text: try:
      from collections import OrderedDict
  except ImportError:
      from ordereddict import OrderedDict
  from functools import partial
  from inspect import isclass
  from itertools import chain
  from operator import attrgetter
  import six
  import sqlalchemy as sa
  from sqlalchemy.ext.hybrid import hybrid_property
  from sqlalchemy.orm import mapperlib
  from sqlalchemy.orm.attributes import InstrumentedAttribute
  from sqlalchemy.orm.exc import UnmappedInstanceError
  from sqlalchemy.orm.properties import ColumnProperty
  from sqlalchemy.orm.query import _ColumnEntity
  from sqlalchemy.orm.session import object_session
  from sqlalchemy.orm.util import AliasedInsp
  from sqlalchemy_utils.utils import is_sequence
  
  
  def get_column_key(model, column):
      """
      Return the key for given column in given model.
  
      :param model: SQLAlchemy declarative model object
  
      ::
  
          class User(Base):
              __tablename__ = 'user'
              id = sa.Column(sa.Integer, primary_key=True)
              name = sa.Column('_name', sa.String)
  
  
          get_column_key(User, User.__table__.c._name)  # 'name'
  
      .. versionadded: 0.26.5
  
      .. versionchanged: 0.27.11
          Throws UnmappedColumnError instead of ValueError when no property was
          found for given column. This is consistent with how SQLAlchemy works.
      """
      mapper = sa.inspect(model)
      try:
          return mapper.get_property_by_column(column).key
      except sa.orm.exc.UnmappedColumnError:
          for key, c in mapper.columns.items():
              if c.name == column.name and c.table is column.table:
                  return key
      raise sa.orm.exc.UnmappedColumnError(
          'No column %s is configured on mapper %s...' %
          (column, mapper)
      )
  
  
  def get_mapper(mixed):
      """
      Return related SQLAlchemy Mapper for given SQLAlchemy object.
  
      :param mixed: SQLAlchemy Table / Alias / Mapper / declarative model object
  
      ::
  
          from sqlalchemy_utils import get_mapper
  
  
          get_mapper(User)
  
          get_mapper(User())
  
          get_mapper(User.__table__)
  
          get_mapper(User.__mapper__)
  
          get_mapper(sa.orm.aliased(User))
  
          get_mapper(sa.orm.aliased(User.__table__))
  
  
      Raises:
          ValueError: if multiple mappers were found for given argument
  
      .. versionadded: 0.26.1
      """
      if isinstance(mixed, sa.orm.query._MapperEntity):
          mixed = mixed.expr
      elif isinstance(mixed, sa.Column):
          mixed = mixed.table
      elif isinstance(mixed, sa.orm.query._ColumnEntity):
          mixed = mixed.expr
  
      if isinstance(mixed, sa.orm.Mapper):
          return mixed
      if isinstance(mixed, sa.orm.util.AliasedClass):
          return sa.inspect(mixed).mapper
      if isinstance(mixed, sa.sql.selectable.Alias):
          mixed = mixed.element
      if isinstance(mixed, AliasedInsp):
          return mixed.mapper
      if isinstance(mixed, sa.orm.attributes.InstrumentedAttribute):
          mixed = mixed.class_
      if isinstance(mixed, sa.Table):
          mappers = [
              mapper for mapper in mapperlib._mapper_registry
              if mixed in mapper.tables
          ]
          if len(mappers) > 1:
              raise ValueError(
                  "Multiple mappers found for table '%s'." % mixed.name
              )
          elif not mappers:
              raise ValueError(
                  "Could not get mapper for table '%s'." % mixed.name
              )
          else:
              return mappers[0]
      if not isclass(mixed):
          mixed = type(mixed)
      return sa.inspect(mixed)
  
  
  def get_bind(obj):
      """
      Return the bind for given SQLAlchemy Engine / Connection / declarative
      model object.
  
      :param obj: SQLAlchemy Engine / Connection / declarative model object
  
      ::
  
          from sqlalchemy_utils import get_bind
  
  
          get_bind(session)  # Connection object
  
          get_bind(user)
  
      """
      if hasattr(obj, 'bind'):
          conn = obj.bind
      else:
          try:
              conn = object_session(obj).bind
          except UnmappedInstanceError:
              conn = obj
  
      if not hasattr(conn, 'execute'):
          raise TypeError(
              'This method accepts only Session, Engine, Connection and '
              'declarative model objects.'
          )
      return conn
  
  
  def get_primary_keys(mixed):
      """
      Return an OrderedDict of all primary keys for given Table object,
      declarative class or declarative class instance.
  
      :param mixed:
          SA Table object, SA declarative class or SA declarative class instance
  
      ::
  
          get_primary_keys(User)
  
          get_primary_keys(User())
  
          get_primary_keys(User.__table__)
  
          get_primary_keys(User.__mapper__)
  
          get_primary_keys(sa.orm.aliased(User))
  
          get_primary_keys(sa.orm.aliased(User.__table__))
  
  
      .. versionchanged: 0.25.3
          Made the function return an ordered dictionary instead of generator.
          This change was made to support primary key aliases.
  
          Renamed this function to 'get_primary_keys', formerly 'primary_keys'
  
      .. seealso:: :func:`get_columns`
      """
      return OrderedDict(
          (
              (key, column) for key, column in get_columns(mixed).items()
              if column.primary_key
          )
      )
  
  
  def get_tables(mixed):
      """
      Return a set of tables associated with given SQLAlchemy object.
  
      Let's say we have three classes which use joined table inheritance
      TextItem, Article and BlogPost. Article and BlogPost inherit TextItem.
  
      ::
  
          get_tables(Article)  # set([Table('article', ...), Table('text_item')])
  
          get_tables(Article())
  
          get_tables(Article.__mapper__)
  
  
      If the TextItem entity is using with_polymorphic='*' then this function
      returns all child tables (article and blog_post) as well.
  
      ::
  
  
          get_tables(TextItem)  # set([Table('text_item', ...)], ...])
  
  
      .. versionadded: 0.26.0
  
      :param mixed:
          SQLAlchemy Mapper, Declarative class, Column, InstrumentedAttribute or
          a SA Alias object wrapping any of these objects.
      """
      if isinstance(mixed, sa.Table):
          return [mixed]
      elif isinstance(mixed, sa.Column):
          return [mixed.table]
      elif isinstance(mixed, sa.orm.attributes.InstrumentedAttribute):
          return mixed.parent.tables
      elif isinstance(mixed, sa.orm.query._ColumnEntity):
          mixed = mixed.expr
  
      mapper = get_mapper(mixed)
  
      polymorphic_mappers = get_polymorphic_mappers(mapper)
      if polymorphic_mappers:
          tables = sum((m.tables for m in polymorphic_mappers), [])
      else:
          tables = mapper.tables
      return tables
  
  
  def get_columns(mixed):
      """
      Return a collection of all Column objects for given SQLAlchemy
      object.
  
      The type of the collection depends on the type of the object to return the
      columns from.
  
      ::
  
          get_columns(User)
  
          get_columns(User())
  
          get_columns(User.__table__)
  
          get_columns(User.__mapper__)
  
          get_columns(sa.orm.aliased(User))
  
          get_columns(sa.orm.alised(User.__table__))
  
  
      :param mixed:
          SA Table object, SA Mapper, SA declarative class, SA declarative class
          instance or an alias of any of these objects
      """
      if isinstance(mixed, sa.Table):
          return mixed.c
      if isinstance(mixed, sa.orm.util.AliasedClass):
          return sa.inspect(mixed).mapper.columns
      if isinstance(mixed, sa.sql.selectable.Alias):
          return mixed.c
      if isinstance(mixed, sa.orm.Mapper):
          return mixed.columns
      if not isclass(mixed):
          mixed = mixed.__class__
      return sa.inspect(mixed).columns
  
  
  def table_name(obj):
      """
      Return table name of given target, declarative class or the
      table name where the declarative attribute is bound to.
      """
      class_ = getattr(obj, 'class_', obj)
  
      try:
          return class_.__tablename__
      except AttributeError:
          pass
  
      try:
          return class_.__table__.name
      except AttributeError:
          pass
  
  
  def getattrs(obj, attrs):
      return map(partial(getattr, obj), attrs)
  
  
  def local_values(prop, entity):
      return tuple(getattrs(entity, local_column_names(prop)))
  
  
  def list_local_values(prop, entities):
      return map(partial(local_values, prop), entities)
  
  
  def remote_values(prop, entity):
      return tuple(getattrs(entity, remote_column_names(prop)))
  
  
  def local_remote_expr(prop, entity):
      return sa.and_(
          *[
              getattr(remote(prop), r.name)
              ==
              getattr(entity, l.name)
              for l, r in prop.local_remote_pairs
              if r in remote_column_names(prop)
          ]
      )
  
  
  def list_local_remote_exprs(prop, entities):
      return map(partial(local_remote_expr, prop), entities)
  
  
  def remote(prop):
      try:
          return prop.secondary.c
      except AttributeError:
          return prop.mapper.class_
  
  
  def local_column_names(prop):
      if not hasattr(prop, 'secondary'):
          yield prop._discriminator_col.key
          for id_col in prop._id_cols:
              yield id_col.key
      elif prop.secondary is None:
          for local, _ in prop.local_remote_pairs:
              yield local.name
      else:
          if prop.secondary is not None:
              for local, remote in prop.local_remote_pairs:
                  for fk in remote.foreign_keys:
                      if fk.column.table in prop.parent.tables:
                          yield local.name
  
  
  def remote_column_names(prop):
      if not hasattr(prop, 'secondary'):
          yield '__tablename__'
          yield 'id'
      elif prop.secondary is None:
          for _, remote in prop.local_remote_pairs:
              yield remote.name
      else:
          for _, remote in prop.local_remote_pairs:
              for fk in remote.foreign_keys:
                  if fk.column.table in prop.parent.tables:
                      yield remote.name
  
  
  def quote(mixed, ident):
      """
      Conditionally quote an identifier.
      ::
  
  
          from sqlalchemy_utils import quote
  
  
          engine = create_engine('sqlite:///:memory:')
  
          quote(engine, 'order')
          # '"order"'
  
          quote(engine, 'some_other_identifier')
          # 'some_other_identifier'
  
  
      :param mixed: SQLAlchemy Session / Connection / Engine object.
      :param ident: identifier to conditionally quote
      """
      dialect = get_bind(mixed).dialect
      return dialect.preparer(dialect).quote(ident)
  
  
  def query_labels(query):
      """
      Return all labels for given SQLAlchemy query object.
  
      Example::
  
  
          query = session.query(
              Category,
              db.func.count(Article.id).label('articles')
          )
  
          query_labels(query)  # ['articles']
  
      :param query: SQLAlchemy Query object
      """
      return [
          entity._label_name for entity in query._entities
          if isinstance(entity, _ColumnEntity) and entity._label_name
      ]
  
  
  def get_query_entities(query):
      """
      Return a list of all entities present in given SQLAlchemy query object.
  
      Examples::
  
  
          from sqlalchemy_utils import get_query_entities
  
  
          query = session.query(Category)
  
          get_query_entities(query)  # [<Category>]
  
  
          query = session.query(Category.id)
  
          get_query_entities(query)  # [<Category>]
  
  
      This function also supports queries with joins.
  
      ::
  
  
          query = session.query(Category).join(Article)
  
          get_query_entities(query)  # [<Category>, <Article>]
  
      .. versionchanged: 0.26.7
          This function now returns a list instead of generator
  
      :param query: SQLAlchemy Query object
      """
      return [
          get_query_entity(entity) for entity in
          chain(query._entities, query._join_entities)
      ]
  
  
  def get_query_entity(mixed):
      if hasattr(mixed, 'expr'):
          expr = mixed.expr
      else:
          expr = mixed
      if isinstance(expr, sa.orm.attributes.InstrumentedAttribute):
          return expr.parent.class_
      elif isinstance(expr, sa.Column):
          return expr.table
      elif isinstance(expr, sa.sql.expression.Label):
          if mixed.entity_zero:
              return mixed.entity_zero
          else:
              return expr
      elif isinstance(expr, sa.orm.Mapper):
          return expr.class_
      elif isinstance(expr, AliasedInsp):
          return expr.entity
      return expr
  
  
  def get_query_entity_by_alias(query, alias):
      entities = get_query_entities(query)
  
      if not alias:
          return entities[0]
  
      for entity in entities:
          if isinstance(entity, sa.orm.util.AliasedClass):
              name = sa.inspect(entity).name
          else:
              name = get_mapper(entity).tables[0].name
  
          if name == alias:
              return entity
  
  
  def get_polymorphic_mappers(mixed):
      if isinstance(mixed, AliasedInsp):
          return mixed.with_polymorphic_mappers
      else:
          return mixed.polymorphic_map.values()
  
  
  def get_query_descriptor(query, entity, attr):
      if attr in query_labels(query):
          return attr
      else:
          entity = get_query_entity_by_alias(query, entity)
          if entity:
              descriptor = get_descriptor(entity, attr)
              if (
                  hasattr(descriptor, 'property') and
                  isinstance(descriptor.property, sa.orm.RelationshipProperty)
              ):
                  return
              return descriptor
  
  
  def get_descriptor(entity, attr):
      mapper = sa.inspect(entity)
  
      for key, descriptor in get_all_descriptors(mapper).items():
          if attr == key:
              prop = (
                  descriptor.property
                  if hasattr(descriptor, 'property')
                  else None
              )
              if isinstance(prop, ColumnProperty):
                  if isinstance(entity, sa.orm.util.AliasedClass):
                      for c in mapper.selectable.c:
                          if c.key == attr:
                              return c
                  else:
                      # If the property belongs to a class that uses
                      # polymorphic inheritance we have to take into account
                      # situations where the attribute exists in child class
                      # but not in parent class.
                      return getattr(prop.parent.class_, attr)
              else:
                  # Handle synonyms, relationship properties and hybrid
                  # properties
                  try:
                      return getattr(entity, attr)
                  except AttributeError:
                      pass
  
  
  def get_all_descriptors(expr):
      insp = sa.inspect(expr)
      polymorphic_mappers = get_polymorphic_mappers(insp)
      if polymorphic_mappers:
          attrs = dict(get_mapper(expr).all_orm_descriptors)
          for submapper in polymorphic_mappers:
              for key, descriptor in submapper.all_orm_descriptors.items():
                  if key not in attrs:
                      attrs[key] = descriptor
          return attrs
      return get_mapper(expr).all_orm_descriptors
  
  
  def get_hybrid_properties(model):
      """
      Returns a dictionary of hybrid property keys and hybrid properties for
      given SQLAlchemy declarative model / mapper.
  
  
      Consider the following model
  
      ::
  
  
          from sqlalchemy.ext.hybrid import hybrid_property
  
  
          class Category(Base):
              __tablename__ = 'category'
              id = sa.Column(sa.Integer, primary_key=True)
              name = sa.Column(sa.Unicode(255))
  
              @hybrid_property
              def lowercase_name(self):
                  return self.name.lower()
  
              @lowercase_name.expression
              def lowercase_name(cls):
                  return sa.func.lower(cls.name)
  
  
      You can now easily get a list of all hybrid property names
  
      ::
  
  
          from sqlalchemy_utils import get_hybrid_properties
  
  
          get_hybrid_properties(Category).keys()  # ['lowercase_name']
  
  
      .. versionchanged: 0.26.7
          This function now returns a dictionary instead of generator
  
      :param model: SQLAlchemy declarative model or mapper
      """
      return dict(
          (key, prop)
          for key, prop in sa.inspect(model).all_orm_descriptors.items()
          if isinstance(prop, hybrid_property)
      )
  
  
  def get_declarative_base(model):
      """
      Returns the declarative base for given model class.
  
      :param model: SQLAlchemy declarative model
      """
      for parent in model.__bases__:
          try:
              parent.metadata
              return get_declarative_base(parent)
          except AttributeError:
              pass
      return model
  
  
  def getdotattr(obj_or_class, dot_path, condition=None):
      """
      Allow dot-notated strings to be passed to `getattr`.
  
      ::
  
          getdotattr(SubSection, 'section.document')
  
          getdotattr(subsection, 'section.document')
  
  
      :param obj_or_class: Any object or class
      :param dot_path: Attribute path with dot mark as separator
      """
      last = obj_or_class
  
      for path in str(dot_path).split('.'):
          getter = attrgetter(path)
  
          if is_sequence(last):
              tmp = []
              for element in last:
                  value = getter(element)
                  if is_sequence(value):
                      tmp.extend(value)
                  else:
                      tmp.append(value)
              last = tmp
          elif isinstance(last, InstrumentedAttribute):
              last = getter(last.property.mapper.class_)
          elif last is None:
              return None
          else:
              last = getter(last)
          if condition is not None:
              if is_sequence(last):
                  last = [v for v in last if condition(v)]
              else:
                  if not condition(last):
                      return None
  
      return last
  
  
  def is_deleted(obj):
      return obj in sa.orm.object_session(obj).deleted
  
  
  def has_changes(obj, attrs=None, exclude=None):
      """
      Simple shortcut function for checking if given attributes of given
      declarative model object have changed during the session. Without
      parameters this checks if given object has any modificiations. Additionally
      exclude parameter can be given to check if given object has any changes
      in any attributes other than the ones given in exclude.
  
  
      ::
  
  
          from sqlalchemy_utils import has_changes
  
  
          user = User()
  
          has_changes(user, 'name')  # False
  
          user.name = u'someone'
  
          has_changes(user, 'name')  # True
  
          has_changes(user)  # True
  
  
      You can check multiple attributes as well.
      ::
  
  
          has_changes(user, ['age'])  # True
  
          has_changes(user, ['name', 'age'])  # True
  
  
      This function also supports excluding certain attributes.
  
      ::
  
          has_changes(user, exclude=['name'])  # False
  
          has_changes(user, exclude=['age'])  # True
  
      .. versionchanged: 0.26.6
          Added support for multiple attributes and exclude parameter.
  
      :param obj: SQLAlchemy declarative model object
      :param attrs: Names of the attributes
      :param exclude: Names of the attributes to exclude
      """
      if attrs:
          if isinstance(attrs, six.string_types):
              return (
                  sa.inspect(obj)
                  .attrs
                  .get(attrs)
                  .history
                  .has_changes()
              )
          else:
              return any(has_changes(obj, attr) for attr in attrs)
      else:
          if exclude is None:
              exclude = []
          return any(
              attr.history.has_changes()
              for key, attr in sa.inspect(obj).attrs.items()
              if key not in exclude
          )
  
  
  def is_loaded(obj, prop):
      """
      Return whether or not given property of given object has been loaded.
  
      ::
  
          class Article(Base):
              __tablename__ = 'article'
              id = sa.Column(sa.Integer, primary_key=True)
              name = sa.Column(sa.String)
              content = sa.orm.deferred(sa.Column(sa.String))
  
  
          article = session.query(Article).get(5)
  
          # name gets loaded since its not a deferred property
          assert is_loaded(article, 'name')
  
          # content has not yet been loaded since its a deferred property
          assert not is_loaded(article, 'content')
  
  
      .. versionadded: 0.27.8
  
      :param obj: SQLAlchemy declarative model object
      :param prop: Name of the property or InstrumentedAttribute
      """
      return not isinstance(
          getattr(sa.inspect(obj).attrs, prop).loaded_value,
          sa.util.langhelpers._symbol
      )
  
  
  def identity(obj_or_class):
      """
      Return the identity of given sqlalchemy declarative model class or instance
      as a tuple. This differs from obj._sa_instance_state.identity in a way that
      it always returns the identity even if object is still in transient state (
      new object that is not yet persisted into database). Also for classes it
      returns the identity attributes.
  
      ::
  
          from sqlalchemy import inspect
          from sqlalchemy_utils import identity
  
  
          user = User(name=u'John Matrix')
          session.add(user)
          identity(user)  # None
          inspect(user).identity  # None
  
          session.flush()  # User now has id but is still in transient state
  
          identity(user)  # (1,)
          inspect(user).identity  # None
  
          session.commit()
  
          identity(user)  # (1,)
          inspect(user).identity  # (1, )
  
  
      You can also use identity for classes::
  
  
          identity(User)  # (User.id, )
  
      .. versionadded: 0.21.0
  
      :param obj: SQLAlchemy declarative model object
      """
      return tuple(
          getattr(obj_or_class, column_key)
          for column_key in get_primary_keys(obj_or_class).keys()
      )
  
  
  def naturally_equivalent(obj, obj2):
      """
      Returns whether or not two given SQLAlchemy declarative instances are
      naturally equivalent (all their non primary key properties are equivalent).
  
  
      ::
  
          from sqlalchemy_utils import naturally_equivalent
  
  
          user = User(name=u'someone')
          user2 = User(name=u'someone')
  
          user == user2  # False
  
          naturally_equivalent(user, user2)  # True
  
  
      :param obj: SQLAlchemy declarative model object
      :param obj2: SQLAlchemy declarative model object to compare with `obj`
      """
      for column_key, column in sa.inspect(obj.__class__).columns.items():
          if column.primary_key:
              continue
  
          if not (getattr(obj, column_key) == getattr(obj2, column_key)):
              return False
      return True
  