安装Braintree Python模块（braintree==3.45.0）

一、项目的settings.py文件添加下列内容：

# Braintree settings
BRAINTREE_MERCHANT_ID = '保密'
BRAINTREE_PUBLIC_KEY = '保密'
BRAINTREE_PRIVATE_KEY = '保密'
from braintree import Configuration, Environment
Configuration.configure(
    Environment.parse_environment("sandbox"),  # 这一句重点，千万別写成 Environment.Sandbox
    # Environment.parse_environment("product"),
    BRAINTREE_MERCHANT_ID,
    BRAINTREE_PUBLIC_KEY,
    BRAINTREE_PRIVATE_KEY
)

二、Environment.parse_environment("sandbox"),  这一句重点，千万別写成 Environment.Sandbox ，

原因如下：

1、ctrl+鼠标左键点击上面代码的configure（参数1，参数2，参数3，参数4），会发现 参数1 要填 environment，

2、为了找到 environment ，

ctrl+鼠标左键点击上面代码的Environment，

会发现类Environment里的函数  def parse_environment(environment),  返回值是  Environment.All[environment]，

正好 Environment.All["sandbox"] = Environment.Sandbox 

@staticmethod
    def parse_environment(environment):
        if isinstance(environment, Environment) or environment is None:
            return environment
        try:
            return Environment.All[environment]
        # ...............................
#........................................
Environment.All = {
    "development": Environment.Development,
    "integration": Environment.Development,
    "qa": Environment.QA,
    "sandbox": Environment.Sandbox,
    "production": Environment.Production
}