gnome.persist.extend_colander

Extend colander’s basic types for serialization/deserialization of gnome specific types

Classes

LocalDateTime	A type representing a Python datetime.datetime object.
DefaultTuple	A Tuple subclass that provides defaults from child nodes.
NumpyFixedLen	A subclass of colander.Tuple that converts itself to a Tuple and
NumpyArray	A subclass of colander.List that converts itself to a more general
DatetimeValue2dArray	A subclass of colander.Sequence that converts itself to a numpy
DatetimeValue1dArray	A subclass of colander.Sequence that converts itself to a numpy
TimeDelta	Add a type to serialize/deserialize timedelta objects
OrderedCollectionType	A type which represents a variable-length sequence of nodes,

Module Contents

class gnome.persist.extend_colander.LocalDateTime(*args, **kwargs)

Bases: colander.DateTime

A type representing a Python datetime.datetime object.

This type serializes python datetime.datetime objects to a ISO8601 string format. The format includes the date, the time, and the timezone of the datetime.

The constructor accepts an argument named default_tzinfo which should be a Python tzinfo object. If default_tzinfo is not specified the default tzinfo will be equivalent to UTC (Zulu time). The default_tzinfo tzinfo object is used to convert ‘naive’ datetimes to a timezone-aware representation during serialization. If default_tzinfo is explicitly set to None then no default tzinfo will be applied to naive datetimes.

You can adjust the error message reported by this class by changing its err_template attribute in a subclass on an instance of this class. By default, the err_template attribute is the string Invalid date. This string is used as the interpolation subject of a dictionary composed of val and err. val and err are the unvalidatable value and the exception caused trying to convert the value, respectively. These may be used in an overridden err_template as ${val} and ${err} respectively as necessary, e.g. _('${val} cannot be parsed as an iso8601 date: ${err}').

For convenience, this type is also willing to coerce datetime.date objects to a DateTime ISO string representation during serialization. It does so by using midnight of the day as the time, and uses the default_tzinfo to give the serialization a timezone.

Likewise, for convenience, during deserialization, this type will convert YYYY-MM-DD ISO8601 values to a datetime object. It does so by using midnight of the day as the time, and uses the default_tzinfo to give the serialization a timezone.

If the colander.null value is passed to the serialize method of this class, the colander.null value will be returned.

The subnodes of the colander.SchemaNode that wraps this type are ignored.

strip_timezone(_datetime)

serialize(node, appstruct)

Serialize a DateTime object

returns an iso formatted string

deserialize(node, cstruct)

class gnome.persist.extend_colander.DefaultTuple

Bases: colander.Tuple

A Tuple subclass that provides defaults from child nodes.

Required because Tuple returns colander.null by default when appstruct is not provided, instead of creating a Tuple of default values.

serialize(node, appstruct)

class gnome.persist.extend_colander.NumpyFixedLen

Bases: colander.Tuple

A subclass of colander.Tuple that converts itself to a Tuple and back to a numpy array. This is used to define schemas for Numpy arrays that have a fixed size like WorldPoint, 3D velocity of SimpleMover.

serialize(node, appstruct)

Serialize a fixed length numpy array

deserialize(node, cstruct)

class gnome.persist.extend_colander.NumpyArray

Bases: colander.List

A subclass of colander.List that converts itself to a more general numpy array of greater than length 1.

serialize(node, appstruct)

Serialize a numpy array

deserialize(node, cstruct)

class gnome.persist.extend_colander.DatetimeValue2dArray(accept_scalar=False)

Bases: colander.Sequence

A subclass of colander.Sequence that converts itself to a numpy array using gnome.basic_types.datetime_value_2d as the data type.

todo: serialize/deserialize must happen for each element - not very

efficient.

serialize(node, appstruct)

Serialize a 2D Datetime value array

deserialize(node, cstruct)

Along with the normal node and cstruct arguments, this method accepts an additional optional keyword argument: accept_scalar. This keyword argument can be used to override the constructor value of the same name.

If accept_scalar is True and the cstruct does not have an __iter__ method or is a mapping type, the value will be turned into a single element list.

If accept_scalar is False and the cstruct does not have an __iter__ method or is a mapping type, an colander.Invalid error will be raised during serialization and deserialization.

The default of accept_scalar is None, which means respect the default accept_scalar value attached to this instance via its constructor.

class gnome.persist.extend_colander.DatetimeValue1dArray(accept_scalar=False)

Bases: colander.Sequence

A subclass of colander.Sequence that converts itself to a numpy array using gnome.basic_types.datetime_value_2d as the data type.

serialize(node, appstruct)

Along with the normal node and appstruct arguments, this method accepts an additional optional keyword argument: accept_scalar. This keyword argument can be used to override the constructor value of the same name.

If accept_scalar is True and the appstruct does not have an __iter__ method or is a mapping type, the value will be turned into a single element list.

If accept_scalar is False and the appstruct does not have an __iter__ method or is a mapping type, an colander.Invalid error will be raised during serialization and deserialization.

The default of accept_scalar is None, which means respect the default accept_scalar value attached to this instance via its constructor.

deserialize(node, cstruct)

Along with the normal node and cstruct arguments, this method accepts an additional optional keyword argument: accept_scalar. This keyword argument can be used to override the constructor value of the same name.

If accept_scalar is True and the cstruct does not have an __iter__ method or is a mapping type, the value will be turned into a single element list.

If accept_scalar is False and the cstruct does not have an __iter__ method or is a mapping type, an colander.Invalid error will be raised during serialization and deserialization.

The default of accept_scalar is None, which means respect the default accept_scalar value attached to this instance via its constructor.

class gnome.persist.extend_colander.TimeDelta

Bases: colander.Float

Add a type to serialize/deserialize timedelta objects

serialize(node, appstruct)

deserialize(*args, **kwargs)

class gnome.persist.extend_colander.OrderedCollectionType(accept_scalar=False)

Bases: colander.Sequence

A type which represents a variable-length sequence of nodes, all of which must be of the same type.

The type of the first subnode of the colander.SchemaNode that wraps this type is considered the sequence type.

The optional accept_scalar argument to this type’s constructor indicates what should happen if the value found during serialization or deserialization does not have an __iter__ method or is a mapping type.

If accept_scalar is True and the value does not have an __iter__ method or is a mapping type, the value will be turned into a single element list.

If accept_scalar is False and the value does not have an __iter__ method or is a mapping type, an colander.Invalid error will be raised during serialization and deserialization.

The default value of accept_scalar is False.

If the colander.null value is passed to the serialize method of this class, the colander.null value is returned.