_sql(self, model, schema_editor):
+        if self.condition is None:
+            return None
+        query = Query(model=model)
+        where = query.build_where(self.condition)
+        compiler = query.get_compiler(connection=schema_editor.connection)
+        sql, params = where.as_sql(compiler, schema_editor.connection)
+        return sql % tuple(schema_editor.quote_value(p) for p in params)
+
+    def constraint_sql(self, model, schema_editor):
+        fields = [model._meta.get_field(field_name).column for field_name in self.fields]
+        condition = self._get_condition_sql(model, schema_editor)
+        return schema_editor._unique_sql(model, fields, self.name, condition=condition)
+
+    def create_sql(self, model, schema_editor):
+        fields = [model._meta.get_field(field_name).column for field_name in self.fields]
+        condition = self._get_condition_sql(model, schema_editor)
+        return schema_editor._create_unique_sql(model, fields, self.name, condition=condition)
+
+    def remove_sql(self, model, schema_editor):
+        condition = self._get_condition_sql(model, schema_editor)
+        return schema_editor._delete_unique_sql(model, self.name, condition=condition)
+
+    def __repr__(self):
+        return '<%s: fields=%r name=%r%s>' % (
+            self.__class__.__name__, self.fields, self.name,
+            '' if self.condition is None else ' condition=%s' % self.condition,
+        )
+
+    def __eq__(self, other):
+        return (
+            isinstance(other, UniqueConstraint) and
+            self.name == other.name and
+            self.fields == other.fields and
+            self.condition == other.condition
+        )
+
+    def deconstruct(self):
+        path, args, kwargs = super().deconstruct()
+        kwargs['fields'] = self.fields
+        if self.condition:
+            kwargs['condition'] = self.condition
+        return path, args, kwargs