# -*- coding: utf-8 -*-
from __future__ import unicode_literals
from calendar import timegm
from datetime import date, datetime
from decimal import Decimal, ROUND_HALF_EVEN
from email.utils import formatdate
from six import iteritems, itervalues, text_type
from flask import url_for, request
from flask.ext.restful import fields as base_fields
from werkzeug import cached_property
from ._compat import urlparse, urlunparse
from .marshalling import marshal
from .utils import camel_to_dash, not_none
__all__ = ('Raw', 'String', 'FormattedString', 'Url', 'DateTime',
'Boolean', 'Integer', 'Float', 'Arbitrary', 'Fixed',
'Nested', 'List', 'ClassName', 'Polymorph',
'StringMixin', 'MinMaxMixin', 'NumberMixin', 'MarshallingException')
[docs]class MarshallingException(Exception):
'''
This is an encapsulating Exception in case of marshalling error.
'''
def __init__(self, underlying_exception):
# just put the contextual representation of the error to hint on what
# went wrong without exposing internals
super(MarshallingException, self).__init__(text_type(underlying_exception))
def is_indexable_but_not_string(obj):
return not hasattr(obj, "strip") and hasattr(obj, "__iter__")
def get_value(key, obj, default=None):
'''Helper for pulling a keyed value off various types of objects'''
if isinstance(key, int):
return _get_value_for_key(key, obj, default)
elif callable(key):
return key(obj)
else:
return _get_value_for_keys(key.split('.'), obj, default)
def _get_value_for_keys(keys, obj, default):
if len(keys) == 1:
return _get_value_for_key(keys[0], obj, default)
else:
return _get_value_for_keys(
keys[1:], _get_value_for_key(keys[0], obj, default), default)
def _get_value_for_key(key, obj, default):
if is_indexable_but_not_string(obj):
try:
return obj[key]
except (IndexError, TypeError, KeyError):
pass
return getattr(obj, key, default)
def to_marshallable_type(obj):
'''
Helper for converting an object to a dictionary only if it is not
dictionary already or an indexable object nor a simple type
'''
if obj is None:
return None # make it idempotent for None
if hasattr(obj, '__marshallable__'):
return obj.__marshallable__()
if hasattr(obj, '__getitem__'):
return obj # it is indexable it is ok
return dict(obj.__dict__)
[docs]class Raw(object):
'''
Raw provides a base field class from which others 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. Fields should
throw a :class:`MarshallingException` in case of parsing problem.
:param default: The default value for the field, if no value is
specified.
:param attribute: If the public facing value differs from the internal
value, use this to retrieve a different attribute from the response
than the publicly named value.
:param title: The field title (for documentation purpose)
:type title: str
:param description: The field description (for documentation purpose)
:type description: str
:param required: Is the field required ?
:type required: bool
:param readonly: Is the field read only ? (for documentation purpose)
:type readonly: bool
:param example: An optionnal data example (for documentation purpose)
:param mask: An optionnal mask function to be applied to output
:type mask: callable
'''
#: The JSON/Swagger schema type
__schema_type__ = 'object'
#: The JSON/Swagger schema format
__schema_format__ = None
#: An optionnal JSON/Swagger schema example
__schema_example__ = None
def __init__(self, default=None, attribute=None, title=None, description=None,
required=None, readonly=None, example=None, mask=None):
self.attribute = attribute
self.default = default
self.title = title
self.description = description
self.required = required
self.readonly = readonly
self.example = example or self.__schema_example__
self.mask = mask
[docs] def output(self, key, obj):
'''
Pulls the value for the given key from the object, applies the
field's formatting and returns the result. If the key is not found
in the object, returns the default value. Field classes that create
values which do not require the existence of the key in the object
should override this and return the desired value.
:raises MarshallingException: In case of formatting problem
'''
value = get_value(key if self.attribute is None else self.attribute, obj)
if value is None:
return self.default
data = self.format(value)
return self.mask(data) if self.mask else data
@cached_property
def __schema__(self):
return not_none(self.schema())
def schema(self):
return {
'type': self.__schema_type__,
'format': self.__schema_format__,
'title': self.title,
'description': self.description,
'readOnly': self.readonly,
'default': self.default,
'example': self.example,
}
[docs]class Nested(Raw):
'''
Allows you to nest one set of fields inside another.
See :ref:`nested-field` for more information
:param dict model: The model dictionary to nest
:param bool allow_null: Whether to return None instead of a dictionary
with null keys, if a nested dictionary has all-null keys
:param kwargs: If ``default`` keyword argument is present, a nested
dictionary will be marshaled as its value if nested dictionary is
all-null keys (e.g. lets you return an empty JSON object instead of
null)
'''
__schema_type__ = None
def __init__(self, model, allow_null=False, as_list=False, **kwargs):
self.model = model
self.as_list = as_list
self.allow_null = allow_null
super(Nested, self).__init__(**kwargs)
@property
def nested(self):
return getattr(self.model, 'resolved', self.model)
def output(self, key, obj):
value = get_value(key if self.attribute is None else self.attribute, obj)
if value is None:
if self.allow_null:
return None
elif self.default is not None:
return self.default
return marshal(value, self.nested)
def schema(self):
schema = super(Nested, self).schema()
ref = '#/definitions/{0}'.format(self.nested.name)
if self.as_list:
schema['type'] = 'array'
schema['items'] = {'$ref': ref}
else:
schema['$ref'] = ref
# if not self.allow_null and not self.readonly:
# schema['required'] = True
return schema
def clone(self):
kwargs = self.__dict__.copy()
return Nested(kwargs.pop('model').copy(), **kwargs)
[docs]class List(Raw):
'''
Field for marshalling lists of other fields.
See :ref:`list-field` for more information.
:param cls_or_instance: The field type the list will contain.
'''
def __init__(self, cls_or_instance, **kwargs):
self.min_items = kwargs.pop('min_items', None)
self.max_items = kwargs.pop('max_items', None)
self.unique = kwargs.pop('unique', None)
super(List, self).__init__(**kwargs)
error_msg = 'The type of the list elements must be a subclass of fields.Raw'
if isinstance(cls_or_instance, type):
if not issubclass(cls_or_instance, Raw):
raise MarshallingException(error_msg)
self.container = cls_or_instance()
else:
if not isinstance(cls_or_instance, Raw):
raise MarshallingException(error_msg)
self.container = cls_or_instance
def format(self, value):
# Convert all instances in typed list to container type
if isinstance(value, set):
value = list(value)
is_nested = isinstance(self.container, Nested) or type(self.container) is Raw
def is_attr(val):
return self.container.attribute and hasattr(val, self.container.attribute)
return [
self.container.output(idx,
val if (isinstance(val, dict) or is_attr(val)) and not is_nested else value)
for idx, val in enumerate(value)
]
def output(self, key, data):
value = get_value(key if self.attribute is None else self.attribute, data)
# we cannot really test for external dict behavior
if is_indexable_but_not_string(value) and not isinstance(value, dict):
return self.format(value)
if value is None:
return self.default
return [marshal(value, self.container.nested)]
def schema(self):
schema = super(List, self).schema()
schema.update(minItems=self.min_items, maxItems=self.max_items, uniqueItems=self.unique)
schema['type'] = 'array'
schema['items'] = self.container.__schema__
return schema
def clone(self):
kwargs = self.__dict__.copy()
cls = kwargs.pop('container')
return List(cls, **kwargs)
class StringMixin(object):
__schema_type__ = 'string'
def __init__(self, *args, **kwargs):
self.min_length = kwargs.pop('min_length', None)
self.max_length = kwargs.pop('max_length', None)
self.pattern = kwargs.pop('pattern', None)
super(StringMixin, self).__init__(*args, **kwargs)
def schema(self):
schema = super(StringMixin, self).schema()
schema.update(minLength=self.min_length, maxLength=self.max_length, pattern=self.pattern)
return schema
class MinMaxMixin(object):
def __init__(self, *args, **kwargs):
self.minimum = kwargs.pop('min', None)
self.excluisveMinimum = kwargs.pop('exclusiveMin', None)
self.maximum = kwargs.pop('max', None)
self.exclusiveMaximum = kwargs.pop('exclusiveMax', None)
super(MinMaxMixin, self).__init__(*args, **kwargs)
def schema(self):
schema = super(MinMaxMixin, self).schema()
schema.update(minimum=self.minimum, exclusiveMinimum=self.excluisveMinimum,
maximum=self.maximum, exclusiveMaximum=self.exclusiveMaximum)
return schema
class NumberMixin(MinMaxMixin):
__schema_type__ = 'number'
def __init__(self, *args, **kwargs):
self.multiple = kwargs.pop('multiple', None)
super(NumberMixin, self).__init__(*args, **kwargs)
def schema(self):
schema = super(NumberMixin, self).schema()
schema.update(multipleOf=self.multiple)
return schema
[docs]class String(StringMixin, Raw):
'''
Marshal a value as a string. Uses ``six.text_type`` so values will
be converted to :class:`unicode` in python2 and :class:`str` in
python3.
'''
def __init__(self, *args, **kwargs):
self.enum = kwargs.pop('enum', None)
self.discriminator = kwargs.pop('discriminator', None)
super(String, self).__init__(*args, **kwargs)
self.required = self.discriminator or self.required
def format(self, value):
try:
return text_type(value)
except ValueError as ve:
raise MarshallingException(ve)
def schema(self):
enum = self.enum() if callable(self.enum) else self.enum
schema = super(String, self).schema()
schema.update(enum=enum)
if enum and schema['example'] is None:
schema['example'] = enum[0]
return schema
[docs]class Integer(NumberMixin, Raw):
'''
Field for outputting an integer value.
:param default: The default value for the field, if no value is specified.
:type default: int
'''
__schema_type__ = 'integer'
def format(self, value):
try:
if value is None:
return self.default
return int(value)
except ValueError as ve:
raise MarshallingException(ve)
[docs]class Float(NumberMixin, Raw):
'''
A double as IEEE-754 double precision.
ex : 3.141592653589793 3.1415926535897933e-06 3.141592653589793e+24 nan inf -inf
'''
def format(self, value):
try:
return float(value)
except ValueError as ve:
raise MarshallingException(ve)
[docs]class Arbitrary(NumberMixin, Raw):
'''
A floating point number with an arbitrary precision.
ex: 634271127864378216478362784632784678324.23432
'''
def format(self, value):
return text_type(Decimal(value))
ZERO = Decimal()
[docs]class Fixed(NumberMixin, Raw):
'''
A decimal number with a fixed precision.
'''
def __init__(self, decimals=5, **kwargs):
super(Fixed, self).__init__(**kwargs)
self.precision = Decimal('0.' + '0' * (decimals - 1) + '1')
def format(self, value):
dvalue = Decimal(value)
if not dvalue.is_normal() and dvalue != ZERO:
raise MarshallingException('Invalid Fixed precision number.')
return text_type(dvalue.quantize(self.precision, rounding=ROUND_HALF_EVEN))
[docs]class Boolean(Raw):
'''
Field for outputting a boolean value.
Empty collections such as ``""``, ``{}``, ``[]``, etc. will be converted to ``False``.
'''
__schema_type__ = 'boolean'
def format(self, value):
return bool(value)
[docs]class DateTime(MinMaxMixin, Raw):
'''
Return a formatted datetime string in UTC. Supported formats are RFC 822 and ISO 8601.
See :func:`email.utils.formatdate` for more info on the RFC 822 format.
See :meth:`datetime.datetime.isoformat` for more info on the ISO 8601 format.
:param str dt_format: ``rfc822`` or ``iso8601``
'''
__schema_type__ = 'string'
__schema_format__ = 'date-time'
def __init__(self, dt_format='rfc822', **kwargs):
super(DateTime, self).__init__(**kwargs)
self.dt_format = dt_format
if self.minimum and isinstance(self.minimum, (date, datetime)):
self.minimum = self.minimum.isoformat()
if self.maximum and isinstance(self.maximum, (date, datetime)):
self.maximum = self.maximum.isoformat()
def format(self, value):
try:
if self.dt_format == 'rfc822':
return self.format_rfc822(value)
elif self.dt_format == 'iso8601':
return self.format_iso8601(value)
else:
raise MarshallingException(
'Unsupported date format %s' % self.dt_format
)
except AttributeError as ae:
raise MarshallingException(ae)
[docs]class Url(StringMixin, Raw):
'''
A string representation of a Url
:param endpoint: Endpoint name. If endpoint is ``None``, ``request.endpoint`` is used instead
:type endpoint: str
:param absolute: If ``True``, ensures that the generated urls will have the hostname included
:type absolute: bool
:param scheme: URL scheme specifier (e.g. ``http``, ``https``)
:type scheme: str
'''
def __init__(self, endpoint=None, absolute=False, scheme=None, **kwargs):
super(Url, self).__init__(**kwargs)
self.endpoint = endpoint
self.absolute = absolute
self.scheme = scheme
def output(self, key, obj):
try:
data = to_marshallable_type(obj)
endpoint = self.endpoint if self.endpoint is not None else request.endpoint
o = urlparse(url_for(endpoint, _external=self.absolute, **data))
if self.absolute:
scheme = self.scheme if self.scheme is not None else o.scheme
return urlunparse((scheme, o.netloc, o.path, "", "", ""))
return urlunparse(("", "", o.path, "", "", ""))
except TypeError as te:
raise MarshallingException(te)
[docs]class ClassName(String):
'''
Return the serialized object class name as string.
:param bool dash: If `True`, transform CamelCase to kebab_case.
'''
def __init__(self, dash=False, **kwargs):
super(ClassName, self).__init__(**kwargs)
self.dash = dash
def output(self, key, obj):
classname = obj.__class__.__name__
return camel_to_dash(classname) if self.dash else classname
[docs]class Polymorph(Nested):
'''
A Nested field handling inheritance.
Allows you to specify a mapping between Python classes and fields specifications.
.. code-block:: python
mapping = {
Child1: child1_fields,
Child2: child2_fields,
}
fields = api.model('Thing', {
owner: fields.Polymorph(mapping)
})
:param dict mapping: Maps classes to their model/fields representation
'''
def __init__(self, mapping, required=False, **kwargs):
self.mapping = mapping
parent = self.resolve_ancestor(list(itervalues(mapping)))
super(Polymorph, self).__init__(parent, allow_null=not required, **kwargs)
def output(self, key, obj):
# Copied from upstream NestedField
value = base_fields.get_value(key if self.attribute is None else self.attribute, obj)
if value is None:
if self.allow_null:
return None
elif self.default is not None:
return self.default
# Handle mappings
if not hasattr(value, '__class__'):
raise ValueError('Polymorph field only accept class instances')
candidates = [fields for cls, fields in iteritems(self.mapping) if isinstance(value, cls)]
if len(candidates) <= 0:
raise ValueError('Unknown class: ' + value.__class__.__name__)
elif len(candidates) > 1:
raise ValueError('Unable to determine a candidate for: ' + value.__class__.__name__)
else:
return base_fields.marshal(value, candidates[0].resolved)
[docs] def resolve_ancestor(self, fields):
'''
Resolve the common ancestor for all fields.
Assume there is only one common ancestor.
'''
trees = [set(f.tree) for f in fields]
candidates = set.intersection(*trees)
if len(candidates) != 1:
field_names = [f.name for f in fields]
raise ValueError('Unable to determine the common ancestor for: ' + ', '.join(field_names))
parent_name = candidates.pop()
return fields[0].get_parent(parent_name)