关于Flask Config文档

class Config:
    SECRET_KEY = os.environ.get('SECRET_KEY') or 'hard to guess string'
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    MAIL_SERVER = 'smtp.126.com'
    MAIL_PORT = 25
    MAIL_USE_TLS = True
    MAIL_USERNAME = json_dict['MAIL_USERNAME']
    MAIL_PASSWORD = json_dict['MAIL_PASSWORD']
    FLASK_MAIL_SUBJECT_PREFIX = '[FLASKY]'
    FLASK_MAIL_SENDER = 'Flasky Admin ' + json_dict['EMAIL_ADDRESS']


class DevelopmentConfig(Config):
    DEBUG = True
    SQLALCHEMY_DATABASE_URI = "mysql+pymysql://root:" + json_dict['MAIL_PASSWORD'] + "@localhost:3306/robot"



config = {
    'development': DevelopmentConfig,
    'testing': TestingConfig,
    'production': ProductionConfig,
    'default': DevelopmentConfig
}

在用python flask编写网页，运行时候遇到以下的错误：

 File "C:\Flask\config.py", line 26, in <module>
    'testing': TestingConfig,
NameError: name 'TestingConfig' is not defined

为什么这里的'TestingConfig' is not defined说没有被定义。因为'TestingConfig'在这里是一个对象，是一个变量。Python是动态的，这里的对象和变量不能没有初始化或者定义！

这就是为什么config这个字典要放到在最后的原因！