Python sqlalchemy.types.TypeDecorator() Examples

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Given an operator and value, gives the type a chance
        to return a type which the value should be coerced into.

        The default behavior here is conservative; if the right-hand
        side is already coerced into a SQL type based on its
        Python type, it is usually left alone.

        End-user functionality extension here should generally be via
        :class:`.TypeDecorator`, which provides more liberal behavior in that
        it defaults to coercing the other side of the expression into this
        type, thus applying special Python conversions above and beyond those
        needed by the DBAPI to both ides. It also provides the public method
        :meth:`.TypeDecorator.coerce_compared_value` which is intended for
        end-user customization of this behavior.

        """
        _coerced_type = _resolve_value_to_type(value)
        if _coerced_type is NULLTYPE or _coerced_type._type_affinity \
                is self._type_affinity:
            return self
        else:
            return _coerced_type 

def type_engine(self, dialect):
        """Return a dialect-specific :class:`.TypeEngine` instance
        for this :class:`.TypeDecorator`.

        In most cases this returns a dialect-adapted form of
        the :class:`.TypeEngine` type represented by ``self.impl``.
        Makes usage of :meth:`dialect_impl` but also traverses
        into wrapped :class:`.TypeDecorator` instances.
        Behavior can be customized here by overriding
        :meth:`load_dialect_impl`.

        """
        adapted = dialect.type_descriptor(self)
        if not isinstance(adapted, type(self)):
            return adapted
        elif isinstance(self.impl, TypeDecorator):
            return self.impl.type_engine(dialect)
        else:
            return self.load_dialect_impl(dialect) 

def _gen_dialect_impl(self, dialect):
        """
        #todo
        """
        adapted = dialect.type_descriptor(self)
        if adapted is not self:
            return adapted

        # otherwise adapt the impl type, link
        # to a copy of this TypeDecorator and return
        # that.
        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
        tt = self.copy()
        if not isinstance(tt, self.__class__):
            raise AssertionError('Type object %s does not properly '
                                 'implement the copy() method, it must '
                                 'return an object of type %s' %
                                 (self, self.__class__))
        tt.impl = typedesc
        return tt 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Default behavior for :class:`.UserDefinedType` is the
        same as that of :class:`.TypeDecorator`; by default it returns
        ``self``, assuming the compared value should be coerced into
        the same type as this one.  See
        :meth:`.TypeDecorator.coerce_compared_value` for more detail.

        .. versionchanged:: 0.8 :meth:`.UserDefinedType.coerce_compared_value`
           now returns ``self`` by default, rather than falling onto the
           more fundamental behavior of
           :meth:`.TypeEngine.coerce_compared_value`.

        """

        return self 

def type_engine(self, dialect):
        """Return a dialect-specific :class:`.TypeEngine` instance
        for this :class:`.TypeDecorator`.

        In most cases this returns a dialect-adapted form of
        the :class:`.TypeEngine` type represented by ``self.impl``.
        Makes usage of :meth:`dialect_impl` but also traverses
        into wrapped :class:`.TypeDecorator` instances.
        Behavior can be customized here by overriding
        :meth:`load_dialect_impl`.

        """
        adapted = dialect.type_descriptor(self)
        if not isinstance(adapted, type(self)):
            return adapted
        elif isinstance(self.impl, TypeDecorator):
            return self.impl.type_engine(dialect)
        else:
            return self.load_dialect_impl(dialect) 

def _gen_dialect_impl(self, dialect):
        """
        #todo
        """
        adapted = dialect.type_descriptor(self)
        if adapted is not self:
            return adapted

        # otherwise adapt the impl type, link
        # to a copy of this TypeDecorator and return
        # that.
        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
        tt = self.copy()
        if not isinstance(tt, self.__class__):
            raise AssertionError('Type object %s does not properly '
                                 'implement the copy() method, it must '
                                 'return an object of type %s' %
                                 (self, self.__class__))
        tt.impl = typedesc
        return tt 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Given an operator and value, gives the type a chance
        to return a type which the value should be coerced into.

        The default behavior here is conservative; if the right-hand
        side is already coerced into a SQL type based on its
        Python type, it is usually left alone.

        End-user functionality extension here should generally be via
        :class:`.TypeDecorator`, which provides more liberal behavior in that
        it defaults to coercing the other side of the expression into this
        type, thus applying special Python conversions above and beyond those
        needed by the DBAPI to both ides. It also provides the public method
        :meth:`.TypeDecorator.coerce_compared_value` which is intended for
        end-user customization of this behavior.

        """
        _coerced_type = _type_map.get(type(value), NULLTYPE)
        if _coerced_type is NULLTYPE or _coerced_type._type_affinity \
                is self._type_affinity:
            return self
        else:
            return _coerced_type 

def __init__(self, *args, **kwargs):
        """Construct a :class:`.TypeDecorator`.

        Arguments sent here are passed to the constructor
        of the class assigned to the ``impl`` class level attribute,
        assuming the ``impl`` is a callable, and the resulting
        object is assigned to the ``self.impl`` instance attribute
        (thus overriding the class attribute of the same name).

        If the class level ``impl`` is not a callable (the unusual case),
        it will be assigned to the same instance attribute 'as-is',
        ignoring those arguments passed to the constructor.

        Subclasses can override this to customize the generation
        of ``self.impl`` entirely.

        """

        if not hasattr(self.__class__, 'impl'):
            raise AssertionError("TypeDecorator implementations "
                                 "require a class-level variable "
                                 "'impl' which refers to the class of "
                                 "type being decorated")
        self.impl = to_instance(self.__class__.impl, *args, **kwargs) 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Default behavior for :class:`.UserDefinedType` is the
        same as that of :class:`.TypeDecorator`; by default it returns
        ``self``, assuming the compared value should be coerced into
        the same type as this one.  See
        :meth:`.TypeDecorator.coerce_compared_value` for more detail.

        .. versionchanged:: 0.8 :meth:`.UserDefinedType.coerce_compared_value`
           now returns ``self`` by default, rather than falling onto the
           more fundamental behavior of
           :meth:`.TypeEngine.coerce_compared_value`.

        """

        return self 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Given an operator and value, gives the type a chance
        to return a type which the value should be coerced into.

        The default behavior here is conservative; if the right-hand
        side is already coerced into a SQL type based on its
        Python type, it is usually left alone.

        End-user functionality extension here should generally be via
        :class:`.TypeDecorator`, which provides more liberal behavior in that
        it defaults to coercing the other side of the expression into this
        type, thus applying special Python conversions above and beyond those
        needed by the DBAPI to both ides. It also provides the public method
        :meth:`.TypeDecorator.coerce_compared_value` which is intended for
        end-user customization of this behavior.

        """
        _coerced_type = _type_map.get(type(value), NULLTYPE)
        if _coerced_type is NULLTYPE or _coerced_type._type_affinity \
                is self._type_affinity:
            return self
        else:
            return _coerced_type 

def __init__(self, *args, **kwargs):
        """Construct a :class:`.TypeDecorator`.

        Arguments sent here are passed to the constructor
        of the class assigned to the ``impl`` class level attribute,
        assuming the ``impl`` is a callable, and the resulting
        object is assigned to the ``self.impl`` instance attribute
        (thus overriding the class attribute of the same name).

        If the class level ``impl`` is not a callable (the unusual case),
        it will be assigned to the same instance attribute 'as-is',
        ignoring those arguments passed to the constructor.

        Subclasses can override this to customize the generation
        of ``self.impl`` entirely.

        """

        if not hasattr(self.__class__, 'impl'):
            raise AssertionError("TypeDecorator implementations "
                                 "require a class-level variable "
                                 "'impl' which refers to the class of "
                                 "type being decorated")
        self.impl = to_instance(self.__class__.impl, *args, **kwargs) 

def __init__(self, *args, **kwargs):
        """Construct a :class:`.TypeDecorator`.

        Arguments sent here are passed to the constructor
        of the class assigned to the ``impl`` class level attribute,
        assuming the ``impl`` is a callable, and the resulting
        object is assigned to the ``self.impl`` instance attribute
        (thus overriding the class attribute of the same name).

        If the class level ``impl`` is not a callable (the unusual case),
        it will be assigned to the same instance attribute 'as-is',
        ignoring those arguments passed to the constructor.

        Subclasses can override this to customize the generation
        of ``self.impl`` entirely.

        """

        if not hasattr(self.__class__, 'impl'):
            raise AssertionError("TypeDecorator implementations "
                                 "require a class-level variable "
                                 "'impl' which refers to the class of "
                                 "type being decorated")
        self.impl = to_instance(self.__class__.impl, *args, **kwargs) 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Default behavior for :class:`.UserDefinedType` is the
        same as that of :class:`.TypeDecorator`; by default it returns
        ``self``, assuming the compared value should be coerced into
        the same type as this one.  See
        :meth:`.TypeDecorator.coerce_compared_value` for more detail.

        .. versionchanged:: 0.8 :meth:`.UserDefinedType.coerce_compared_value`
           now returns ``self`` by default, rather than falling onto the
           more fundamental behavior of
           :meth:`.TypeEngine.coerce_compared_value`.

        """

        return self 

def type_engine(self, dialect):
        """Return a dialect-specific :class:`.TypeEngine` instance
        for this :class:`.TypeDecorator`.

        In most cases this returns a dialect-adapted form of
        the :class:`.TypeEngine` type represented by ``self.impl``.
        Makes usage of :meth:`dialect_impl` but also traverses
        into wrapped :class:`.TypeDecorator` instances.
        Behavior can be customized here by overriding
        :meth:`load_dialect_impl`.

        """
        adapted = dialect.type_descriptor(self)
        if not isinstance(adapted, type(self)):
            return adapted
        elif isinstance(self.impl, TypeDecorator):
            return self.impl.type_engine(dialect)
        else:
            return self.load_dialect_impl(dialect) 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Given an operator and value, gives the type a chance
        to return a type which the value should be coerced into.

        The default behavior here is conservative; if the right-hand
        side is already coerced into a SQL type based on its
        Python type, it is usually left alone.

        End-user functionality extension here should generally be via
        :class:`.TypeDecorator`, which provides more liberal behavior in that
        it defaults to coercing the other side of the expression into this
        type, thus applying special Python conversions above and beyond those
        needed by the DBAPI to both ides. It also provides the public method
        :meth:`.TypeDecorator.coerce_compared_value` which is intended for
        end-user customization of this behavior.

        """
        _coerced_type = _type_map.get(type(value), NULLTYPE)
        if _coerced_type is NULLTYPE or _coerced_type._type_affinity \
                is self._type_affinity:
            return self
        else:
            return _coerced_type 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Default behavior for :class:`.UserDefinedType` is the
        same as that of :class:`.TypeDecorator`; by default it returns
        ``self``, assuming the compared value should be coerced into
        the same type as this one.  See
        :meth:`.TypeDecorator.coerce_compared_value` for more detail.

        .. versionchanged:: 0.8 :meth:`.UserDefinedType.coerce_compared_value`
           now returns ``self`` by default, rather than falling onto the
           more fundamental behavior of
           :meth:`.TypeEngine.coerce_compared_value`.

        """

        return self 

def __init__(self, *args, **kwargs):
        """Construct a :class:`.TypeDecorator`.

        Arguments sent here are passed to the constructor
        of the class assigned to the ``impl`` class level attribute,
        assuming the ``impl`` is a callable, and the resulting
        object is assigned to the ``self.impl`` instance attribute
        (thus overriding the class attribute of the same name).

        If the class level ``impl`` is not a callable (the unusual case),
        it will be assigned to the same instance attribute 'as-is',
        ignoring those arguments passed to the constructor.

        Subclasses can override this to customize the generation
        of ``self.impl`` entirely.

        """

        if not hasattr(self.__class__, 'impl'):
            raise AssertionError("TypeDecorator implementations "
                                 "require a class-level variable "
                                 "'impl' which refers to the class of "
                                 "type being decorated")
        self.impl = to_instance(self.__class__.impl, *args, **kwargs) 

def _gen_dialect_impl(self, dialect):
        """
        #todo
        """
        adapted = dialect.type_descriptor(self)
        if adapted is not self:
            return adapted

        # otherwise adapt the impl type, link
        # to a copy of this TypeDecorator and return
        # that.
        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
        tt = self.copy()
        if not isinstance(tt, self.__class__):
            raise AssertionError('Type object %s does not properly '
                                 'implement the copy() method, it must '
                                 'return an object of type %s' %
                                 (self, self.__class__))
        tt.impl = typedesc
        return tt 

def type_engine(self, dialect):
        """Return a dialect-specific :class:`.TypeEngine` instance
        for this :class:`.TypeDecorator`.

        In most cases this returns a dialect-adapted form of
        the :class:`.TypeEngine` type represented by ``self.impl``.
        Makes usage of :meth:`dialect_impl` but also traverses
        into wrapped :class:`.TypeDecorator` instances.
        Behavior can be customized here by overriding
        :meth:`load_dialect_impl`.

        """
        adapted = dialect.type_descriptor(self)
        if not isinstance(adapted, type(self)):
            return adapted
        elif isinstance(self.impl, TypeDecorator):
            return self.impl.type_engine(dialect)
        else:
            return self.load_dialect_impl(dialect) 

def type_engine(self, dialect):
        """Return a dialect-specific :class:`.TypeEngine` instance
        for this :class:`.TypeDecorator`.

        In most cases this returns a dialect-adapted form of
        the :class:`.TypeEngine` type represented by ``self.impl``.
        Makes usage of :meth:`dialect_impl` but also traverses
        into wrapped :class:`.TypeDecorator` instances.
        Behavior can be customized here by overriding
        :meth:`load_dialect_impl`.

        """
        adapted = dialect.type_descriptor(self)
        if not isinstance(adapted, type(self)):
            return adapted
        elif isinstance(self.impl, TypeDecorator):
            return self.impl.type_engine(dialect)
        else:
            return self.load_dialect_impl(dialect) 

def _gen_dialect_impl(self, dialect):
        """
        #todo
        """
        adapted = dialect.type_descriptor(self)
        if adapted is not self:
            return adapted

        # otherwise adapt the impl type, link
        # to a copy of this TypeDecorator and return
        # that.
        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
        tt = self.copy()
        if not isinstance(tt, self.__class__):
            raise AssertionError('Type object %s does not properly '
                                 'implement the copy() method, it must '
                                 'return an object of type %s' %
                                 (self, self.__class__))
        tt.impl = typedesc
        return tt 

def __init__(self, *args, **kwargs):
        """Construct a :class:`.TypeDecorator`.

        Arguments sent here are passed to the constructor
        of the class assigned to the ``impl`` class level attribute,
        assuming the ``impl`` is a callable, and the resulting
        object is assigned to the ``self.impl`` instance attribute
        (thus overriding the class attribute of the same name).

        If the class level ``impl`` is not a callable (the unusual case),
        it will be assigned to the same instance attribute 'as-is',
        ignoring those arguments passed to the constructor.

        Subclasses can override this to customize the generation
        of ``self.impl`` entirely.

        """

        if not hasattr(self.__class__, 'impl'):
            raise AssertionError("TypeDecorator implementations "
                                 "require a class-level variable "
                                 "'impl' which refers to the class of "
                                 "type being decorated")
        self.impl = to_instance(self.__class__.impl, *args, **kwargs) 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Default behavior for :class:`.UserDefinedType` is the
        same as that of :class:`.TypeDecorator`; by default it returns
        ``self``, assuming the compared value should be coerced into
        the same type as this one.  See
        :meth:`.TypeDecorator.coerce_compared_value` for more detail.

        .. versionchanged:: 0.8 :meth:`.UserDefinedType.coerce_compared_value`
           now returns ``self`` by default, rather than falling onto the
           more fundamental behavior of
           :meth:`.TypeEngine.coerce_compared_value`.

        """

        return self 

def coerce_compared_value(self, op, value):
        """Suggest a type for a 'coerced' Python value in an expression.

        Given an operator and value, gives the type a chance
        to return a type which the value should be coerced into.

        The default behavior here is conservative; if the right-hand
        side is already coerced into a SQL type based on its
        Python type, it is usually left alone.

        End-user functionality extension here should generally be via
        :class:`.TypeDecorator`, which provides more liberal behavior in that
        it defaults to coercing the other side of the expression into this
        type, thus applying special Python conversions above and beyond those
        needed by the DBAPI to both ides. It also provides the public method
        :meth:`.TypeDecorator.coerce_compared_value` which is intended for
        end-user customization of this behavior.

        """
        _coerced_type = _resolve_value_to_type(value)
        if _coerced_type is NULLTYPE or _coerced_type._type_affinity \
                is self._type_affinity:
            return self
        else:
            return _coerced_type 

def _makeType(impl_):
    from sqlalchemy.types import TypeDecorator

    class Choice(TypeDecorator):
        impl = impl_

        def __init__(self, choices, **kw):
            self.choices = dict(choices)
            super(Choice, self).__init__(**kw)

        def process_bind_param(self, value, dialect):
            return [k for k, v in self.choices.iteritems() if v == value][0]

        def process_result_value(self, value, dialect):
            return self.choices[value]

    return Choice 

def _gen_dialect_impl(self, dialect):
        """
        #todo
        """
        adapted = dialect.type_descriptor(self)
        if adapted is not self:
            return adapted

        # otherwise adapt the impl type, link
        # to a copy of this TypeDecorator and return
        # that.
        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
        tt = self.copy()
        if not isinstance(tt, self.__class__):
            raise AssertionError('Type object %s does not properly '
                                 'implement the copy() method, it must '
                                 'return an object of type %s' %
                                 (self, self.__class__))
        tt.impl = typedesc
        return tt 

def _has_result_processor(self):
        """memoized boolean, check if process_result_value is implemented.

        Allows the base process_result_value to raise
        NotImplementedError without needing to tests an expensive
        exception throw.

        """
        return self.__class__.process_result_value.__code__ \
            is not TypeDecorator.process_result_value.__code__ 

def _set_parent(self, column):
        """Support SchemaEventTarget"""

        super(TypeDecorator, self)._set_parent(column)

        if isinstance(self.impl, SchemaEventTarget):
            self.impl._set_parent(column) 

def load_dialect_impl(self, dialect):
        """Return a :class:`.TypeEngine` object corresponding to a dialect.

        This is an end-user override hook that can be used to provide
        differing types depending on the given dialect.  It is used
        by the :class:`.TypeDecorator` implementation of :meth:`type_engine`
        to help determine what type should ultimately be returned
        for a given :class:`.TypeDecorator`.

        By default returns ``self.impl``.

        """
        return self.impl 

def _set_parent_with_dispatch(self, parent):
        """Support SchemaEventTarget"""

        super(TypeDecorator, self)._set_parent_with_dispatch(parent)

        if isinstance(self.impl, SchemaEventTarget):
            self.impl._set_parent_with_dispatch(parent)