deb-python-wsme/wsme/rest/json.py

"""
REST+Json protocol implementation.
"""
from __future__ import absolute_import
import datetime
import decimal

import six

from simplegeneric import generic

from wsme.types import Unset
import wsme.types
from wsme.exc import UnknownArgument

try:
    import simplejson as json
except ImportError:
    import json  # noqa


content_type = 'application/json'
accept_content_types = [
    content_type,
    'text/javascript',
    'application/javascript'
]


@generic
def tojson(datatype, value):
    """
    A generic converter from python to jsonify-able datatypes.

    If a non-complex user specific type is to be used in the api,
    a specific tojson should be added::

        from wsme.protocol.restjson import tojson

        myspecialtype = object()

        @tojson.when_object(myspecialtype)
        def myspecialtype_tojson(datatype, value):
            return str(value)
    """
    if wsme.types.iscomplex(datatype):
        d = dict()
        for attr in wsme.types.list_attributes(datatype):
            attr_value = getattr(value, attr.key)
            if attr_value is not Unset:
                d[attr.name] = tojson(attr.datatype, attr_value)
        return d
    elif wsme.types.isusertype(datatype):
        return tojson(datatype.basetype, datatype.tobasetype(value))
    return value


@tojson.when_object(wsme.types.bytes)
def bytes_tojson(datatype, value):
    if value is None:
        return None
    return value.decode('ascii')


@tojson.when_type(wsme.types.ArrayType)
def array_tojson(datatype, value):
    if value is None:
        return None
    return [tojson(datatype.item_type, item) for item in value]


@tojson.when_type(wsme.types.DictType)
def dict_tojson(datatype, value):
    if value is None:
        return None
    return dict((
        (tojson(datatype.key_type, item[0]),
            tojson(datatype.value_type, item[1]))
        for item in value.items()
    ))


@tojson.when_object(decimal.Decimal)
def decimal_tojson(datatype, value):
    if value is None:
        return None
    return str(value)


@tojson.when_object(datetime.date)
def date_tojson(datatype, value):
    if value is None:
        return None
    return value.isoformat()


@tojson.when_object(datetime.time)
def time_tojson(datatype, value):
    if value is None:
        return None
    return value.isoformat()


@tojson.when_object(datetime.datetime)
def datetime_tojson(datatype, value):
    if value is None:
        return None
    return value.isoformat()


@generic
def fromjson(datatype, value):
    """
    A generic converter from json base types to python datatype.

    If a non-complex user specific type is to be used in the api,
    a specific fromjson should be added::

        from wsme.protocol.restjson import fromjson

        class MySpecialType(object):
            pass

        @fromjson.when_object(MySpecialType)
        def myspecialtype_fromjson(datatype, value):
            return MySpecialType(value)
    """
    if value is None:
        return None
    if wsme.types.iscomplex(datatype):
        obj = datatype()
        for attrdef in wsme.types.list_attributes(datatype):
            if attrdef.name in value:
                setattr(obj, attrdef.key,
                        fromjson(attrdef.datatype, value[attrdef.name]))
        return obj
    elif wsme.types.isusertype(datatype):
        value = datatype.frombasetype(
            fromjson(datatype.basetype, value))
    return value


@fromjson.when_type(wsme.types.ArrayType)
def array_fromjson(datatype, value):
    if value is None:
        return None
    return [fromjson(datatype.item_type, item) for item in value]


@fromjson.when_type(wsme.types.DictType)
def dict_fromjson(datatype, value):
    if value is None:
        return None
    return dict((
        (fromjson(datatype.key_type, item[0]),
            fromjson(datatype.value_type, item[1]))
        for item in value.items()))


@fromjson.when_object(six.binary_type)
def str_fromjson(datatype, value):
    if value is None:
        return None
    return value.encode('utf8')


@fromjson.when_object(wsme.types.text)
def text_fromjson(datatype, value):
    if value is not None and isinstance(value, wsme.types.bytes):
        return wsme.types.text(value)
    return value


@fromjson.when_object(decimal.Decimal)
def decimal_fromjson(datatype, value):
    if value is None:
        return None
    return decimal.Decimal(value)


@fromjson.when_object(datetime.date)
def date_fromjson(datatype, value):
    if value is None:
        return None
    return datetime.datetime.strptime(value, '%Y-%m-%d').date()


@fromjson.when_object(datetime.time)
def time_fromjson(datatype, value):
    if value is None:
        return None
    return datetime.datetime.strptime(value, '%H:%M:%S').time()


@fromjson.when_object(datetime.datetime)
def datetime_fromjson(datatype, value):
    if value is None:
        return None
    return datetime.datetime.strptime(value, '%Y-%m-%dT%H:%M:%S')


def parse(s, datatypes, bodyarg, encoding='utf8'):
    if hasattr(s, 'read'):
        jdata = json.load(s)
    else:
        if six.PY3 and isinstance(s, six.binary_type):
            s = s.decode(encoding)
        jdata = json.loads(s)
    if bodyarg:
        argname = list(datatypes.keys())[0]
        kw = {argname: fromjson(datatypes[argname], jdata)}
    else:
        kw = {}
        extra_args = []
        for key in jdata:
            if key not in datatypes:
                extra_args.append(key)
            else:
                kw[key] = fromjson(datatypes[key], jdata[key])
        if extra_args:
            raise UnknownArgument(', '.join(extra_args))
    return kw


def encode_result(value, datatype, **options):
    jsondata = tojson(datatype, value)
    if options.get('nest_result', False):
        jsondata = {options.get('nested_result_attrname', 'result'): jsondata}
    return json.dumps(jsondata)


def encode_error(context, errordetail):
    return json.dumps(errordetail)


def encode_sample_value(datatype, value, format=False):
    r = tojson(datatype, value)
    content = json.dumps(r, ensure_ascii=False,
        indent=4 if format else 0,
        sort_keys=format)
    return ('javascript', content)


def encode_sample_params(params, format=False):
    kw = {}
    for name, datatype, value in params:
        kw[name] = tojson(datatype, value)
    content = json.dumps(kw, ensure_ascii=False,
        indent=4 if format else 0,
        sort_keys=format)
    return ('javascript', content)


def encode_sample_result(datatype, value, format=False):
    r = tojson(datatype, value)
    #if self.nest_result:
        #r = {'result': r}
    content = json.dumps(r, ensure_ascii=False,
        indent=4 if format else 0,
        sort_keys=format)
    return ('javascript', content)