"""Field classes for various types of data."""
import collections
import copy
import datetime as dt
import numbers
import uuid
import ipaddress
import decimal
import math
import typing
import warnings
from collections.abc import Mapping as _Mapping
from marshmallow import validate, utils, class_registry, types
from marshmallow.base import FieldABC, SchemaABC
from marshmallow.utils import (
is_collection,
missing as missing_,
resolve_field_instance,
is_aware,
)
from marshmallow.exceptions import (
ValidationError,
StringNotCollectionError,
FieldInstanceResolutionError,
)
from marshmallow.validate import And, Length
from marshmallow.warnings import RemovedInMarshmallow4Warning
__all__ = [
"Field",
"Raw",
"Nested",
"Mapping",
"Dict",
"List",
"Tuple",
"String",
"UUID",
"Number",
"Integer",
"Decimal",
"Boolean",
"Float",
"DateTime",
"NaiveDateTime",
"AwareDateTime",
"Time",
"Date",
"TimeDelta",
"Url",
"URL",
"Email",
"IP",
"IPv4",
"IPv6",
"IPInterface",
"IPv4Interface",
"IPv6Interface",
"Method",
"Function",
"Str",
"Bool",
"Int",
"Constant",
"Pluck",
]
_T = typing.TypeVar("_T")
class Field(FieldABC):
"""Basic field from which other fields should extend. It applies no
formatting by default, and should only be used in cases where
data does not need to be formatted before being serialized or deserialized.
On error, the name of the field will be returned.
:param default: If set, this value will be used during serialization if the input value
is missing. If not set, the field will be excluded from the serialized output if the
input value is missing. May be a value or a callable.
:param missing: Default deserialization value for the field if the field is not
found in the input data. May be a value or a callable.
:param data_key: The name of the dict key in the external representation, i.e.
the input of `load` and the output of `dump`.
If `None`, the key will match the name of the field.
:param attribute: The name of the attribute to get the value from when serializing.
If `None`, assumes the attribute has the same name as the field.
Note: This should only be used for very specific use cases such as
outputting multiple fields for a single attribute. In most cases,
you should use ``data_key`` instead.
:param validate: Validator or collection of validators that are called
during deserialization. Validator takes a field's input value as
its only parameter and returns a boolean.
If it returns `False`, an :exc:`ValidationError` is raised.
:param required: Raise a :exc:`ValidationError` if the field value
is not supplied during deserialization.
:param allow_none: Set this to `True` if `None` should be considered a valid value during
validation/deserialization. If ``missing=None`` and ``allow_none`` is unset,
will default to ``True``. Otherwise, the default is ``False``.
:param load_only: If `True` skip this field during serialization, otherwise
its value will be present in the serialized data.
:param dump_only: If `True` skip this field during deserialization, otherwise
its value will be present in the deserialized object. In the context of an
HTTP API, this effectively marks the field as "read-only".
:param dict error_messages: Overrides for `Field.default_error_messages`.
:param metadata: Extra information to be stored as field metadata.
.. versionchanged:: 2.0.0
Removed `error` parameter. Use ``error_messages`` instead.
.. versionchanged:: 2.0.0
Added `allow_none` parameter, which makes validation/deserialization of `None`
consistent across fields.
.. versionchanged:: 2.0.0
Added `load_only` and `dump_only` parameters, which allow field skipping
during the (de)serialization process.
.. versionchanged:: 2.0.0
Added `missing` parameter, which indicates the value for a field if the field
is not found during deserialization.
.. versionchanged:: 2.0.0
``default`` value is only used if explicitly set. Otherwise, missing values
inputs are excluded from serialized output.
.. versionchanged:: 3.0.0b8
Add ``data_key`` parameter for the specifying the key in the input and
output data. This parameter replaced both ``load_from`` and ``dump_to``.
"""
# Some fields, such as Method fields and Function fields, are not expected
# to exist as attributes on the objects to serialize. Set this to False
# for those fields
_CHECK_ATTRIBUTE = True
_creation_index = 0 # Used for sorting
#: Default error messages for various kinds of errors. The keys in this dictionary
#: are passed to `Field.make_error`. The values are error messages passed to
#: :exc:`marshmallow.exceptions.ValidationError`.
default_error_messages = {
"required": "Missing data for required field.",
"null": "Field may not be null.",
"validator_failed": "Invalid value.",
}
def __init__(
self,
*,
default: typing.Any = missing_,
missing: typing.Any = missing_,
data_key: typing.Optional[str] = None,
attribute: typing.Optional[str] = None,
validate: typing.Optional[
typing.Union[
typing.Callable[[typing.Any], typing.Any],
typing.Iterable[typing.Callable[[typing.Any], typing.Any]],
]
] = None,
required: bool = False,
allow_none: typing.Optional[bool] = None,
load_only: bool = False,
dump_only: bool = False,
error_messages: typing.Optional[typing.Dict[str, str]] = None,
metadata: typing.Optional[typing.Mapping[str, typing.Any]] = None,
**additional_metadata
) -> None:
self.default = default
self.attribute = attribute
self.data_key = data_key
self.validate = validate
if validate is None:
self.validators = []
elif callable(validate):
self.validators = [validate]
elif utils.is_iterable_but_not_string(validate):
self.validators = list(validate)
else:
raise ValueError(
"The 'validate' parameter must be a callable "
"or a collection of callables."
)
# If allow_none is None and missing is None
# None should be considered valid by default
self.allow_none = missing is None if allow_none is None else allow_none
self.load_only = load_only
self.dump_only = dump_only
if required is True and missing is not missing_:
raise ValueError("'missing' must not be set for required fields.")
self.required = required
self.missing = missing
metadata = metadata or {}
self.metadata = {**metadata, **additional_metadata}
if additional_metadata:
warnings.warn(
"Passing field metadata as a keyword arg is deprecated. Use the "
"explicit `metadata=...` argument instead.",
RemovedInMarshmallow4Warning,
)
self._creation_index = Field._creation_index
Field._creation_index += 1
# Collect default error message from self and parent classes
messages = {} # type: typing.Dict[str, str]
for cls in reversed(self.__class__.__mro__):
messages.update(getattr(cls, "default_error_messages", {}))
messages.update(error_messages or {})
self.error_messages = messages
def __repr__(self) -> str:
return (
"<fields.{ClassName}(default={self.default!r}, "
"attribute={self.attribute!r}, "
"validate={self.validate}, required={self.required}, "
"load_only={self.load_only}, dump_only={self.dump_only}, "
"missing={self.missing}, allow_none={self.allow_none}, "
"error_messages={self.error_messages})>".format(
ClassName=self.__class__.__name__, self=self
)
)
def __deepcopy__(self, memo):
return copy.copy(self)
def get_value(self, obj, attr, accessor=None, default=missing_):
"""Return the value for a given key from an object.
:param object obj: The object to get the value from.
:param str attr: The attribute/key in `obj` to get the value from.
:param callable accessor: A callable used to retrieve the value of `attr` from
the object `obj`. Defaults to `marshmallow.utils.get_value`.
"""
accessor_func = accessor or utils.get_value
check_key = attr if self.attribute is None else self.attribute
return accessor_func(obj, check_key, default)
def _validate(self, value):
"""Perform validation on ``value``. Raise a :exc:`ValidationError` if validation
does not succeed.
"""
self._validate_all(value)
@property
def _validate_all(self):
return And(*self.validators, error=self.error_messages["validator_failed"])
def make_error(self, key: str, **kwargs) -> ValidationError:
"""Helper method to make a `ValidationError` with an error message
from ``self.error_messages``.
"""
try:
msg = self.error_messages[key]
except KeyError as error:
class_name = self.__class__.__name__
message = (
"ValidationError raised by `{class_name}`, but error key `{key}` does "
"not exist in the `error_messages` dictionary."
).format(class_name=class_name, key=key)
raise AssertionError(message) from error
if isinstance(msg, (str, bytes)):
msg = msg.format(**kwargs)
return ValidationError(msg)
def fail(self, key: str, **kwargs):
"""Helper method that raises a `ValidationError` with an error message
from ``self.error_messages``.
.. deprecated:: 3.0.0
Use `make_error <marshmallow.fields.Field.make_error>` instead.
"""
warnings.warn(
'`Field.fail` is deprecated. Use `raise self.make_error("{}", ...)` instead.'.format(
key
),
RemovedInMarshmallow4Warning,
)
raise self.make_error(key=key, **kwargs)
def _validate_missing(self, value):
"""Validate missing values. Raise a :exc:`ValidationError` if
`value` should be considered missing.
"""
if value is missing_ and self.required:
raise self.make_error("required")
if value is None and not self.allow_none:
raise self.make_error("null")
def serialize(
self,
attr: str,
obj: typing.Any,
accessor: typing.Optional[
typing.Callable[[typing.Any, str, typing.Any], typing.Any]
] = None,
**kwargs
):
"""Pulls the value for the given key from the object, applies the
field's formatting and returns the result.
:param attr: The attribute/key to get from the object.
:param obj: The object to access the attribute/key from.
:param accessor: Function used to access values from ``obj``.
:param kwargs: Field-specific keyword arguments.
"""
if self._CHECK_ATTRIBUTE:
value = self.get_value(obj, attr, accessor=accessor)
if value is missing_:
default = self.default
value = default() if callable(default) else default
if value is missing_:
return value
else:
value = None
return self._serialize(value, attr, obj, **kwargs)
def deserialize(
self,
value: typing.Any,
attr: typing.Optional[str] = None,
data: typing.Optional[typing.Mapping[str, typing.Any]] = None,
**kwargs
):
"""Deserialize ``value``.
:param value: The value to deserialize.
:param attr: The attribute/key in `data` to deserialize.
:param data: The raw input data passed to `Schema.load`.
:param kwargs: Field-specific keyword arguments.
:raise ValidationError: If an invalid value is passed or if a required value
is missing.
"""
# Validate required fields, deserialize, then validate
# deserialized value
self._validate_missing(value)
if value is missing_:
_miss = self.missing
return _miss() if callable(_miss) else _miss
if self.allow_none and value is None:
return None
output = self._deserialize(value, attr, data, **kwargs)
self._validate(output)
return output
# Methods for concrete classes to override.
def _bind_to_schema(self, field_name, schema):
"""Update field with values from its parent schema. Called by
:meth:`Schema._bind_field <marshmallow.Schema._bind_field>`.
:param str field_name: Field name set in schema.
:param Schema|Field schema: Parent object.
"""
self.parent = self.parent or schema
self.name = self.name or field_name
self.root = self.root or (
self.parent.root if isinstance(self.parent, FieldABC) else self.parent
)
def _serialize(self, value: typing.Any, attr: str, obj: typing.Any, **kwargs):
"""Serializes ``value`` to a basic Python datatype. Noop by default.
Concrete :class:`Field` classes should implement this method.
Example: ::
class TitleCase(Field):
def _serialize(self, value, attr, obj, **kwargs):
if not value:
return ''
return str(value).title()
:param value: The value to be serialized.
:param str attr: The attribute or key on the object to be serialized.
:param object obj: The object the value was pulled from.
:param dict kwargs: Field-specific keyword arguments.
:return: The serialized value
"""
return value
def _deserialize(
self,
value: typing.Any,
attr: typing.Optional[str],
data: typing.Optional[typing.Mapping[str, typing.Any]],
**kwargs
):
"""Deserialize value. Concrete :class:`Field` classes should implement this method.
:param value: The value to be deserialized.
:param attr: The attribute/key in `data` to be deserialized.
:param data: The raw input data passed to the `Schema.load`.
:param kwargs: Field-specific keyword arguments.
:raise ValidationError: In case of formatting or validation failure.
:return: The deserialized value.
.. versionchanged:: 2.0.0
Added ``attr`` and ``data`` parameters.
.. versionchanged:: 3.0.0
Added ``**kwargs`` to signature.
"""
return value
# Properties
@property
def context(self):
"""The context dictionary for the parent :class:`Schema`."""
return self.parent.context
class Raw(Field):
"""Field that applies no formatting."""
class Nested(Field):
"""Allows you to nest a :class:`Schema <marshmallow.Schema>`
inside a field.
Examples: ::
class ChildSchema(Schema):
id = fields.Str()
name = fields.Str()
# Use lambda functions when you need two-way nesting or self-nesting
parent = fields.Nested(lambda: ParentSchema(only=("id",)), dump_only=True)
siblings = fields.List(fields.Nested(lambda: ChildSchema(only=("id", "name"))))
class ParentSchema(Schema):
id = fields.Str()
children = fields.List(
fields.Nested(ChildSchema(only=("id", "parent", "siblings")))
)
spouse = fields.Nested(lambda: ParentSchema(only=("id",)))
When passing a `Schema <marshmallow.Schema>` instance as the first argument,
the instance's ``exclude``, ``only``, and ``many`` attributes will be respected.
Therefore, when passing the ``exclude``, ``only``, or ``many`` arguments to `fields.Nested`,
you should pass a `Schema <marshmallow.Schema>` class (not an instance) as the first argument.
::
# Yes
author = fields.Nested(UserSchema, only=('id', 'name'))
# No
author = fields.Nested(UserSchema(), only=('id', 'name'))
:param nested: `Schema` instance, class, class name (string), or callable that returns a `Schema` instance.
:param exclude: A list or tuple of fields to exclude.
:param only: A list or tuple of fields to marshal. If `None`, all fields are marshalled.
This parameter takes precedence over ``exclude``.
:param many: Whether the field is a collection of objects.
:param unknown: Whether to exclude, include, or raise an error for unknown
fields in the data. Use `EXCLUDE`, `INCLUDE` or `RAISE`.
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
#: Default error messages.
default_error_messages = {"type": "Invalid type."}
def __init__(
self,
nested: typing.Union[SchemaABC, type, str, typing.Callable[[], SchemaABC]],
*,
default: typing.Any = missing_,
only: typing.Optional[types.StrSequenceOrSet] = None,
exclude: types.StrSequenceOrSet = (),
many: bool = False,
unknown: typing.Optional[str] = None,
**kwargs
):
# Raise error if only or exclude is passed as string, not list of strings
if only is not None and not is_collection(only):
raise StringNotCollectionError('"only" should be a collection of strings.')
if not is_collection(exclude):
raise StringNotCollectionError(
'"exclude" should be a collection of strings.'
)
if nested == "self":
warnings.warn(
"Passing 'self' to `Nested` is deprecated. "
"Use `Nested(lambda: MySchema(...))` instead.",
RemovedInMarshmallow4Warning,
)
self.nested = nested
self.only = only
self.exclude = exclude
self.many = many
self.unknown = unknown
self._schema = None # Cached Schema instance
super().__init__(default=default, **kwargs)
@property
def schema(self):
"""The nested Schema object.
.. versionchanged:: 1.0.0
Renamed from `serializer` to `schema`.
"""
if not self._schema:
# Inherit context from parent.
context = getattr(self.parent, "context", {})
if callable(self.nested) and not isinstance(self.nested, type):
nested = self.nested()
else:
nested = self.nested
if isinstance(nested, SchemaABC):
self._schema = copy.copy(nested)
self._schema.context.update(context)
# Respect only and exclude passed from parent and re-initialize fields
set_class = self._schema.set_class
if self.only is not None:
if self._schema.only is not None:
original = self._schema.only
else: # only=None -> all fields
original = self._schema.fields.keys()
self._schema.only = set_class(self.only) & set_class(original)
if self.exclude:
original = self._schema.exclude
self._schema.exclude = set_class(self.exclude) | set_class(original)
self._schema._init_fields()
else:
if isinstance(nested, type) and issubclass(nested, SchemaABC):
schema_class = nested
elif not isinstance(nested, (str, bytes)):
raise ValueError(
"`Nested` fields must be passed a "
"`Schema`, not {}.".format(nested.__class__)
)
elif nested == "self":
schema_class = self.root.__class__
else:
schema_class = class_registry.get_class(nested)
self._schema = schema_class(
many=self.many,
only=self.only,
exclude=self.exclude,
context=context,
load_only=self._nested_normalized_option("load_only"),
dump_only=self._nested_normalized_option("dump_only"),
)
return self._schema
def _nested_normalized_option(self, option_name: str) -> typing.List[str]:
nested_field = "%s." % self.name
return [
field.split(nested_field, 1)[1]
for field in getattr(self.root, option_name, set())
if field.startswith(nested_field)
]
def _serialize(self, nested_obj, attr, obj, **kwargs):
# Load up the schema first. This allows a RegistryError to be raised
# if an invalid schema name was passed
schema = self.schema
if nested_obj is None:
return None
many = schema.many or self.many
return schema.dump(nested_obj, many=many)
def _test_collection(self, value):
many = self.schema.many or self.many
if many and not utils.is_collection(value):
raise self.make_error("type", input=value, type=value.__class__.__name__)
def _load(self, value, data, partial=None):
try:
valid_data = self.schema.load(value, unknown=self.unknown, partial=partial)
except ValidationError as error:
raise ValidationError(
error.messages, valid_data=error.valid_data
) from error
return valid_data
def _deserialize(self, value, attr, data, partial=None, **kwargs):
"""Same as :meth:`Field._deserialize` with additional ``partial`` argument.
:param bool|tuple partial: For nested schemas, the ``partial``
parameter passed to `Schema.load`.
.. versionchanged:: 3.0.0
Add ``partial`` parameter.
"""
self._test_collection(value)
return self._load(value, data, partial=partial)
class Pluck(Nested):
"""Allows you to replace nested data with one of the data's fields.
Example: ::
from marshmallow import Schema, fields
class ArtistSchema(Schema):
id = fields.Int()
name = fields.Str()
class AlbumSchema(Schema):
artist = fields.Pluck(ArtistSchema, 'id')
in_data = {'artist': 42}
loaded = AlbumSchema().load(in_data) # => {'artist': {'id': 42}}
dumped = AlbumSchema().dump(loaded) # => {'artist': 42}
:param Schema nested: The Schema class or class name (string)
to nest, or ``"self"`` to nest the :class:`Schema` within itself.
:param str field_name: The key to pluck a value from.
:param kwargs: The same keyword arguments that :class:`Nested` receives.
"""
def __init__(
self,
nested: typing.Union[SchemaABC, type, str, typing.Callable[[], SchemaABC]],
field_name: str,
**kwargs
):
super().__init__(nested, only=(field_name,), **kwargs)
self.field_name = field_name
@property
def _field_data_key(self):
only_field = self.schema.fields[self.field_name]
return only_field.data_key or self.field_name
def _serialize(self, nested_obj, attr, obj, **kwargs):
ret = super()._serialize(nested_obj, attr, obj, **kwargs)
if ret is None:
return None
if self.many:
return utils.pluck(ret, key=self._field_data_key)
return ret[self._field_data_key]
def _deserialize(self, value, attr, data, partial=None, **kwargs):
self._test_collection(value)
if self.many:
value = [{self._field_data_key: v} for v in value]
else:
value = {self._field_data_key: value}
return self._load(value, data, partial=partial)
class List(Field):
"""A list field, composed with another `Field` class or
instance.
Example: ::
numbers = fields.List(fields.Float())
:param cls_or_instance: A field class or instance.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionchanged:: 2.0.0
The ``allow_none`` parameter now applies to deserialization and
has the same semantics as the other fields.
.. versionchanged:: 3.0.0rc9
Does not serialize scalar values to single-item lists.
"""
#: Default error messages.
default_error_messages = {"invalid": "Not a valid list."}
def __init__(self, cls_or_instance: typing.Union[Field, type], **kwargs):
super().__init__(**kwargs)
try:
self.inner = resolve_field_instance(cls_or_instance)
except FieldInstanceResolutionError as error:
raise ValueError(
"The list elements must be a subclass or instance of "
"marshmallow.base.FieldABC."
) from error
if isinstance(self.inner, Nested):
self.only = self.inner.only
self.exclude = self.inner.exclude
def _bind_to_schema(self, field_name, schema):
super()._bind_to_schema(field_name, schema)
self.inner = copy.deepcopy(self.inner)
self.inner._bind_to_schema(field_name, self)
if isinstance(self.inner, Nested):
self.inner.only = self.only
self.inner.exclude = self.exclude
def _serialize(
self, value, attr, obj, **kwargs
) -> typing.Optional[typing.List[typing.Any]]:
if value is None:
return None
return [self.inner._serialize(each, attr, obj, **kwargs) for each in value]
def _deserialize(self, value, attr, data, **kwargs) -> typing.List[typing.Any]:
if not utils.is_collection(value):
raise self.make_error("invalid")
result = []
errors = {}
for idx, each in enumerate(value):
try:
result.append(self.inner.deserialize(each, **kwargs))
except ValidationError as error:
if error.valid_data is not None:
result.append(error.valid_data)
errors.update({idx: error.messages})
if errors:
raise ValidationError(errors, valid_data=result)
return result
class Tuple(Field):
"""A tuple field, composed of a fixed number of other `Field` classes or
instances
Example: ::
row = Tuple((fields.String(), fields.Integer(), fields.Float()))
.. note::
Because of the structured nature of `collections.namedtuple` and
`typing.NamedTuple`, using a Schema within a Nested field for them is
more appropriate than using a `Tuple` field.
:param Iterable[Field] tuple_fields: An iterable of field classes or
instances.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionadded:: 3.0.0rc4
"""
#: Default error messages.
default_error_messages = {"invalid": "Not a valid tuple."}
def __init__(self, tuple_fields, *args, **kwargs):
super().__init__(*args, **kwargs)
if not utils.is_collection(tuple_fields):
raise ValueError(
"tuple_fields must be an iterable of Field classes or " "instances."
)
try:
self.tuple_fields = [
resolve_field_instance(cls_or_instance)
for cls_or_instance in tuple_fields
]
except FieldInstanceResolutionError as error:
raise ValueError(
'Elements of "tuple_fields" must be subclasses or '
"instances of marshmallow.base.FieldABC."
) from error
self.validate_length = Length(equal=len(self.tuple_fields))
def _bind_to_schema(self, field_name, schema):
super()._bind_to_schema(field_name, schema)
new_tuple_fields = []
for field in self.tuple_fields:
field = copy.deepcopy(field)
field._bind_to_schema(field_name, self)
new_tuple_fields.append(field)
self.tuple_fields = new_tuple_fields
def _serialize(self, value, attr, obj, **kwargs) -> typing.Optional[typing.Tuple]:
if value is None:
return None
return tuple(
field._serialize(each, attr, obj, **kwargs)
for field, each in zip(self.tuple_fields, value)
)
def _deserialize(self, value, attr, data, **kwargs) -> typing.Tuple:
if not utils.is_collection(value):
raise self.make_error("invalid")
self.validate_length(value)
result = []
errors = {}
for idx, (field, each) in enumerate(zip(self.tuple_fields, value)):
try:
result.append(field.deserialize(each, **kwargs))
except ValidationError as error:
if error.valid_data is not None:
result.append(error.valid_data)
errors.update({idx: error.messages})
if errors:
raise ValidationError(errors, valid_data=result)
return tuple(result)
class String(Field):
"""A string field.
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
#: Default error messages.
default_error_messages = {
"invalid": "Not a valid string.",
"invalid_utf8": "Not a valid utf-8 string.",
}
def _serialize(self, value, attr, obj, **kwargs) -> typing.Optional[str]:
if value is None:
return None
return utils.ensure_text_type(value)
def _deserialize(self, value, attr, data, **kwargs) -> typing.Any:
if not isinstance(value, (str, bytes)):
raise self.make_error("invalid")
try:
return utils.ensure_text_type(value)
except UnicodeDecodeError as error:
raise self.make_error("invalid_utf8") from error
class UUID(String):
"""A UUID field."""
#: Default error messages.
default_error_messages = {"invalid_uuid": "Not a valid UUID."}
def _validated(self, value) -> typing.Optional[uuid.UUID]:
"""Format the value or raise a :exc:`ValidationError` if an error occurs."""
if value is None:
return None
if isinstance(value, uuid.UUID):
return value
try:
if isinstance(value, bytes) and len(value) == 16:
return uuid.UUID(bytes=value)
else:
return uuid.UUID(value)
except (ValueError, AttributeError, TypeError) as error:
raise self.make_error("invalid_uuid") from error
def _deserialize(self, value, attr, data, **kwargs) -> typing.Optional[uuid.UUID]:
return self._validated(value)
class Number(Field):
"""Base class for number fields.
:param bool as_string: If `True`, format the serialized value as a string.
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
num_type = float # type: typing.Type
#: Default error messages.
default_error_messages = {
"invalid": "Not a valid number.",
"too_large": "Number too large.",
}
def __init__(self, *, as_string: bool = False, **kwargs):
self.as_string = as_string
super().__init__(**kwargs)
def _format_num(self, value) -> typing.Any:
"""Return the number value for value, given this field's `num_type`."""
return self.num_type(value)
def _validated(self, value) -> typing.Optional[_T]:
"""Format the value or raise a :exc:`ValidationError` if an error occurs."""
if value is None:
return None
# (value is True or value is False) is ~5x faster than isinstance(value, bool)
if value is True or value is False:
raise self.make_error("invalid", input=value)
try:
return self._format_num(value)
except (TypeError, ValueError) as error:
raise self.make_error("invalid", input=value) from error
except OverflowError as error:
raise self.make_error("too_large", input=value) from error
def _to_string(self, value) -> str:
return str(value)
def _serialize(
self, value, attr, obj, **kwargs
) -> typing.Optional[typing.Union[str, _T]]:
"""Return a string if `self.as_string=True`, otherwise return this field's `num_type`."""
if value is None:
return None
ret = self._format_num(value) # type: _T
return self._to_string(ret) if self.as_string else ret
def _deserialize(self, value, attr, data, **kwargs) -> typing.Optional[_T]:
return self._validated(value)
class Integer(Number):
"""An integer field.
:param strict: If `True`, only integer types are valid.
Otherwise, any value castable to `int` is valid.
:param kwargs: The same keyword arguments that :class:`Number` receives.
"""
num_type = int
#: Default error messages.
default_error_messages = {"invalid": "Not a valid integer."}
def __init__(self, *, strict: bool = False, **kwargs):
self.strict = strict
super().__init__(**kwargs)
# override Number
def _validated(self, value):
if self.strict:
if isinstance(value, numbers.Number) and isinstance(
value, numbers.Integral
):
return super()._validated(value)
raise self.make_error("invalid", input=value)
return super()._validated(value)
class Float(Number):
"""A double as an IEEE-754 double precision string.
:param bool allow_nan: If `True`, `NaN`, `Infinity` and `-Infinity` are allowed,
even though they are illegal according to the JSON specification.
:param bool as_string: If `True`, format the value as a string.
:param kwargs: The same keyword arguments that :class:`Number` receives.
"""
num_type = float
#: Default error messages.
default_error_messages = {
"special": "Special numeric values (nan or infinity) are not permitted."
}
def __init__(self, *, allow_nan: bool = False, as_string: bool = False, **kwargs):
self.allow_nan = allow_nan
super().__init__(as_string=as_string, **kwargs)
def _validated(self, value):
num = super()._validated(value)
if self.allow_nan is False:
if math.isnan(num) or num == float("inf") or num == float("-inf"):
raise self.make_error("special")
return num
class Decimal(Number):
"""A field that (de)serializes to the Python ``decimal.Decimal`` type.
It's safe to use when dealing with money values, percentages, ratios
or other numbers where precision is critical.
.. warning::
This field serializes to a `decimal.Decimal` object by default. If you need
to render your data as JSON, keep in mind that the `json` module from the
standard library does not encode `decimal.Decimal`. Therefore, you must use
a JSON library that can handle decimals, such as `simplejson`, or serialize
to a string by passing ``as_string=True``.
.. warning::
If a JSON `float` value is passed to this field for deserialization it will
first be cast to its corresponding `string` value before being deserialized
to a `decimal.Decimal` object. The default `__str__` implementation of the
built-in Python `float` type may apply a destructive transformation upon
its input data and therefore cannot be relied upon to preserve precision.
To avoid this, you can instead pass a JSON `string` to be deserialized
directly.
:param places: How many decimal places to quantize the value. If `None`, does
not quantize the value.
:param rounding: How to round the value during quantize, for example
`decimal.ROUND_UP`. If `None`, uses the rounding value from
the current thread's context.
:param allow_nan: If `True`, `NaN`, `Infinity` and `-Infinity` are allowed,
even though they are illegal according to the JSON specification.
:param as_string: If `True`, serialize to a string instead of a Python
`decimal.Decimal` type.
:param kwargs: The same keyword arguments that :class:`Number` receives.
.. versionadded:: 1.2.0
"""
num_type = decimal.Decimal
#: Default error messages.
default_error_messages = {
"special": "Special numeric values (nan or infinity) are not permitted."
}
def __init__(
self,
places: typing.Optional[int] = None,
rounding: typing.Optional[str] = None,
*,
allow_nan: bool = False,
as_string: bool = False,
**kwargs
):
self.places = (
decimal.Decimal((0, (1,), -places)) if places is not None else None
)
self.rounding = rounding
self.allow_nan = allow_nan
super().__init__(as_string=as_string, **kwargs)
# override Number
def _format_num(self, value):
num = decimal.Decimal(str(value))
if self.allow_nan:
if num.is_nan():
return decimal.Decimal("NaN") # avoid sNaN, -sNaN and -NaN
if self.places is not None and num.is_finite():
num = num.quantize(self.places, rounding=self.rounding)
return num
# override Number
def _validated(self, value):
try:
num = super()._validated(value)
except decimal.InvalidOperation as error:
raise self.make_error("invalid") from error
if not self.allow_nan and (num.is_nan() or num.is_infinite()):
raise self.make_error("special")
return num
# override Number
def _to_string(self, value):
return format(value, "f")
class Boolean(Field):
"""A boolean field.
:param truthy: Values that will (de)serialize to `True`. If an empty
set, any non-falsy value will deserialize to `True`. If `None`,
`marshmallow.fields.Boolean.truthy` will be used.
:param falsy: Values that will (de)serialize to `False`. If `None`,
`marshmallow.fields.Boolean.falsy` will be used.
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
#: Default truthy values.
truthy = {
"t",
"T",
"true",
"True",
"TRUE",
"on",
"On",
"ON",
"y",
"Y",
"yes",
"Yes",
"YES",
"1",
1,
True,
}
#: Default falsy values.
falsy = {
"f",
"F",
"false",
"False",
"FALSE",
"off",
"Off",
"OFF",
"n",
"N",
"no",
"No",
"NO",
"0",
0,
0.0,
False,
}
#: Default error messages.
default_error_messages = {"invalid": "Not a valid boolean."}
def __init__(
self,
*,
truthy: typing.Optional[typing.Set] = None,
falsy: typing.Optional[typing.Set] = None,
**kwargs
):
super().__init__(**kwargs)
if truthy is not None:
self.truthy = set(truthy)
if falsy is not None:
self.falsy = set(falsy)
def _serialize(self, value, attr, obj, **kwargs):
if value is None:
return None
try:
if value in self.truthy:
return True
elif value in self.falsy:
return False
except TypeError:
pass
return bool(value)
def _deserialize(self, value, attr, data, **kwargs):
if not self.truthy:
return bool(value)
else:
try:
if value in self.truthy:
return True
elif value in self.falsy:
return False
except TypeError as error:
raise self.make_error("invalid", input=value) from error
raise self.make_error("invalid", input=value)
class DateTime(Field):
"""A formatted datetime string.
Example: ``'2014-12-22T03:12:58.019077+00:00'``
:param format: Either ``"rfc"`` (for RFC822), ``"iso"`` (for ISO8601),
or a date format string. If `None`, defaults to "iso".
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionchanged:: 3.0.0rc9
Does not modify timezone information on (de)serialization.
"""
SERIALIZATION_FUNCS = {
"iso": utils.isoformat,
"iso8601": utils.isoformat,
"rfc": utils.rfcformat,
"rfc822": utils.rfcformat,
} # type: typing.Dict[str, typing.Callable[[typing.Any], str]]
DESERIALIZATION_FUNCS = {
"iso": utils.from_iso_datetime,
"iso8601": utils.from_iso_datetime,
"rfc": utils.from_rfc,
"rfc822": utils.from_rfc,
} # type: typing.Dict[str, typing.Callable[[str], typing.Any]]
DEFAULT_FORMAT = "iso"
OBJ_TYPE = "datetime"
SCHEMA_OPTS_VAR_NAME = "datetimeformat"
#: Default error messages.
default_error_messages = {
"invalid": "Not a valid {obj_type}.",
"invalid_awareness": "Not a valid {awareness} {obj_type}.",
"format": '"{input}" cannot be formatted as a {obj_type}.',
}
def __init__(self, format: typing.Optional[str] = None, **kwargs):
super().__init__(**kwargs)
# Allow this to be None. It may be set later in the ``_serialize``
# or ``_deserialize`` methods. This allows a Schema to dynamically set the
# format, e.g. from a Meta option
self.format = format
def _bind_to_schema(self, field_name, schema):
super()._bind_to_schema(field_name, schema)
self.format = (
self.format
or getattr(self.root.opts, self.SCHEMA_OPTS_VAR_NAME)
or self.DEFAULT_FORMAT
)
def _serialize(self, value, attr, obj, **kwargs):
if value is None:
return None
data_format = self.format or self.DEFAULT_FORMAT
format_func = self.SERIALIZATION_FUNCS.get(data_format)
if format_func:
return format_func(value)
else:
return value.strftime(data_format)
def _deserialize(self, value, attr, data, **kwargs):
if not value: # Falsy values, e.g. '', None, [] are not valid
raise self.make_error("invalid", input=value, obj_type=self.OBJ_TYPE)
data_format = self.format or self.DEFAULT_FORMAT
func = self.DESERIALIZATION_FUNCS.get(data_format)
if func:
try:
return func(value)
except (TypeError, AttributeError, ValueError) as error:
raise self.make_error(
"invalid", input=value, obj_type=self.OBJ_TYPE
) from error
else:
try:
return self._make_object_from_format(value, data_format)
except (TypeError, AttributeError, ValueError) as error:
raise self.make_error(
"invalid", input=value, obj_type=self.OBJ_TYPE
) from error
@staticmethod
def _make_object_from_format(value, data_format):
return dt.datetime.strptime(value, data_format)
class NaiveDateTime(DateTime):
"""A formatted naive datetime string.
:param format: See :class:`DateTime`.
:param timezone: Used on deserialization. If `None`,
aware datetimes are rejected. If not `None`, aware datetimes are
converted to this timezone before their timezone information is
removed.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionadded:: 3.0.0rc9
"""
AWARENESS = "naive"
def __init__(
self,
format: typing.Optional[str] = None,
*,
timezone: typing.Optional[dt.timezone] = None,
**kwargs
):
super().__init__(format=format, **kwargs)
self.timezone = timezone
def _deserialize(self, value, attr, data, **kwargs):
ret = super()._deserialize(value, attr, data, **kwargs)
if is_aware(ret):
if self.timezone is None:
raise self.make_error(
"invalid_awareness",
awareness=self.AWARENESS,
obj_type=self.OBJ_TYPE,
)
ret = ret.astimezone(self.timezone).replace(tzinfo=None)
return ret
class AwareDateTime(DateTime):
"""A formatted aware datetime string.
:param format: See :class:`DateTime`.
:param default_timezone: Used on deserialization. If `None`, naive
datetimes are rejected. If not `None`, naive datetimes are set this
timezone.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionadded:: 3.0.0rc9
"""
AWARENESS = "aware"
def __init__(
self,
format: typing.Optional[str] = None,
*,
default_timezone: typing.Optional[dt.tzinfo] = None,
**kwargs
):
super().__init__(format=format, **kwargs)
self.default_timezone = default_timezone
def _deserialize(self, value, attr, data, **kwargs):
ret = super()._deserialize(value, attr, data, **kwargs)
if not is_aware(ret):
if self.default_timezone is None:
raise self.make_error(
"invalid_awareness",
awareness=self.AWARENESS,
obj_type=self.OBJ_TYPE,
)
ret = ret.replace(tzinfo=self.default_timezone)
return ret
class Time(DateTime):
"""A formatted time string.
Example: ``'03:12:58.019077'``
:param format: Either ``"iso"`` (for ISO8601) or a date format string.
If `None`, defaults to "iso".
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
SERIALIZATION_FUNCS = {"iso": utils.to_iso_time, "iso8601": utils.to_iso_time}
DESERIALIZATION_FUNCS = {"iso": utils.from_iso_time, "iso8601": utils.from_iso_time}
DEFAULT_FORMAT = "iso"
OBJ_TYPE = "time"
SCHEMA_OPTS_VAR_NAME = "timeformat"
@staticmethod
def _make_object_from_format(value, data_format):
return dt.datetime.strptime(value, data_format).time()
class Date(DateTime):
"""ISO8601-formatted date string.
:param format: Either ``"iso"`` (for ISO8601) or a date format string.
If `None`, defaults to "iso".
:param kwargs: The same keyword arguments that :class:`Field` receives.
"""
#: Default error messages.
default_error_messages = {
"invalid": "Not a valid date.",
"format": '"{input}" cannot be formatted as a date.',
}
SERIALIZATION_FUNCS = {"iso": utils.to_iso_date, "iso8601": utils.to_iso_date}
DESERIALIZATION_FUNCS = {"iso": utils.from_iso_date, "iso8601": utils.from_iso_date}
DEFAULT_FORMAT = "iso"
OBJ_TYPE = "date"
SCHEMA_OPTS_VAR_NAME = "dateformat"
@staticmethod
def _make_object_from_format(value, data_format):
return dt.datetime.strptime(value, data_format).date()
class TimeDelta(Field):
"""A field that (de)serializes a :class:`datetime.timedelta` object to an
integer and vice versa. The integer can represent the number of days,
seconds or microseconds.
:param precision: Influences how the integer is interpreted during
(de)serialization. Must be 'days', 'seconds', 'microseconds',
'milliseconds', 'minutes', 'hours' or 'weeks'.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. versionchanged:: 2.0.0
Always serializes to an integer value to avoid rounding errors.
Add `precision` parameter.
"""
DAYS = "days"
SECONDS = "seconds"
MICROSECONDS = "microseconds"
MILLISECONDS = "milliseconds"
MINUTES = "minutes"
HOURS = "hours"
WEEKS = "weeks"
#: Default error messages.
default_error_messages = {
"invalid": "Not a valid period of time.",
"format": "{input!r} cannot be formatted as a timedelta.",
}
def __init__(self, precision: str = SECONDS, **kwargs):
precision = precision.lower()
units = (
self.DAYS,
self.SECONDS,
self.MICROSECONDS,
self.MILLISECONDS,
self.MINUTES,
self.HOURS,
self.WEEKS,
)
if precision not in units:
msg = 'The precision must be {} or "{}".'.format(
", ".join(['"{}"'.format(each) for each in units[:-1]]), units[-1]
)
raise ValueError(msg)
self.precision = precision
super().__init__(**kwargs)
def _serialize(self, value, attr, obj, **kwargs):
if value is None:
return None
base_unit = dt.timedelta(**{self.precision: 1})
return int(value.total_seconds() / base_unit.total_seconds())
def _deserialize(self, value, attr, data, **kwargs):
try:
value = int(value)
except (TypeError, ValueError) as error:
raise self.make_error("invalid") from error
kwargs = {self.precision: value}
try:
return dt.timedelta(**kwargs)
except OverflowError as error:
raise self.make_error("invalid") from error
class Mapping(Field):
"""An abstract class for objects with key-value pairs.
:param keys: A field class or instance for dict keys.
:param values: A field class or instance for dict values.
:param kwargs: The same keyword arguments that :class:`Field` receives.
.. note::
When the structure of nested data is not known, you may omit the
`keys` and `values` arguments to prevent content validation.
.. versionadded:: 3.0.0rc4
"""
mapping_type = dict
#: Default error messages.
default_error_messages = {"invalid": "Not a valid mapping type."}
def __init__(
self,
keys: typing.Optional[typing.Union[Field, type]] = None,
values: typing.Optional[typing.Union[Field, type]] = None,
**kwargs
):
super().__init__(**kwargs)
if keys is None:
self.key_field = None
else:
try:
self.key_field = resolve_field_instance(keys)
except FieldInstanceResolutionError as error:
raise ValueError(
'"keys" must be a subclass or instance of '
"marshmallow.base.FieldABC."
) from error
if values is None:
self.value_field = None
else:
try:
self.value_field = resolve_field_instance(values)
except FieldInstanceResolutionError as error:
raise ValueError(
'"values" must be a subclass or instance of '
"marshmallow.base.FieldABC."
) from error
if isinstance(self.value_field, Nested):
self.only = self.value_field.only
self.exclude = self.value_field.exclude
def _bind_to_schema(self, field_name, schema):
super()._bind_to_schema(field_name, schema)
if self.value_field:
self.value_field = copy.deepcopy(self.value_field)
self.value_field._bind_to_schema(field_name, self)
if isinstance(self.value_field, Nested):
self.value_field.only = self.only
self.value_field.exclude = self.exclude
if self.key_field:
self.key_field = copy.deepcopy(self.key_field)
self.key_field._bind_to_schema(field_name, self)
def _serialize(self, value, attr, obj, **kwargs):
if value is None:
return None
if not self.value_field and not self.key_field:
return self.mapping_type(value)
# Serialize keys
if self.key_field is None:
keys = {k: k for k in value.keys()}
else:
keys = {
k: self.key_field._serialize(k, None, None, **kwargs)
for k in value.keys()
}
# Serialize values
result = self.mapping_type()
if self.value_field is None:
for k, v in value.items():
if k in keys:
result[keys[k]] = v
else:
for k, v in value.items():
result[keys[k]] = self.value_field._serialize(v, None, None, **kwargs)
return result
def _deserialize(self, value, attr, data, **kwargs):
if not isinstance(value, _Mapping):
raise self.make_error("invalid")
if not self.value_field and not self.key_field:
return self.mapping_type(value)
errors = collections.defaultdict(dict)
# Deserialize keys
if self.key_field is None:
keys = {k: k for k in value.keys()}
else:
keys = {}
for key in value.keys():
try:
keys[key] = self.key_field.deserialize(key, **kwargs)
except ValidationError as error:
errors[key]["key"] = error.messages
# Deserialize values
result = self.mapping_type()
if self.value_field is None:
for k, v in value.items():
if k in keys:
result[keys[k]] = v
else:
for key, val in value.items():
try:
deser_val = self.value_field.deserialize(val, **kwargs)
except ValidationError as error:
errors[key]["value"] = error.messages
if error.valid_data is not None and key in keys:
result[keys[key]] = error.valid_data
else:
if key in keys:
result[keys[key]] = deser_val
if errors:
raise ValidationError(errors, valid_data=result)
return result
class Dict(Mapping):
"""A dict field. Supports dicts and dict-like objects. Extends
Mapping with dict as the mapping_type.
Example: ::
numbers = fields.Dict(keys=fields.Str(), values=fields.Float())
:param kwargs: The same keyword arguments that :class:`Mapping` receives.
.. versionadded:: 2.1.0
"""
mapping_type = dict
class Url(String):
"""An URL field.
:param default: Default value for the field if the attribute is not set.
:param relative: Whether to allow relative URLs.
:param require_tld: Whether to reject non-FQDN hostnames.
:param schemes: Valid schemes. By default, ``http``, ``https``,
``ftp``, and ``ftps`` are allowed.
:param kwargs: The same keyword arguments that :class:`String` receives.
"""
#: Default error messages.
default_error_messages = {"invalid": "Not a valid URL."}
def __init__(
self,
*,
relative: bool = False,
schemes: typing.Optional[types.StrSequenceOrSet] = None,
require_tld: bool = True,
**kwargs
):
super().__init__(**kwargs)
self.relative = relative
self.require_tld = require_tld
# Insert validation into self.validators so that multiple errors can be stored.
validator = validate.URL(
relative=self.relative,
schemes=schemes,
require_tld=self.require_tld,
error=self.error_messages["invalid"],
)
self.validators.insert(0, validator)
class Email(String):
"""An email field.
:param args: The same positional arguments that :class:`String` receives.
:param kwargs: The same keyword arguments that :class:`String` receives.
"""
#: Default error messages.
default_error_messages = {"invalid": "Not a valid email address."}
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
# Insert validation into self.validators so that multiple errors can be stored.
validator = validate.Email(error=self.error_messages["invalid"])
self.validators.insert(0, validator)
class IP(Field):
"""A IP address field.
:param bool exploded: If `True`, serialize ipv6 address in long form, ie. with groups
consisting entirely of zeros included.
.. versionadded:: 3.8.0
"""
default_error_messages = {"invalid_ip": "Not a valid IP address."}
DESERIALIZATION_CLASS = None # type: typing.Optional[typing.Type]
def __init__(self, *args, exploded=False, **kwargs):
super().__init__(*args, **kwargs)
self.exploded = exploded
def _serialize(self, value, attr, obj, **kwargs) -> typing.Optional[str]:
if value is None:
return None
if self.exploded:
return value.exploded
return value.compressed
def _deserialize(
self, value, attr, data, **kwargs
) -> typing.Optional[typing.Union[ipaddress.IPv4Address, ipaddress.IPv6Address]]:
if value is None:
return None
try:
return (self.DESERIALIZATION_CLASS or ipaddress.ip_address)(
utils.ensure_text_type(value)
)
except (ValueError, TypeError) as error:
raise self.make_error("invalid_ip") from error
class IPv4(IP):
"""A IPv4 address field.
.. versionadded:: 3.8.0
"""
default_error_messages = {"invalid_ip": "Not a valid IPv4 address."}
DESERIALIZATION_CLASS = ipaddress.IPv4Address
class IPv6(IP):
"""A IPv6 address field.
.. versionadded:: 3.8.0
"""
default_error_messages = {"invalid_ip": "Not a valid IPv6 address."}
DESERIALIZATION_CLASS = ipaddress.IPv6Address
class IPInterface(Field):
"""A IPInterface field.
IP interface is the non-stict form of the IPNetwork type where arbitrary host
addresses are always accepted.
IPAddress and mask e.g. '192.168.0.2/24' or '192.168.0.2/255.255.255.0'
see https://python.readthedocs.io/en/latest/library/ipaddress.html#interface-objects
:parm bool exploded: If `True`, serialize ipv6 interface in long form, ie. with groups
consisting entirely of zeros included.
"""
default_error_messages = {"invalid_ip_interface": "Not a valid IP interface."}
DESERIALIZATION_CLASS = None # type: typing.Optional[typing.Type]
def __init__(self, *args, exploded=False, **kwargs):
super().__init__(*args, **kwargs)
self.exploded = exploded
def _serialize(self, value, attr, obj, **kwargs) -> typing.Optional[str]:
if value is None:
return None
if self.exploded:
return value.exploded
return value.compressed
def _deserialize(
self, value, attr, data, **kwargs
) -> typing.Optional[
typing.Union[ipaddress.IPv4Interface, ipaddress.IPv6Interface]
]:
if value is None:
return None
try:
return (self.DESERIALIZATION_CLASS or ipaddress.ip_interface)(
utils.ensure_text_type(value)
)
except (ValueError, TypeError) as error:
raise self.make_error("invalid_ip_interface") from error
class IPv4Interface(IPInterface):
"""A IPv4 Network Interface field."""
default_error_messages = {"invalid_ip_interface": "Not a valid IPv4 interface."}
DESERIALIZATION_CLASS = ipaddress.IPv4Interface
class IPv6Interface(IPInterface):
"""A IPv6 Network Interface field."""
default_error_messages = {"invalid_ip_interface": "Not a valid IPv6 interface."}
DESERIALIZATION_CLASS = ipaddress.IPv6Interface
class Method(Field):
"""A field that takes the value returned by a `Schema` method.
:param str serialize: The name of the Schema method from which
to retrieve the value. The method must take an argument ``obj``
(in addition to self) that is the object to be serialized.
:param str deserialize: Optional name of the Schema method for deserializing
a value The method must take a single argument ``value``, which is the
value to deserialize.
.. versionchanged:: 2.0.0
Removed optional ``context`` parameter on methods. Use ``self.context`` instead.
.. versionchanged:: 2.3.0
Deprecated ``method_name`` parameter in favor of ``serialize`` and allow
``serialize`` to not be passed at all.
.. versionchanged:: 3.0.0
Removed ``method_name`` parameter.
"""
_CHECK_ATTRIBUTE = False
def __init__(
self,
serialize: typing.Optional[str] = None,
deserialize: typing.Optional[str] = None,
**kwargs
):
# Set dump_only and load_only based on arguments
kwargs["dump_only"] = bool(serialize) and not bool(deserialize)
kwargs["load_only"] = bool(deserialize) and not bool(serialize)
super().__init__(**kwargs)
self.serialize_method_name = serialize
self.deserialize_method_name = deserialize
self._serialize_method = None
self._deserialize_method = None
def _bind_to_schema(self, field_name, schema):
if self.serialize_method_name:
self._serialize_method = utils.callable_or_raise(
getattr(schema, self.serialize_method_name)
)
if self.deserialize_method_name:
self._deserialize_method = utils.callable_or_raise(
getattr(schema, self.deserialize_method_name)
)
super()._bind_to_schema(field_name, schema)
def _serialize(self, value, attr, obj, **kwargs):
if self._serialize_method is not None:
return self._serialize_method(obj)
return missing_
def _deserialize(self, value, attr, data, **kwargs):
if self._deserialize_method is not None:
return self._deserialize_method(value)
return value
class Function(Field):
"""A field that takes the value returned by a function.
:param serialize: A callable from which to retrieve the value.
The function must take a single argument ``obj`` which is the object
to be serialized. It can also optionally take a ``context`` argument,
which is a dictionary of context variables passed to the serializer.
If no callable is provided then the ```load_only``` flag will be set
to True.
:param deserialize: A callable from which to retrieve the value.
The function must take a single argument ``value`` which is the value
to be deserialized. It can also optionally take a ``context`` argument,
which is a dictionary of context variables passed to the deserializer.
If no callable is provided then ```value``` will be passed through
unchanged.
.. versionchanged:: 2.3.0
Deprecated ``func`` parameter in favor of ``serialize``.
.. versionchanged:: 3.0.0a1
Removed ``func`` parameter.
"""
_CHECK_ATTRIBUTE = False
def __init__(
self,
serialize: typing.Optional[
typing.Union[
typing.Callable[[typing.Any], typing.Any],
typing.Callable[[typing.Any, typing.Dict], typing.Any],
]
] = None,
deserialize: typing.Optional[
typing.Union[
typing.Callable[[typing.Any], typing.Any],
typing.Callable[[typing.Any, typing.Dict], typing.Any],
]
] = None,
**kwargs
):
# Set dump_only and load_only based on arguments
kwargs["dump_only"] = bool(serialize) and not bool(deserialize)
kwargs["load_only"] = bool(deserialize) and not bool(serialize)
super().__init__(**kwargs)
self.serialize_func = serialize and utils.callable_or_raise(serialize)
self.deserialize_func = deserialize and utils.callable_or_raise(deserialize)
def _serialize(self, value, attr, obj, **kwargs):
return self._call_or_raise(self.serialize_func, obj, attr)
def _deserialize(self, value, attr, data, **kwargs):
if self.deserialize_func:
return self._call_or_raise(self.deserialize_func, value, attr)
return value
def _call_or_raise(self, func, value, attr):
if len(utils.get_func_args(func)) > 1:
if self.parent.context is None:
msg = "No context available for Function field {!r}".format(attr)
raise ValidationError(msg)
return func(value, self.parent.context)
else:
return func(value)
class Constant(Field):
"""A field that (de)serializes to a preset constant. If you only want the
constant added for serialization or deserialization, you should use
``dump_only=True`` or ``load_only=True`` respectively.
:param constant: The constant to return for the field attribute.
.. versionadded:: 2.0.0
"""
_CHECK_ATTRIBUTE = False
def __init__(self, constant: typing.Any, **kwargs):
super().__init__(**kwargs)
self.constant = constant
self.missing = constant
self.default = constant
def _serialize(self, value, *args, **kwargs):
return self.constant
def _deserialize(self, value, *args, **kwargs):
return self.constant
class Inferred(Field):
"""A field that infers how to serialize, based on the value type.
.. warning::
This class is treated as private API.
Users should not need to use this class directly.
"""
def __init__(self):
super().__init__()
# We memoize the fields to avoid creating and binding new fields
# every time on serialization.
self._field_cache = {}
def _serialize(self, value, attr, obj, **kwargs):
field_cls = self.root.TYPE_MAPPING.get(type(value))
if field_cls is None:
field = super()
else:
field = self._field_cache.get(field_cls)
if field is None:
field = field_cls()
field._bind_to_schema(self.name, self.parent)
self._field_cache[field_cls] = field
return field._serialize(value, attr, obj, **kwargs)
# Aliases
URL = Url
Str = String
Bool = Boolean
Int = Integer