Fields<a class="headerlink" href="#module-marshmallow.fields" title="Permalink to this headline">¶

Default error messages.

default_error_messages = {'format': '"{input}" cannot be formatted as a date.', 'invalid': 'Not a valid date.'}¶: Default error messages.

class marshmallow.fields.DateTime(format: str | None = None, **kwargs)[source]¶

A formatted datetime string.

Example: '2014-12-22T03:12:58.019077+00:00'

Parameters

format – Either "rfc" (for RFC822), "iso" (for ISO8601), or a date format string. If None, defaults to “iso”.
kwargs – The same keyword arguments that Field receives.

Changed in version 3.0.0rc9: Does not modify timezone information on (de)serialization.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'format': '"{input}" cannot be formatted as a {obj_type}.', 'invalid': 'Not a valid {obj_type}.', 'invalid_awareness': 'Not a valid {awareness} {obj_type}.'}¶: Default error messages.

class marshmallow.fields.Decimal(places: int | None = None, rounding: str | None = None, *, allow_nan: bool = False, as_string: bool = False, **kwargs)[source]¶

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.

Parameters

places – How many decimal places to quantize the value. If None, does not quantize the value.
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.
allow_nan – If True, NaN, Infinity and -Infinity are allowed, even though they are illegal according to the JSON specification.
as_string – If True, serialize to a string instead of a Python decimal.Decimal type.
kwargs – The same keyword arguments that Number receives.

New in version 1.2.0.

Methods:

`_format_num`(value)	Return the number value for value, given this field's `num_type`.
`_validated`(value)	Format the value or raise a `ValidationError` if an error occurs.

Attributes:

Default error messages.

Classes:

alias of decimal.Decimal

_format_num(value)[source]¶: Return the number value for value, given this field’s num_type.

_validated(value)[source]¶: Format the value or raise a ValidationError if an error occurs.

default_error_messages = {'special': 'Special numeric values (nan or infinity) are not permitted.'}¶: Default error messages.

num_type¶

alias of decimal.Decimal Methods:

`adjusted`()	Return the adjusted exponent of the number.
`as_integer_ratio`()	Return a pair of integers, whose ratio is exactly equal to the original Decimal and with a positive denominator.
`as_tuple`()	Return a tuple representation of the number.
`canonical`()	Return the canonical encoding of the argument.
`compare`(other[, context])	Compare self to other.
`compare_signal`(other[, context])	Identical to compare, except that all NaNs signal.
`compare_total`(other[, context])	Compare two operands using their abstract representation rather than their numerical value.
`compare_total_mag`(other[, context])	Compare two operands using their abstract representation rather than their value as in compare_total(), but ignoring the sign of each operand.
`conjugate`()	Return self.
`copy_abs`()	Return the absolute value of the argument.
`copy_negate`()	Return the negation of the argument.
`copy_sign`(other[, context])	Return a copy of the first operand with the sign set to be the same as the sign of the second operand.
`exp`([context])	Return the value of the (natural) exponential function e**x at the given number.
`fma`(other, third[, context])	Fused multiply-add.
`from_float`()	Class method that converts a float to a decimal number, exactly.
`is_canonical`()	Return True if the argument is canonical and False otherwise.
`is_finite`()	Return True if the argument is a finite number, and False if the argument is infinite or a NaN.
`is_infinite`()	Return True if the argument is either positive or negative infinity and False otherwise.
`is_nan`()	Return True if the argument is a (quiet or signaling) NaN and False otherwise.
`is_normal`([context])	Return True if the argument is a normal finite non-zero number with an adjusted exponent greater than or equal to Emin.
`is_qnan`()	Return True if the argument is a quiet NaN, and False otherwise.
`is_signed`()	Return True if the argument has a negative sign and False otherwise.
`is_snan`()	Return True if the argument is a signaling NaN and False otherwise.
`is_subnormal`([context])	Return True if the argument is subnormal, and False otherwise.
`is_zero`()	Return True if the argument is a (positive or negative) zero and False otherwise.
`ln`([context])	Return the natural (base e) logarithm of the operand.
`log10`([context])	Return the base ten logarithm of the operand.
`logb`([context])	For a non-zero number, return the adjusted exponent of the operand as a Decimal instance.
`logical_and`(other[, context])	Return the digit-wise 'and' of the two (logical) operands.
`logical_invert`([context])	Return the digit-wise inversion of the (logical) operand.
`logical_or`(other[, context])	Return the digit-wise 'or' of the two (logical) operands.
`logical_xor`(other[, context])	Return the digit-wise 'exclusive or' of the two (logical) operands.
`max`(other[, context])	Maximum of self and other.
`max_mag`(other[, context])	Similar to the max() method, but the comparison is done using the absolute values of the operands.
`min`(other[, context])	Minimum of self and other.
`min_mag`(other[, context])	Similar to the min() method, but the comparison is done using the absolute values of the operands.
`next_minus`([context])	Return the largest number representable in the given context (or in the current default context if no context is given) that is smaller than the given operand.
`next_plus`([context])	Return the smallest number representable in the given context (or in the current default context if no context is given) that is larger than the given operand.
`next_toward`(other[, context])	If the two operands are unequal, return the number closest to the first operand in the direction of the second operand.
`normalize`([context])	Normalize the number by stripping the rightmost trailing zeros and converting any result equal to Decimal('0') to Decimal('0e0').
`number_class`([context])	Return a string describing the class of the operand.
`quantize`(exp[, rounding, context])	Return a value equal to the first operand after rounding and having the exponent of the second operand.
`radix`()	Return Decimal(10), the radix (base) in which the Decimal class does all its arithmetic.
`remainder_near`(other[, context])	Return the remainder from dividing self by other.
`rotate`(other[, context])	Return the result of rotating the digits of the first operand by an amount specified by the second operand.
`same_quantum`(other[, context])	Test whether self and other have the same exponent or whether both are NaN.
`scaleb`(other[, context])	Return the first operand with the exponent adjusted the second.
`shift`(other[, context])	Return the result of shifting the digits of the first operand by an amount specified by the second operand.
`sqrt`([context])	Return the square root of the argument to full precision.
`to_eng_string`([context])	Convert to an engineering-type string.
`to_integral`([rounding, context])	Identical to the to_integral_value() method.
`to_integral_exact`([rounding, context])	Round to the nearest integer, signaling Inexact or Rounded as appropriate if rounding occurs.
`to_integral_value`([rounding, context])	Round to the nearest integer without signaling Inexact or Rounded.

class marshmallow.fields.Dict(keys: Field | type | None = None, values: Field | type | None = None, **kwargs)[source]¶

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())

Parameters: kwargs – The same keyword arguments that Mapping receives.

New in version 2.1.0.

Classes:

mapping_type

alias of dict

mapping_type¶

alias of dict Methods:

`clear`()
`copy`()
`fromkeys`([value])	Create a new dictionary with keys from iterable and values set to value.
`get`(key[, default])	Return the value for key if key is in the dictionary, else default.
`items`()
`keys`()
`pop`(k[,d])	If key is not found, d is returned if given, otherwise KeyError is raised
`popitem`()	Remove and return a (key, value) pair as a 2-tuple.
`setdefault`(key[, default])	Insert key with a value of default if key is not in the dictionary.
`update`([E, ]**F)	If E is present and has a .keys() method, then does: for k in E: D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]
`values`()

class marshmallow.fields.Email(*args, **kwargs)[source]¶

An email field.

Parameters

args – The same positional arguments that String receives.
kwargs – The same keyword arguments that String receives.

Attributes:

Default error messages.

default_error_messages = {'invalid': 'Not a valid email address.'}¶: Default error messages.

class marshmallow.fields.Field(*, load_default: typing.Any = <marshmallow.missing>, missing: typing.Any = <marshmallow.missing>, dump_default: typing.Any = <marshmallow.missing>, default: typing.Any = <marshmallow.missing>, data_key: str | None = None, attribute: str | None = None, validate: None | (typing.Callable[[typing.Any], typing.Any] | typing.Iterable[typing.Callable[[typing.Any], typing.Any]]) = None, required: bool = False, allow_none: bool | None = None, load_only: bool = False, dump_only: bool = False, error_messages: dict[str, str] | None = None, metadata: typing.Mapping[str, typing.Any] | None = None, **additional_metadata)[source]¶

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.

Parameters

dump_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.
load_default – Default deserialization value for the field if the field is not found in the input data. May be a value or a callable.
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.
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.
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 ValidationError is raised.
required – Raise a ValidationError if the field value is not supplied during deserialization.
allow_none – Set this to True if None should be considered a valid value during validation/deserialization. If load_default=None and allow_none is unset, will default to True. Otherwise, the default is False.
load_only – If True skip this field during serialization, otherwise its value will be present in the serialized data.
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”.
error_messages (dict) – Overrides for Field.default_error_messages.
metadata – Extra information to be stored as field metadata.

Changed in version 2.0.0: Removed error parameter. Use error_messages instead.

Changed in version 2.0.0: Added allow_none parameter, which makes validation/deserialization of None consistent across fields.

Changed in version 2.0.0: Added load_only and dump_only parameters, which allow field skipping during the (de)serialization process.

Changed in version 2.0.0: Added missing parameter, which indicates the value for a field if the field is not found during deserialization.

Changed in version 2.0.0: default value is only used if explicitly set. Otherwise, missing values inputs are excluded from serialized output.

Changed in version 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.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.
`_validate`(value)	Perform validation on `value`.
`_validate_missing`(value)	Validate missing values.
`deserialize`(value[, attr, data])	Deserialize `value`.
`fail`(key, **kwargs)	Helper method that raises a `ValidationError` with an error message from `self.error_messages`.
`get_value`(obj, attr[, accessor, default])	Return the value for a given key from an object.
`make_error`(key, **kwargs)	Helper method to make a `ValidationError` with an error message from `self.error_messages`.
`serialize`(attr, obj[, accessor])	Pulls the value for the given key from the object, applies the field's formatting and returns the result.

Attributes:

`context`	The context dictionary for the parent `Schema`.
`default_error_messages`	Default error messages for various kinds of errors.

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value: Any, attr: str | None, data: Mapping[str, Any] | None, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value: Any, attr: str, obj: Any, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

_validate(value)[source]¶: Perform validation on value. Raise a ValidationError if validation does not succeed.

_validate_missing(value)[source]¶: Validate missing values. Raise a ValidationError if value should be considered missing.

property context¶: The context dictionary for the parent Schema.

default_error_messages = {'null': 'Field may not be null.', 'required': 'Missing data for required field.', 'validator_failed': 'Invalid value.'}¶: 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 marshmallow.exceptions.ValidationError.

deserialize(value: Any, attr: str | None = None, data: Mapping[str, Any] | None = None, **kwargs)[source]¶

Deserialize value.

Parameters

value – The value to deserialize.
attr – The attribute/key in data to deserialize.
data – The raw input data passed to Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – If an invalid value is passed or if a required value is missing.

fail(key: str, **kwargs)[source]¶: Helper method that raises a ValidationError with an error message from self.error_messages.

Deprecated since version 3.0.0: Use make_error instead.

get_value(obj, attr, accessor=None, default=<marshmallow.missing>)[source]¶

Return the value for a given key from an object.

Parameters

obj (object) – The object to get the value from.
attr (str) – The attribute/key in obj to get the value from.
accessor (callable) – A callable used to retrieve the value of attr from the object obj. Defaults to marshmallow.utils.get_value.

make_error(key: str, **kwargs) → marshmallow.exceptions.ValidationError[source]¶: Helper method to make a ValidationError with an error message from self.error_messages.

serialize(attr: str, obj: Any, accessor: Callable[[Any, str, Any], Any] | None = None, **kwargs)[source]¶

Pulls the value for the given key from the object, applies the field’s formatting and returns the result.

Parameters

attr – The attribute/key to get from the object.
obj – The object to access the attribute/key from.
accessor – Function used to access values from obj.
kwargs – Field-specific keyword arguments.

class marshmallow.fields.Float(*, allow_nan: bool = False, as_string: bool = False, **kwargs)[source]¶

A double as an IEEE-754 double precision string.

Parameters

allow_nan (bool) – If True, NaN, Infinity and -Infinity are allowed, even though they are illegal according to the JSON specification.
as_string (bool) – If True, format the value as a string.
kwargs – The same keyword arguments that Number receives.

Methods:

_validated(value)

Format the value or raise a ValidationError if an error occurs.

Attributes:

Default error messages.

Classes:

see https://python.readthedocs.io/en/latest/library/ipaddress.html#interface-objects

alias of float

_validated(value)[source]¶: Format the value or raise a ValidationError if an error occurs.

default_error_messages = {'special': 'Special numeric values (nan or infinity) are not permitted.'}¶: Default error messages.

num_type¶

alias of float Methods:

`as_integer_ratio`()	Return integer ratio.
`conjugate`()	Return self, the complex conjugate of any float.
`fromhex`()	Create a floating-point number from a hexadecimal string.
`hex`()	Return a hexadecimal representation of a floating-point number.
`is_integer`()	Return True if the float is an integer.

Attributes:

`imag`	the imaginary part of a complex number
`real`	the real part of a complex number

class marshmallow.fields.Function(serialize: None | Callable[[Any], Any] | Callable[[Any, dict], Any] = None, deserialize: None | Callable[[Any], Any] | Callable[[Any, dict], Any] = None, **kwargs)[source]¶

A field that takes the value returned by a function.

Parameters

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.
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.

Changed in version 2.3.0: Deprecated func parameter in favor of serialize.

Changed in version 3.0.0a1: Removed func parameter.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

class marshmallow.fields.IP(*args, exploded=False, **kwargs)[source]¶

A IP address field.

Parameters: exploded (bool) – If True, serialize ipv6 address in long form, ie. with groups consisting entirely of zeros included.

New in version 3.8.0.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

_deserialize(value, attr, data, **kwargs) → ipaddress.IPv4Address | ipaddress.IPv6Address | None[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs) → str | None[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

class marshmallow.fields.IPInterface(*args, exploded=False, **kwargs)[source]¶

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’

Parameters: exploded (bool) – If True, serialize ipv6 interface in long form, ie. with groups consisting entirely of zeros included.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs) → str | None[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

class marshmallow.fields.IPv4(*args, exploded=False, **kwargs)[source]¶

A IPv4 address field.

New in version 3.8.0.

Classes:

alias of ipaddress.IPv4Address

DESERIALIZATION_CLASS¶

alias of ipaddress.IPv4Address Attributes:

`is_link_local`	Test if the address is reserved for link-local.
`is_loopback`	Test if the address is a loopback address.
`is_multicast`	Test if the address is reserved for multicast use.
`is_private`	Test if this address is allocated for private networks.
`is_reserved`	Test if the address is otherwise IETF reserved.
`is_unspecified`	Test if the address is unspecified.
`packed`	The binary representation of this address.

class marshmallow.fields.IPv4Interface(*args, exploded=False, **kwargs)[source]¶

A IPv4 Network Interface field.

Classes:

alias of ipaddress.IPv4Interface

DESERIALIZATION_CLASS¶: alias of ipaddress.IPv4Interface

class marshmallow.fields.IPv6(*args, exploded=False, **kwargs)[source]¶

A IPv6 address field.

New in version 3.8.0.

Classes:

alias of ipaddress.IPv6Address

DESERIALIZATION_CLASS¶

alias of ipaddress.IPv6Address Attributes:

`ipv4_mapped`	Return the IPv4 mapped address.
`is_global`	Test if this address is allocated for public networks.
`is_link_local`	Test if the address is reserved for link-local.
`is_loopback`	Test if the address is a loopback address.
`is_multicast`	Test if the address is reserved for multicast use.
`is_private`	Test if this address is allocated for private networks.
`is_reserved`	Test if the address is otherwise IETF reserved.
`is_site_local`	Test if the address is reserved for site-local.
`is_unspecified`	Test if the address is unspecified.
`packed`	The binary representation of this address.
`sixtofour`	Return the IPv4 6to4 embedded address.
`teredo`	Tuple of embedded teredo IPs.

class marshmallow.fields.IPv6Interface(*args, exploded=False, **kwargs)[source]¶

A IPv6 Network Interface field.

Classes:

alias of ipaddress.IPv6Interface

DESERIALIZATION_CLASS¶

alias of ipaddress.IPv6Interface Attributes:

`is_loopback`	Test if the address is a loopback address.
`is_unspecified`	Test if the address is unspecified.

marshmallow.fields.Int¶

alias of marshmallow.fields.Integer Methods:

_validated(value)

Format the value or raise a ValidationError if an error occurs.

Classes:

num_type

alias of int

class marshmallow.fields.Integer(*, strict: bool = False, **kwargs)[source]¶

An integer field.

Parameters

strict – If True, only integer types are valid. Otherwise, any value castable to int is valid.
kwargs – The same keyword arguments that Number receives.

Methods:

_validated(value)

Format the value or raise a ValidationError if an error occurs.

Attributes:

Default error messages.

Classes:

alias of int

_validated(value)[source]¶: Format the value or raise a ValidationError if an error occurs.

default_error_messages = {'invalid': 'Not a valid integer.'}¶: Default error messages.

num_type¶

alias of int Methods:

`as_integer_ratio`()	Return integer ratio.
`bit_length`()	Number of bits necessary to represent self in binary.
`conjugate`	Returns self, the complex conjugate of any int.
`from_bytes`(byteorder, *[, signed])	Return the integer represented by the given array of bytes.
`to_bytes`(length, byteorder, *[, signed])	Return an array of bytes representing an integer.

Attributes:

`denominator`	the denominator of a rational number in lowest terms
`imag`	the imaginary part of a complex number
`numerator`	the numerator of a rational number in lowest terms
`real`	the real part of a complex number

class marshmallow.fields.List(cls_or_instance: Field | type, **kwargs)[source]¶

A list field, composed with another Field class or instance.

Example:

numbers = fields.List(fields.Float())

Parameters

cls_or_instance – A field class or instance.
kwargs – The same keyword arguments that Field receives.

Changed in version 2.0.0: The allow_none parameter now applies to deserialization and has the same semantics as the other fields.

Changed in version 3.0.0rc9: Does not serialize scalar values to single-item lists.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value, attr, data, **kwargs) → list[Any][source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs) → list[Any] | None[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'invalid': 'Not a valid list.'}¶: Default error messages.

class marshmallow.fields.Mapping(keys: Field | type | None = None, values: Field | type | None = None, **kwargs)[source]¶

An abstract class for objects with key-value pairs.

Parameters

keys – A field class or instance for dict keys.
values – A field class or instance for dict values.
kwargs – The same keyword arguments that Field receives.

Note

When the structure of nested data is not known, you may omit the keys and values arguments to prevent content validation.

New in version 3.0.0rc4.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

Classes:

mapping_type

alias of dict

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'invalid': 'Not a valid mapping type.'}¶: Default error messages.

mapping_type¶

alias of dict Methods:

`clear`()
`copy`()
`fromkeys`([value])	Create a new dictionary with keys from iterable and values set to value.
`get`(key[, default])	Return the value for key if key is in the dictionary, else default.
`items`()
`keys`()
`pop`(k[,d])	If key is not found, d is returned if given, otherwise KeyError is raised
`popitem`()	Remove and return a (key, value) pair as a 2-tuple.
`setdefault`(key[, default])	Insert key with a value of default if key is not in the dictionary.
`update`([E, ]**F)	If E is present and has a .keys() method, then does: for k in E: D[k] = E[k] If E is present and lacks a .keys() method, then does: for k, v in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k]
`values`()

class marshmallow.fields.Method(serialize: str | None = None, deserialize: str | None = None, **kwargs)[source]¶

A field that takes the value returned by a Schema method.

Parameters

serialize (str) – 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.
deserialize (str) – Optional name of the Schema method for deserializing a value The method must take a single argument value, which is the value to deserialize.

Changed in version 2.0.0: Removed optional context parameter on methods. Use self.context instead.

Changed in version 2.3.0: Deprecated method_name parameter in favor of serialize and allow serialize to not be passed at all.

Changed in version 3.0.0: Removed method_name parameter.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

class marshmallow.fields.NaiveDateTime(format: str | None = None, *, timezone: dt.timezone | None = None, **kwargs)[source]¶

A formatted naive datetime string.

Parameters

format – See DateTime.
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.
kwargs – The same keyword arguments that Field receives.

New in version 3.0.0rc9.

Methods:

_deserialize(value, attr, data, **kwargs)

Deserialize value.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

Allows you to nest a 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 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 class (not an instance) as the first argument.

# Yes
author = fields.Nested(UserSchema, only=('id', 'name'))

# No
author = fields.Nested(UserSchema(), only=('id', 'name'))

Parameters

nested – Schema instance, class, class name (string), dictionary, or callable that returns a Schema or dictionary. Dictionaries are converted with Schema.from_dict.
exclude – A list or tuple of fields to exclude.
only – A list or tuple of fields to marshal. If None, all fields are marshalled. This parameter takes precedence over exclude.
many – Whether the field is a collection of objects.
unknown – Whether to exclude, include, or raise an error for unknown fields in the data. Use EXCLUDE, INCLUDE or RAISE.
kwargs – The same keyword arguments that Field receives.

Methods:

`_deserialize`(value, attr, data[, partial])	Same as `Field._deserialize()` with additional `partial` argument.
`_serialize`(nested_obj, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

`default_error_messages`	Default error messages.
`schema`	The nested Schema object.

_deserialize(value, attr, data, partial=None, **kwargs)[source]¶

Same as Field._deserialize() with additional partial argument.

Parameters: partial (bool|tuple) – For nested schemas, the partial parameter passed to Schema.load.

Changed in version 3.0.0: Add partial parameter.

_serialize(nested_obj, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'type': 'Invalid type.'}¶: Default error messages.

property schema¶: The nested Schema object.

Changed in version 1.0.0: Renamed from serializer to schema.

class marshmallow.fields.Number(*, as_string: bool = False, **kwargs)[source]¶

Base class for number fields.

Parameters

as_string (bool) – If True, format the serialized value as a string.
kwargs – The same keyword arguments that Field receives.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_format_num`(value)	Return the number value for value, given this field's `num_type`.
`_serialize`(value, attr, obj, **kwargs)	Return a string if `self.as_string=True`, otherwise return this field's `num_type`.
`_validated`(value)	Format the value or raise a `ValidationError` if an error occurs.

Attributes:

Default error messages.

Classes:

alias of float

_deserialize(value, attr, data, **kwargs) → _T | None[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_format_num(value) → Any[source]¶: Return the number value for value, given this field’s num_type.

_serialize(value, attr, obj, **kwargs) → str | _T | None[source]¶: Return a string if self.as_string=True, otherwise return this field’s num_type.

_validated(value) → _T | None[source]¶: Format the value or raise a ValidationError if an error occurs.

default_error_messages = {'invalid': 'Not a valid number.', 'too_large': 'Number too large.'}¶: Default error messages.

num_type¶

alias of float Methods:

`as_integer_ratio`()	Return integer ratio.
`conjugate`()	Return self, the complex conjugate of any float.
`fromhex`()	Create a floating-point number from a hexadecimal string.
`hex`()	Return a hexadecimal representation of a floating-point number.
`is_integer`()	Return True if the float is an integer.

Attributes:

`imag`	the imaginary part of a complex number
`real`	the real part of a complex number

class marshmallow.fields.Pluck(nested: SchemaABC | type | str | Callable[[], SchemaABC], field_name: str, **kwargs)[source]¶

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}

Parameters

nested (Schema) – The Schema class or class name (string) to nest, or "self" to nest the Schema within itself.
field_name (str) – The key to pluck a value from.
kwargs – The same keyword arguments that Nested receives.

Methods:

`_deserialize`(value, attr, data[, partial])	Same as `Field._deserialize()` with additional `partial` argument.
`_serialize`(nested_obj, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

_deserialize(value, attr, data, partial=None, **kwargs)[source]¶

Same as Field._deserialize() with additional partial argument.

Parameters: partial (bool|tuple) – For nested schemas, the partial parameter passed to Schema.load.

Changed in version 3.0.0: Add partial parameter.

_serialize(nested_obj, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

class marshmallow.fields.Raw(*, load_default: typing.Any = <marshmallow.missing>, missing: typing.Any = <marshmallow.missing>, dump_default: typing.Any = <marshmallow.missing>, default: typing.Any = <marshmallow.missing>, data_key: str | None = None, attribute: str | None = None, validate: None | (typing.Callable[[typing.Any], typing.Any] | typing.Iterable[typing.Callable[[typing.Any], typing.Any]]) = None, required: bool = False, allow_none: bool | None = None, load_only: bool = False, dump_only: bool = False, error_messages: dict[str, str] | None = None, metadata: typing.Mapping[str, typing.Any] | None = None, **additional_metadata)[source]¶: Field that applies no formatting.

marshmallow.fields.Str¶

alias of marshmallow.fields.String Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

class marshmallow.fields.String(*, load_default: typing.Any = <marshmallow.missing>, missing: typing.Any = <marshmallow.missing>, dump_default: typing.Any = <marshmallow.missing>, default: typing.Any = <marshmallow.missing>, data_key: str | None = None, attribute: str | None = None, validate: None | (typing.Callable[[typing.Any], typing.Any] | typing.Iterable[typing.Callable[[typing.Any], typing.Any]]) = None, required: bool = False, allow_none: bool | None = None, load_only: bool = False, dump_only: bool = False, error_messages: dict[str, str] | None = None, metadata: typing.Mapping[str, typing.Any] | None = None, **additional_metadata)[source]¶

A string field.

Parameters: kwargs – The same keyword arguments that Field receives.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

_deserialize(value, attr, data, **kwargs) → Any[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs) → str | None[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'invalid': 'Not a valid string.', 'invalid_utf8': 'Not a valid utf-8 string.'}¶: Default error messages.

class marshmallow.fields.Time(format: str | None = None, **kwargs)[source]¶

A formatted time string.

Example: '03:12:58.019077'

Parameters

format – Either "iso" (for ISO8601) or a date format string. If None, defaults to “iso”.
kwargs – The same keyword arguments that Field receives.

class marshmallow.fields.TimeDelta(precision: str = 'seconds', **kwargs)[source]¶

A field that (de)serializes a datetime.timedelta object to an integer and vice versa. The integer can represent the number of days, seconds or microseconds.

Parameters

precision – Influences how the integer is interpreted during (de)serialization. Must be ‘days’, ‘seconds’, ‘microseconds’, ‘milliseconds’, ‘minutes’, ‘hours’ or ‘weeks’.
kwargs – The same keyword arguments that Field receives.

Changed in version 2.0.0: Always serializes to an integer value to avoid rounding errors. Add precision parameter.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

_deserialize(value, attr, data, **kwargs)[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs)[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'format': '{input!r} cannot be formatted as a timedelta.', 'invalid': 'Not a valid period of time.'}¶: Default error messages.

class marshmallow.fields.Tuple(tuple_fields, *args, **kwargs)[source]¶

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.

Parameters

tuple_fields (Iterable[Field]) – An iterable of field classes or instances.
kwargs – The same keyword arguments that Field receives.

New in version 3.0.0rc4.

Methods:

`_bind_to_schema`(field_name, schema)	Update field with values from its parent schema.
`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_serialize`(value, attr, obj, **kwargs)	Serializes `value` to a basic Python datatype.

Attributes:

Default error messages.

_bind_to_schema(field_name, schema)[source]¶

Update field with values from its parent schema. Called by Schema._bind_field.

Parameters

field_name (str) – Field name set in schema.
schema (Schema|Field) – Parent object.

_deserialize(value, attr, data, **kwargs) → tuple[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_serialize(value, attr, obj, **kwargs) → tuple | None[source]¶

Serializes value to a basic Python datatype. Noop by default. Concrete 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()

Parameters

value – The value to be serialized.
attr (str) – The attribute or key on the object to be serialized.
obj (object) – The object the value was pulled from.
kwargs (dict) – Field-specific keyword arguments.

Returns

The serialized value

default_error_messages = {'invalid': 'Not a valid tuple.'}¶: Default error messages.

marshmallow.fields.URL¶: alias of marshmallow.fields.Url

class marshmallow.fields.UUID(*, load_default: typing.Any = <marshmallow.missing>, missing: typing.Any = <marshmallow.missing>, dump_default: typing.Any = <marshmallow.missing>, default: typing.Any = <marshmallow.missing>, data_key: str | None = None, attribute: str | None = None, validate: None | (typing.Callable[[typing.Any], typing.Any] | typing.Iterable[typing.Callable[[typing.Any], typing.Any]]) = None, required: bool = False, allow_none: bool | None = None, load_only: bool = False, dump_only: bool = False, error_messages: dict[str, str] | None = None, metadata: typing.Mapping[str, typing.Any] | None = None, **additional_metadata)[source]¶

A UUID field.

Methods:

`_deserialize`(value, attr, data, **kwargs)	Deserialize value.
`_validated`(value)	Format the value or raise a `ValidationError` if an error occurs.

Attributes:

Default error messages.

_deserialize(value, attr, data, **kwargs) → uuid.UUID | None[source]¶

Deserialize value. Concrete Field classes should implement this method.

Parameters

value – The value to be deserialized.
attr – The attribute/key in data to be deserialized.
data – The raw input data passed to the Schema.load.
kwargs – Field-specific keyword arguments.

Raises

ValidationError – In case of formatting or validation failure.

Returns

The deserialized value.

Changed in version 2.0.0: Added attr and data parameters.

Changed in version 3.0.0: Added **kwargs to signature.

_validated(value) → uuid.UUID | None[source]¶: Format the value or raise a ValidationError if an error occurs.

default_error_messages = {'invalid_uuid': 'Not a valid UUID.'}¶: Default error messages.

class marshmallow.fields.Url(*, relative: bool = False, schemes: types.StrSequenceOrSet | None = None, require_tld: bool = True, **kwargs)[source]¶

An URL field.

Parameters

default – Default value for the field if the attribute is not set.
relative – Whether to allow relative URLs.
require_tld – Whether to reject non-FQDN hostnames.
schemes – Valid schemes. By default, http, https, ftp, and ftps are allowed.
kwargs – The same keyword arguments that String receives.

Attributes: