pip install wechatpy

WECHAT = {
    'APPID': 'appid',               # 小程序ID
    'APPSECRET': 'appsecret',			# 小程序SECRET
    'MCH_ID': 'mch_id',                   # 商戶號
    'TOTAL_FEE': '1',                      # 總金額， 單位為“分”
    'SPBILL_CREATE_IP': '127.0.0.1',              # 終端IP
    'NOTIFY_URL': 'http://127.0.0.1:8000/wechat/payNotify/',     # 通知地址
    'TRADE_TYPE': 'JSAPI',                   # 交易類型
    'MERCHANT_KEY': 'merchant_key',     # 商戶KEY
    'BODY': '商品描述',                # 商品描述
}

from django.http import HttpResponse
import requests
import json
from django.conf import settings
from wechatpy.pay import WeChatPay
from app_base.base_viewset import BaseAPIView
from rest_framework import permissions
from lxml import etree as et
from rest_framework import status


class WeChatPayViewSet(BaseAPIView):
  """
  通過小程序前端 wx.login() 接口獲取臨時登錄憑證 code
  將 code 作為參數傳入，調用 get_user_info() 方法獲取 openid
  """

  def get_user_info(self, js_code):
    """
    使用 臨時登錄憑證code 獲取 session_key 和 openid 等
    支付部分僅需 openid，如需其他用戶信息請按微信官方開發文檔自行解密
    """
    req_params = {
      'appid': settings.WECHAT['APPID'],
      'secret': settings.WECHAT['APPSECRET'],
      'js_code': js_code,
      'grant_type': 'authorization_code',
    }
    user_info = requests.get('https://api.weixin.qq.com/sns/jscode2session',
                 params=req_params, timeout=3, verify=False)
    return user_info.json()

  def get(self, request):
    code = request.GET.get("code", None)
    openid = self.get_user_info(code)['openid']

    pay = WeChatPay(settings.WECHAT['APPID'], settings.WECHAT['MERCHANT_KEY'], settings.WECHAT['MCH_ID'])
    order = pay.order.create(
      trade_type=settings.WECHAT['TRADE_TYPE'], # 交易類型，小程序取值：JSAPI
      body=settings.WECHAT['BODY'], # 商品描述，商品簡單描述
      total_fee=settings.WECHAT['TOTAL_FEE'], # 標價金額，訂單總金額，單位為分
      notify_url=settings.WECHAT['NOTIFY_URL'], # 通知地址，異步接收微信支付結果通知的回調地址，通知url必須為外網可訪問的url，不能攜帶參數。
      user_id=openid # 用戶標識，trade_type=JSAPI，此參數必傳，用戶在商戶appid下的唯一標識。
    )
    wxpay_params = pay.jsapi.get_jsapi_params(order['prepay_id'])
    return HttpResponse(json.dumps(wxpay_params))


class WeChatPayNotifyViewSet(BaseAPIView):
  permission_classes = (permissions.AllowAny, )

  def get(self, request):
    _xml = request.body
    # 拿到微信發送的xml請求 即微信支付后的回調內容
    xml = str(_xml, encoding="utf-8")
    print("xml", xml)
    return_dict = {}
    tree = et.fromstring(xml)
    # xml 解析
    return_code = tree.find("return_code").text
    try:
      if return_code == 'FAIL':
        # 官方發出錯誤
        return_dict['message'] = '支付失敗'
        # return Response(return_dict, status=status.HTTP_400_BAD_REQUEST)
      elif return_code == 'SUCCESS':
        # 拿到自己這次支付的 out_trade_no
        _out_trade_no = tree.find("out_trade_no").text
        # TODO 這里省略了 拿到訂單號后的操作 看自己的業務需求
    except Exception as e:
      pass
    finally:
      return HttpResponse(return_dict, status=status.HTTP_200_OK)

# -*- coding: utf-8 -*-
from rest_framework.authentication import TokenAuthentication
from rest_framework.views import APIView
from rest_framework import permissions

__author__ = 'JayChen'


class BaseAPIView(APIView):
  permission_classes = (permissions.IsAuthenticated,)
  # authentication_classes = (TokenAuthentication,)

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

__author__ = 'JayChen'

from django.conf.urls import url
from rest_framework.urlpatterns import format_suffix_patterns
from pay import views

app_name = 'pay'
urlpatterns = [
  # 微信小程序支付
  url(r'^pay/', views.WeChatPayViewSet.as_view(), name='pay'),
  # 支付結果回調
  url(r'^payNotify/', views.WeChatPayNotifyViewSet.as_view(), name='pay_notify'),
]

from django.contrib import admin
from django.urls import path, include
from rest_framework_jwt.views import obtain_jwt_token

urlpatterns = [
  path('admin/', admin.site.urls),
  path('token_auth/', obtain_jwt_token, name='jwt_token'),
  path('user/', include('auth_jwt.urls')),
  
  path('wechat/', include('pay.urls')), # 微信支付相關
]

{
  "appId": "wx14b75285dfe1",
  "timeStamp": "1595228",
  "nonceStr": "1Wtu5lKb6T3fJLiNzc09ay2Z",
  "signType": "MD5",
  "package": "prepay_id=wx02158826854686197390000",
  "paySign": "89599A11E051D3B20FF57"
}