Django实现支付宝付款和微信支付

支付宝支付和微信支付是当今互联网产品常用的功能，我使用Django Rest Framework实现了网页上支付宝支付和微信支付的一个通用服务，提供rpc接口给其他服务，包括获取支付宝支付页面url的rpc接口、支付宝支付成功异步回调http接口、获取微信支付二维码rpc接口、主动查询微信订单是否支付的rpc接口等。

支付宝网站支付需要蚂蚁金服开放平台账号，创建应用、配置秘钥等步骤请参考：蚂蚁金服支付宝电脑网站支付快速接入

微信网站支付需要到微信支付官网注册服务商账号，

目录结构如下：

1、models.py

from django.db import models
from django.contrib.postgres.fields import ArrayField


# Create your models here.


class BaseModel(models.Model):
    """
        基础模型
    """
    created_time = models.DateTimeField(auto_now_add=True, verbose_name="创建时间")
    updated_time = models.DateTimeField(auto_now=True, verbose_name="修改时间")
    created_by = models.IntegerField(verbose_name="创建人ID")
    updated_by = models.IntegerField(verbose_name="修改人ID")
    is_active = models.BooleanField(default=True, verbose_name='是否正常')

    class Meta:
        abstract = True


class Alipay(BaseModel):
    """
        支付
    """

    subject = models.CharField(max_length=256, verbose_name="订单标题")
    out_trade_no = models.CharField(max_length=64, unique=True, verbose_name="唯一订单号")
    trade_no = models.CharField(default="", max_length=64, verbose_name="支付宝系统中的交易流水号")
    total_amount = models.DecimalField(max_digits=11, decimal_places=2, verbose_name="订单的资金总额")
    return_url = models.CharField(max_length=500, verbose_name="支付完成同步跳转地址")
    notify_url = models.CharField(max_length=500, verbose_name="支付完成异步通知rpc地址")
    pay_time = models.DateTimeField(null=True, blank=True, verbose_name="支付时间")
    pay_nos = ArrayField(models.CharField(max_length=100), default=[], verbose_name='同一订单的支付ID数组')

    class Meta:
        verbose_name = "阿里支付"
        verbose_name_plural = verbose_name
        ordering = ('-created_time',)


class Wxorder(BaseModel):
    """
        订单
    """
    body = models.CharField(max_length=256, verbose_name="商品描述")
    out_trade_no = models.CharField(max_length=64, unique=True, verbose_name="订单号")
    transaction_id = models.CharField(default="", max_length=64, verbose_name="微信支付订单号")
    total_fee = models.BigIntegerField(verbose_name="订单的资金总额,单位为分")
    product_id = models.CharField(max_length=16, verbose_name="商品ID")
    notify_url = models.CharField(max_length=500, verbose_name="支付完成通知url")
    pay_time = models.DateTimeField(null=True, blank=True, verbose_name="支付时间")

    class Meta:
        verbose_name = "微信订单"
        verbose_name_plural = verbose_name
        ordering = ('-created_time',)


class Wxpay(BaseModel):
    """
        微信支付
    """
    out_trade_no = models.CharField(null=True, blank=True, max_length=64, verbose_name="订单号")
    pay_no = models.CharField(null=True, blank=True, max_length=64, unique=True, verbose_name="支付唯一订单号")
    code_url = models.CharField(null=True, blank=True, max_length=100, verbose_name="二维码地址")
    nonce_str = models.CharField(null=True, blank=True, max_length=32, verbose_name="随机字符串")

    class Meta:
        verbose_name = "微信支付"
        verbose_name_plural = verbose_name
        ordering = ('-created_time',)

2、serializers.py：

from django.conf import settings
from rest_framework import serializers

from pay.models import Alipay, Wxpay


class BaseSerializer(serializers.ModelSerializer):
    created_time = serializers.DateTimeField(format=settings.DATETIME_FORMAT, read_only=True)
    updated_time = serializers.DateTimeField(format=settings.DATETIME_FORMAT, read_only=True)
    is_active = serializers.BooleanField(read_only=True)

    class Meta:
        model = None


class AlipaySerializer(BaseSerializer):
    """
        阿里支付序列化类
    """

    class Meta:
        model = Alipay
        fields = "__all__"


class WxpaySerializer(BaseSerializer):
    """
        阿里支付序列化类
    """

    class Meta:
        model = Wxpay
        fields = "__all__"

3、views.py：

# -*- coding=utf-8 -*-
# Create your views here.
import time
import dicttoxml

from jsonrpc import jsonrpc_method
from rest_framework.decorators import list_route
from rest_framework.response import Response
from rest_framework.viewsets import ModelViewSet
from rest_framework.views import APIView
from rest_framework_xml.parsers import XMLParser
from rest_framework_xml.renderers import XMLRenderer
from tokenauth.decorators import is_login

from pay import utils
from pay.weixin_pay import WeiXinPay, UnifiedOrderPay, OrderQuery
from pay.UUIDTools import UUIDTools
from pay.models import Alipay, Wxpay, Wxorder
from pay.serializers import AlipaySerializer, WxpaySerializer
from pay.utils import UnActiveModelMixin
from pay.alipay import AliPay
from PAY_SERVICE.settings.base import APPID, PRIVATE_KEY_PATH, 
    ALI_PUB_KEY_PATH, ALIPAY_CALLBACK_URL, 
    WXAPPID, WX_PAY_KEY, WX_MCH_ID, WXPAY_CALLBACK_URL

NOTIFY_URL = ALIPAY_CALLBACK_URL + 'api/v1.0/pay/alipay/notify/'



class AlipayViewSet(ModelViewSet):
    queryset = Alipay.objects.filter(is_active=True)
    serializer_class = AlipaySerializer

    @list_route(methods=['post'])
    def notify(self, request):
        """ 
            处理支付宝的notify_url
        :param request:
        :return:
        """
        processed_dict = {}
        for k, v in request.data.items():
            processed_dict[k] = v
        app_id = processed_dict.get('app_id')
        pay_no = processed_dict.get('out_trade_no')
        trade_no = processed_dict.get('trade_no')
        total_amount = processed_dict.get('total_amount')
        pay_time = time.strftime('%Y-%m-%d %H:%M:%S',time.localtime())

        alipay = Alipay.objects.filter(pay_nos__contains=[pay_no]).values().first()
        if alipay is None:
            return Response("failed")
        if str(alipay.get('total_amount')) != str(total_amount):
            return Response("failed")
        if app_id != APPID:
            return Response("failed")
        if alipay.get('trade_no') != "":
            return Response("failed")

        sign = processed_dict.pop('sign', None)

        ali_pay = AliPay(
            appid=APPID,
            app_notify_url=NOTIFY_URL,
            app_private_key_path=PRIVATE_KEY_PATH,
            alipay_public_key_path=ALI_PUB_KEY_PATH,
            debug=True,  # 默认False,
            return_url=alipay.get('return_url')
        )

        is_verify = ali_pay.verify(processed_dict, sign)

        if is_verify is True:
            Alipay.objects.filter(pk=alipay.get('id')).update(pay_time=pay_time, trade_no=trade_no)
            ret = utils.request_thrift('TradingManager', 'notify',
                settings.TRADING_RPC_IP, int(settings.TRADING_RPC_PORT),
                alipay.get('out_trade_no'), str(pay_time))
            if ret == "success":
                return Response("success")


class WxpayViewSet(ModelViewSet):
    queryset = Wxpay.objects.filter(is_active=True)
    serializer_class = WxpaySerializer
    parser_classes = (XMLParser,)
    renderer_classes = (XMLRenderer,)


@jsonrpc_method('pay.get_alipay_url')
def get_alipay_url(request, subject, out_trade_no, total_amount, return_url, notify_url, user_id):
    recode = Alipay.objects.filter(out_trade_no=out_trade_no).values().first()
    if recode is not None:
        pay_no = UUIDTools.datetime_random()
        alipay = Alipay.objects.get(pk=recode.get('id'))
        alipay.pay_nos.append(pay_no)
        alipay.save()
    else:
        pay_no = out_trade_no
        Alipay.objects.create(subject=subject,
                              out_trade_no=out_trade_no,
                              total_amount=total_amount,
                              return_url=return_url,
                              notify_url=notify_url,
                              pay_nos=[pay_no],
                              created_by=user_id,
                              updated_by=user_id
                              )

    ali_pay = AliPay(
        appid=APPID,
        app_notify_url=NOTIFY_URL,
        app_private_key_path=PRIVATE_KEY_PATH,
        alipay_public_key_path=ALI_PUB_KEY_PATH,
        debug=True,  # 默认False,
        return_url=return_url
    )

    total_amount = "%.2f" % float(total_amount)
    url = ali_pay.direct_pay(
        subject=subject,
        out_trade_no=pay_no,
        total_amount=total_amount
    )
    # 沙箱环境网关
    # alipay_url = "https://openapi.alipaydev.com/gateway.do?{data}".format(data=url)
    # 正式环境网关
    alipay_url = "https://openapi.alipay.com/gateway.do?{data}".format(data=url)
    return alipay_url


@jsonrpc_method('pay.get_wxpay_url')
def get_wxpay_url(request, out_trade_no, body, total_fee, notify_url, product_id, user_id):
    recode = Wxorder.objects.filter(out_trade_no=out_trade_no).values().first()
    if recode is None:
        Wxorder.objects.create(
            out_trade_no=out_trade_no,
            body=body,
            total_fee=total_fee,
            notify_url=notify_url,
            product_id=product_id,
            created_by=user_id,
            updated_by=user_id
        )

    pay_no = UUIDTools.datetime_random()
    pay = UnifiedOrderPay(WXAPPID, WX_MCH_ID, WX_PAY_KEY)
    response = pay.post(body, pay_no, total_fee,
                        WXPAY_CALLBACK_URL.split('://')[1].split(':')[0], WX_NOTIFY_URL)
    if response and response["return_code"] == "SUCCESS" and response["result_code"] == "SUCCESS":
        wxorder = Wxorder.objects.filter(out_trade_no=out_trade_no).values().first()
        Wxpay.objects.create(
            out_trade_no=out_trade_no,
            pay_no=pay_no,
            code_url=response.get('code_url'),
            nonce_str=response.get('nonce_str'),
            created_by=user_id,
            updated_by=user_id
        )
        return response.get('code_url')


@jsonrpc_method('pay.wx_order_query')
def wx_order_query(request, out_trade_no):
    wxpays = Wxpay.objects.filter(out_trade_no=out_trade_no).values()
    pay = OrderQuery(WXAPPID, WX_MCH_ID, WX_PAY_KEY)
    for wxpay in wxpays:
        response = pay.post(wxpay.get('pay_no'))
        if response and response["return_code"] == "SUCCESS" 
                and response["result_code"] == "SUCCESS":
            trade_state = response["trade_state"]
            if trade_state == "SUCCESS":  # 支付成功
                pay_time = response["time_end"]
                transaction_id = response["transaction_id"]
                Wxorder.objects.filter(out_trade_no=out_trade_no).update(
                    pay_time=time.strftime("%Y-%m-%d %H:%M:%S",
                                           time.strptime(pay_time, "%Y%m%d%H%M%S")),
                    transaction_id=transaction_id
                )
                return {"success": True, "pay_time": pay_time}
    return {"success": False}

4、alipay.py：

# -*- coding: utf-8 -*-

# pip install pycryptodome

from datetime import datetime
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA256
from base64 import b64encode, b64decode
from urllib.parse import quote_plus
from urllib.parse import urlparse, parse_qs
from urllib.request import urlopen
from base64 import decodebytes, encodebytes

import json


class AliPay(object):
    """
    支付宝支付接口
    """

    def __init__(self, appid, app_notify_url, app_private_key_path,
                 alipay_public_key_path, return_url, debug=False):
        self.appid = appid
        self.app_notify_url = app_notify_url
        self.app_private_key_path = app_private_key_path
        self.app_private_key = None
        self.return_url = return_url
        with open(self.app_private_key_path) as fp:
            self.app_private_key = RSA.importKey(fp.read())

        self.alipay_public_key_path = alipay_public_key_path
        with open(self.alipay_public_key_path) as fp:
            self.alipay_public_key = RSA.import_key(fp.read())

        if debug is True:
            self.__gateway = "https://openapi.alipaydev.com/gateway.do"
        else:
            self.__gateway = "https://openapi.alipay.com/gateway.do"

    def direct_pay(self, subject, out_trade_no, total_amount, return_url=None, **kwargs):
        biz_content = {
            "subject": subject,
            "out_trade_no": out_trade_no,
            "total_amount": total_amount,
            "product_code": "FAST_INSTANT_TRADE_PAY",
            # "qr_pay_mode":4
        }

        biz_content.update(kwargs)
        data = self.build_body("alipay.trade.page.pay", biz_content, self.return_url)
        return self.sign_data(data)

    def build_body(self, method, biz_content, return_url=None):
        data = {
            "app_id": self.appid,
            "method": method,
            "charset": "utf-8",
            "sign_type": "RSA2",
            "timestamp": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
            "version": "1.0",
            "biz_content": biz_content
        }

        if return_url is not None:
            data["notify_url"] = self.app_notify_url
            data["return_url"] = self.return_url

        return data

    def sign_data(self, data):
        data.pop("sign", None)
        # 排序后的字符串
        unsigned_items = self.ordered_data(data)
        unsigned_string = "&".join("{0}={1}".format(k, v) for k, v in unsigned_items)
        sign = self.sign(unsigned_string.encode("utf-8"))
        ordered_items = self.ordered_data(data)
        quoted_string = "&".join("{0}={1}".format(k, quote_plus(v)) for k, v in ordered_items)

        # 获得最终的订单信息字符串
        signed_string = quoted_string + "&sign=" + quote_plus(sign)
        return signed_string

    def ordered_data(self, data):
        complex_keys = []
        for key, value in data.items():
            if isinstance(value, dict):
                complex_keys.append(key)

        # 将字典类型的数据dump出来
        for key in complex_keys:
            data[key] = json.dumps(data[key], separators=(',', ':'))

        return sorted([(k, v) for k, v in data.items()])

    def sign(self, unsigned_string):
        # 开始计算签名
        key = self.app_private_key
        signer = PKCS1_v1_5.new(key)
        signature = signer.sign(SHA256.new(unsigned_string))
        # base64 编码，转换为unicode表示并移除回车
        sign = encodebytes(signature).decode("utf8").replace("
", "")
        return sign

    def _verify(self, raw_content, signature):
        # 开始计算签名
        key = self.alipay_public_key
        signer = PKCS1_v1_5.new(key)
        digest = SHA256.new()
        digest.update(raw_content.encode("utf8"))
        if signer.verify(digest, decodebytes(signature.encode("utf8"))):
            return True
        return False

    def verify(self, data, signature):
        if "sign_type" in data:
            sign_type = data.pop("sign_type")
        # 排序后的字符串
        unsigned_items = self.ordered_data(data)
        message = "&".join(u"{}={}".format(k, v) for k, v in unsigned_items)
        return self._verify(message, signature)


if __name__ == "__main__":
    alipay = AliPay(
        appid="2016081500252338",
        app_notify_url="http://projectsedus.com/",
        app_private_key_path="keys/private_2048.txt",
        alipay_public_key_path="keys/alipay_key_2048.txt",  # 支付宝的公钥，验证支付宝回传消息使用，不是你自己的公钥,
        debug=True,  # 默认False,
        return_url="http://192.168.247.129:8000/"
    )

    url = alipay.direct_pay(
        subject="测试订单",
        out_trade_no="20170202126666",
        total_amount=1000
    )
    re_url = "https://openapi.alipaydev.com/gateway.do?{data}".format(data=url)
    print(re_url)

5、wxpay.py：

# -*- coding=utf-8 -*-

import time
import json
import hashlib
import requests

from pay.utils import (smart_str, dict_to_xml, calculate_sign, random_str,
                       post_xml, xml_to_dict, validate_post_xml, format_url)

# from local_settings import appid, mch_id, api_key


OAUTH2_AUTHORIZE_URL = "https://open.weixin.qq.com/connect/oauth2/authorize?%s"
OAUTH2_ACCESS_TOKEN_URL = "https://api.weixin.qq.com/sns/oauth2/access_token?%s"


class WeiXinPay(object):
    def __init__(self, appid, mch_id, api_key):
        self.appid = appid  # 微信公众号身份的唯一标识。审核通过后，在微信发送的邮件中查看
        self.mch_id = mch_id  # 受理商ID，身份标识
        self.api_key = api_key  # 商户支付密钥Key。审核通过后，在微信发送的邮件中查看
        self.common_params = {
            "appid": self.appid,
            "mch_id": self.mch_id,
        }
        self.params = {}
        self.url = ""
        self.trade_type = ""

    def set_params(self, **kwargs):
        self.params = {}
        for (k, v) in kwargs.items():
            self.params[k] = smart_str(v)

        self.params["nonce_str"] = random_str(32)
        if self.trade_type:
            self.params["trade_type"] = self.trade_type
        self.params.update(self.common_params)

    def post_xml(self):
        sign = calculate_sign(self.params, self.api_key)
        xml = dict_to_xml(self.params, sign)
        response = post_xml(self.url, xml)
        return xml_to_dict(response.text)

    def valiate_xml(self, xml):
        return validate_post_xml(xml, self.appid, self.mch_id, self.api_key)

    def get_error_code_desc(self, error_code):
        error_desc = {
            "SYSTEMERROR": u"接口后台错误",
            "INVALID_TRANSACTIONID": u"无效 transaction_id",
            "PARAM_ERROR": u"提交参数错误",
            "ORDERPAID": u"订单已支付",
            "OUT_TRADE_NO_USED": u"商户订单号重复",
            "NOAUTH": u"商户无权限",
            "NOTENOUGH": u"余额丌足",
            "NOTSUPORTCARD": u"不支持卡类型",
            "ORDERCLOSED": u"订单已关闭",
            "BANKERROR": u"银行系统异常",
            "REFUND_FEE_INVALID": u"退款金额大亍支付金额",
            "ORDERNOTEXIST": u"订单不存在",
        }
        return error_desc.get(error_code.strip().upper(), u"未知错误")


class UnifiedOrderPay(WeiXinPay):
    """发送预支付单"""

    def __init__(self, appid, mch_id, api_key):
        super(UnifiedOrderPay, self).__init__(appid, mch_id, api_key)
        self.url = "https://api.mch.weixin.qq.com/pay/unifiedorder"
        self.trade_type = "NATIVE"

    def post(self, body, out_trade_no, total_fee, spbill_create_ip, notify_url, **kwargs):
        tmp_kwargs = {
            "body": body,
            "out_trade_no": out_trade_no,
            "total_fee": total_fee,
            "spbill_create_ip": spbill_create_ip,
            "notify_url": notify_url,
        }
        tmp_kwargs.update(**kwargs)
        self.set_params(**tmp_kwargs)
        return self.post_xml()[1]


class OrderQuery(WeiXinPay):
    """订单状态查询"""

    def __init__(self, appid, mch_id, api_key):
        super(OrderQuery, self).__init__(appid, mch_id, api_key)
        self.url = "https://api.mch.weixin.qq.com/pay/orderquery"

    def post(self, out_trade_no):
        self.set_params(out_trade_no=out_trade_no)
        return self.post_xml()[1]


class JsAPIOrderPay(UnifiedOrderPay):
    """H5页面的Js调用类"""

    def __init__(self, appid, mch_id, api_key, app_secret):
        super(JsAPIOrderPay, self).__init__(appid, mch_id, api_key)
        self.app_secret = app_secret
        self.trade_type = "JSAPI"

    def create_oauth_url_for_code(self, redirect_uri):
        url_params = {
            "appid": self.appid,
            "redirect_uri": redirect_uri,  # 一般是回调当前页面
            "response_type": "code",
            "scope": "snsapi_base",
            "state": "STATE#wechat_redirect"
        }
        url = format_url(url_params)
        return OAUTH2_AUTHORIZE_URL % url

    def _create_oauth_url_for_openid(self, code):
        url_params = {
            "appid": self.appid,
            "secret": self.app_secret,
            "code": code,
            "grant_type": "authorization_code",
        }
        url = format_url(url_params)
        return OAUTH2_ACCESS_TOKEN_URL % url

    def _get_oauth_info(self, code):
        """
        获取OAuth2的信息：access_token、expires_in、refresh_token、openid、scope
        返回结果为字典，可使用["xxx"]或.get("xxx", None)的方式进行读取
        """
        url = self._create_oauth_url_for_openid(code)
        response = requests.get(url)
        return response.json() if response else None

    def _get_openid(self, code):
        oauth_info = self._get_oauth_info(code)
        if oauth_info:
            return oauth_info.get("openid", None)
        return None

    def _get_json_js_api_params(self, prepay_id):
        js_params = {
            "appId": self.appid,
            "timeStamp": "%d" % time.time(),
            "nonceStr": random_str(32),
            "package": "prepay_id=%s" % prepay_id,
            "signType": "MD5",
        }
        js_params["paySign"] = calculate_sign(js_params, self.api_key)
        return js_params

    def post(self, body, out_trade_no, total_fee, spbill_create_ip, notify_url, code):
        if code:
            open_id = self._get_openid(code)
            if open_id:
                # 直接调用基类的post方法查询prepay_id，如果成功，返回一个字典
                unified_order = super(JsAPIOrderPay, self).post(body, out_trade_no, total_fee, spbill_create_ip,
                                                                notify_url, open_id=open_id)
                if unified_order:
                    prepay_id = unified_order.get("prepay_id", None)
                    if prepay_id:
                        return self._get_json_js_api_params(prepay_id)
        return None

6、utils.py：

# -*- coding=utf-8 -*-
import hashlib
import re
import types
from random import Random
import requests
import thriftpy

from django.conf import settings
from django.core.exceptions import FieldDoesNotExist
from django.db import models
from django.db.models.fields.reverse_related import ForeignObjectRel
from rest_framework.pagination import PageNumberPagination
from thriftpy.rpc import make_client

from pay.exception_handler import ForeignObjectRelDeleteError, ModelDontHaveIsActiveFiled, logger


def smart_str(s, encoding='utf-8', strings_only=False, errors='strict'):
    """
    Returns a bytestring version of 's', encoded as specified in 'encoding'.
    If strings_only is True, don't convert (some) non-string-like objects.
    """
    if strings_only and isinstance(s, (types.NoneType, int)):
        return s
    if not isinstance(s, str):
        try:
            return str(s)
        except UnicodeEncodeError:
            if isinstance(s, Exception):
                # An Exception subclass containing non-ASCII data that doesn't
                # know how to print itself properly. We shouldn't raise a
                # further exception.
                return ' '.join([smart_str(arg, encoding, strings_only,
                                           errors) for arg in s])
            return unicode(s).encode(encoding, errors)
    elif s and encoding != 'utf-8':
        return s.decode('utf-8', errors).encode(encoding, errors)
    else:
        return s


def format_url(params, api_key=None):
    url = "&".join(['%s=%s' % (key, smart_str(params[key])) for key in sorted(params)])
    if api_key:
        url = '%s&key=%s' % (url, api_key)
    return url


def calculate_sign(params, api_key):
    # 签名步骤一：按字典序排序参数, 在string后加入KEY
    url = format_url(params, api_key)
    # 签名步骤二：MD5加密, 所有字符转为大写
    return hashlib.md5(url.encode('utf-8')).hexdigest().upper()


def dict_to_xml(params, sign):
    xml = ["<xml>", ]
    for (k, v) in params.items():
        if (v.isdigit()):
            xml.append('<%s>%s</%s>' % (k, v, k))
        else:
            xml.append('<%s><![CDATA[%s]]></%s>' % (k, v, k))
    xml.append('<sign><![CDATA[%s]]></sign></xml>' % sign)
    return ''.join(xml)


def xml_to_dict(xml):
    if xml[0:5].upper() != "<XML>" and xml[-6].upper() != "</XML>":
        return None, None

    result = {}
    sign = None
    content = ''.join(xml[5:-6].strip().split('
'))

    pattern = re.compile(r"<(?P<key>.+)>(?P<value>.+)</(?P=key)>")
    m = pattern.match(content)
    while (m):
        key = m.group("key").strip()
        value = m.group("value").strip()
        if value != "<![CDATA[]]>":
            pattern_inner = re.compile(r"<![CDATA[(?P<inner_val>.+)]]>")
            inner_m = pattern_inner.match(value)
            if inner_m:
                value = inner_m.group("inner_val").strip()
            if key == "sign":
                sign = value
            else:
                result[key] = value

        next_index = m.end("value") + len(key) + 3
        if next_index >= len(content):
            break
        content = content[next_index:]
        m = pattern.match(content)

    return sign, result


def validate_post_xml(xml, appid, mch_id, api_key):
    sign, params = xml_to_dict(xml)
    if (not sign) or (not params):
        return None

    remote_sign = calculate_sign(params, api_key)
    if sign != remote_sign:
        return None

    if params["appid"] != appid or params["mch_id"] != mch_id:
        return None

    return params


def random_str(randomlength=8):
    chars = 'abcdefghijklmnopqrstuvwxyz0123456789'
    random = Random()
    return "".join([chars[random.randint(0, len(chars) - 1)] for i in range(randomlength)])


def post_xml(url, xml):
    return requests.post(url, data=xml.encode('utf-8'), verify=False)


class UnActiveModelMixin(object):
    """
    删除一个对象，并不真删除，级联将对应外键对象的is_active设置为false，需要外键对象都有is_active字段.
    """

    def perform_destroy(self, instance):
        rel_fileds = [f for f in instance._meta.get_fields() if isinstance(f, ForeignObjectRel)]

        links = [f.get_accessor_name() for f in rel_fileds]

        for link in links:
            manager = getattr(instance, link, None)
            if not manager:
                continue
            if isinstance(manager, models.Model):
                if hasattr(manager, 'is_active') and manager.is_active:
                    manager.is_active = False
                    manager.save()
                    raise ForeignObjectRelDeleteError(u'{} 上有关联数据'.format(link))
            else:
                if not manager.count():
                    continue
                try:
                    manager.model._meta.get_field('is_active')
                    manager.filter(is_active=True).update(is_active=False)
                except FieldDoesNotExist as ex:
                    # 理论上，级联删除的model上面应该也有is_active字段，否则代码逻辑应该有问题
                    logger.warn(ex)
                    raise ModelDontHaveIsActiveFiled(
                        '{}.{} 没有is_active字段, 请检查程序逻辑'.format(
                            manager.model.__module__,
                            manager.model.__class__.__name__
                        ))
        instance.is_active = False
        instance.save()

    def get_queryset(self):
        return self.queryset.filter(is_active=True)


class StandardResultsSetPagination(PageNumberPagination):
    page_size_query_param = 'size'