所以我发现自己需要在Python字典中添加前缀。
基本上我想要的是这个字典的用户能够在字典的实例化中添加前缀,在这种情况下字典保存前缀,并且每次添加新密钥时,它都会预先添加前缀。但是如果由于某种原因没有提供或更改前缀,我也想要改变字典,这意味着旧的字典键需要在保留各自值的同时为它们添加前缀。
用例:
基本上我正在完成MWS API的最后一次api。 我建立了api围绕着每个调用需要采取特定参数的想法, 喜欢:
def get_report(self, marketplaceids):
# Here I process marketplaceids which is a python list
# and send the following to Amazon:
MarketplaceIdList.Id.1: 123,
MarketplaceIdList.Id.2: 345,
MarketplaceIdList.Id.3: 4343
# By doing this I eliminate the complexity of the arguments Amazon expects
不幸的是,最后两个api更难以这种方式实现,因为它们使用了亚马逊引入的名为Datatypes
的新“功能”。
这些“Datatypes
”是嵌套结构。
例如:
我想调用CreateInboundShipment
,
InboundShipmentAPI
操作
该操作采用以下参数:
ShipmentId - String
InboundShipmentHeader - InboundShipmentHeader datatype
InboundShipmentItems - A list of InboundShipmentItem datatypes
问题发生的原因是InboundShipmentHeader是一种数据类型,它将另一种数据类型作为参数。 亚马逊最终期望以下内容:
ShipmentId=102038383
InboundShipmentHeader.ShipmentName': 'somevalue',
InboundShipmentHeader.ShipFromAddress.Name': 'somevalue',
InboundShipmentHeader.ShipFromAddress.AddressLine1': 'somevalue',
InboundShipmentHeader.ShipFromAddress.City': 'somevalue',
InboundShipmentHeader.ShipFromAddress.StateOrProvinceCode': 'somevalue',
InboundShipmentHeader.ShipFromAddress.PostalCode': 'somevalue',
InboundShipmentHeader.ShipFromAddress.CountryCode': 'somevalue',
InboundShipmentHeader.DestinationFulfillmentCenterId': 'somevalue',
InboundShipmentHeader.ShipmentStatus': 'somevalue',
InboundShipmentHeader.LabelPrepPreference': 'somevalue',
InboundShipmentItems.member.1.QuantityShipped': 'somevalue',
InboundShipmentItems.member.2.QuantityShipped': 'somevalue',
InboundShipmentItems.member.1.SellerSKU': 'somevalue',
InboundShipmentItems.member.2.SellerSKU': 'somevalue',
InboundShipmentHeader.ShipFromAddress.AddressLine2': 'somevalue',
InboundShipmentHeader.ShipFromAddress.DistrictOrCounty': 'somevalue',
所以我想简单地让某人做这个电话而不必担心每个参数的名字。 我的解决方案是创建一个基本数据类型类,然后创建单独的数据类型 作为课程。
这是我到目前为止所做的:
class AmazonDataType(dict):
"""
Base for all Amazon datatypes.
"""
def __init__(self, *args, **kwargs):
self._prefix = kwargs.pop('prefix', '')
self.update(*args, **kwargs)
@property
def prefix(self):
return self._prefix
@prefix.setter
def prefix(self, value):
self._prefix = value
newdict = {'%s.%s' % (value, key): dictvalue for key, dictvalue in self.iteritems()}
self.clear()
dict.update(self, newdict)
def __setitem__(self, key, value):
try:
original_key = self.fields[key]
except KeyError, e:
raise e
if isinstance(value, AmazonDataType):
value.prefix = original_key
dict.update(self, value)
else:
newkey = self.prefix + original_key if self.prefix else original_key
dict.__setitem__(self, newkey, value)
def update(self, *args, **kwargs):
"""
Props to Matt Anderson (http://stackoverflow.com/a/2390997/389453)
"""
for k, v in dict(*args, **kwargs).iteritems():
self[k] = v
class InboundShipmentHeader(AmazonDataType):
fields = {
'name': 'ShipmentName',
'address': 'ShipFromAddress',
'fulfillment_center_id': 'DestinationFulfillmentCenterId',
'label_preference': 'LabelPrepPreference',
'cases_required': 'AreCasesRequired',
'shipment_status': 'ShipmentStatus',
}
然后而不是做
somedict = {
'InboundShipmentHeader.ShipmentName': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.Name': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.AddressLine1': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.City': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.StateOrProvinceCode': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.PostalCode': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.CountryCode': 'somevalue',
'InboundShipmentHeader.DestinationFulfillmentCenterId': 'somevalue',
'InboundShipmentHeader.ShipmentStatus': 'somevalue',
'InboundShipmentHeader.LabelPrepPreference': 'somevalue',
}
call_amazon(somedict)
我想传递类似
的内容ShipmentHeader = InboundShipmentHeader()
ShipmentHeader['name'] = 'somevalue'
ShipmentHeader['address'] = address_datatype_instance
ShipmentHeader['fulfillment_center_id'] = 'somevalue'
ShipmentHeader['label_preference'] = 'somevalue'
ShipmentHeader['cases_required'] = 'somevalue'
ShipmentHeader['shipment_status'] = 'somevalue'
call_amazon(ShipmentHeader, otherparams)
在后台,call_amazon
方法执行:
ShipmentHeader.prefix = InboundShipmentHeader
答案 0 :(得分:4)
你可以继承dict
并添加一个方法(我不知道该怎么称呼它,所以让我们说dict
):
class AmazonDataType(dict):
"""
Base for all Amazon datatypes.
"""
def __init__(self, *args, **kwargs):
self._prefix = kwargs.pop('prefix', self.__class__.__name__)
super(AmazonDataType, self).__init__(*args, **kwargs)
def __getattr__(self, key):
return self.__getitem__(key)
def __setattr__(self, key, value):
return self.__setitem__(key, value)
def dict(self):
result = {}
for key, value in self.items():
if key.startswith('_'):
continue
key = self.fields.get(key, key)
if isinstance(value, AmazonDataType):
for skey, svalue in value.dict().items():
result['%s.%s' % (self._prefix, skey)] = svalue
else:
result['%s.%s' % (self._prefix, key)] = value
return result
现在,界面更像Pythonic:
class InboundShipmentHeader(AmazonDataType):
fields = {
'name': 'ShipmentName',
'address': 'ShipFromAddress',
'fulfillment_center_id': 'DestinationFulfillmentCenterId',
'label_preference': 'LabelPrepPreference',
'cases_required': 'AreCasesRequired',
'shipment_status': 'ShipmentStatus',
}
class Address(AmazonDataType):
fields = {
'name': 'Name',
'address': 'AddressLine1',
'city': 'City'
}
address = Address(prefix='ShipFromAddress')
address.name = 'Foo'
header = InboundShipmentHeader()
header.name = 'somevalue'
header.address = address
header.fulfillment_center_id = 'somevalue'
header.label_preference = 'somevalue'
header.cases_required = 'somevalue'
header.shipment_status = 'somevalue'
header.dict()
的输出是:
{'InboundShipmentHeader.AreCasesRequired': 'somevalue',
'InboundShipmentHeader.DestinationFulfillmentCenterId': 'somevalue',
'InboundShipmentHeader.LabelPrepPreference': 'somevalue',
'InboundShipmentHeader.ShipFromAddress.Name': 'Foo',
'InboundShipmentHeader.ShipmentName': 'somevalue',
'InboundShipmentHeader.ShipmentStatus': 'somevalue'}
答案 1 :(得分:2)
从它的外观来看,你在抽象类中需要的翻译有点复杂,只是在字典键前面加上。
我可能会将翻译逻辑封装在基类中,并为每种类型创建子类,使用类似的东西......
class AmazonDict(dict):
translation_dict = {}
def __init__(self, prefix):
self.prefix = prefix
def translate(self):
result = {}
for k, v in self.iteritems():
if k not in self.translation_dict:
continue
if isinstance(v, AmazonDict):
for sk, sv in v.translate().iteritems():
sk = '%s.%s' % (self.prefix, sk)
result[sk] = sv
else:
k = '%s.%s' % (self.prefix, self.translation_dict[k])
result[k] = v
return result
class ShipmentAddress(AmazonDict):
translation_dict = {'name': 'Name',
'line1': 'AddressLine1'}
class ShipmentHeader(AmazonDict):
translation_dict = {'name': 'ShipmentName',
'address': 'ShipFromAddress'}
address = ShipmentAddress('ShipFromAddress')
address['name'] = 'Fred Bloggs'
address['line1'] = '123 High Street'
header = ShipmentHeader('InboundShipmentHeader')
header['name'] = 'Something'
header['address'] = address
pprint.pprint(header.translate())
...它还处理子'对象'的递归,并输出......
{'InboundShipmentHeader.ShipFromAddress.AddressLine1': '123 High Street',
'InboundShipmentHeader.ShipFromAddress.Name': 'Fred Bloggs',
'InboundShipmentHeader.ShipmentName': 'Something'}
...假设这是亚马逊期待的格式。