Remove settings type check in authentication tuple to prevent from failing in LazySettings

[fronbasal]

Currently, django-mjml checks for the proper type (str) in the auth tuple in HTTP_SERVERS. Sadly this does not work in a LazySettings environment (django-configurations). This PR removes the assertion of type for the authentication tuple to make this package compatible with django-configurations.

Example:

MJML_BACKEND_MODE = 'httpserver'
MJML_APPLICATION_ID = values.SecretValue()
MJML_SECRET_KEY = values.SecretValue()
MJML_HTTPSERVERS = [
        {
            'URL': 'https://api.mjml.io/v1/render',  # official MJML API
            'HTTP_AUTH': (MJML_APPLICATION_ID, MJML_SECRET_KEY), # won't evaluate to type str directly
        },
]

[liminspace]

@fronbasal why can't you just use (str(MJML_APPLICATION_ID), str(MJML_SECRET_KEY)) in your case?

[fronbasal]

@liminspace That sadly does not work due to the evaluation time of the variable, which is done at access time (when evaluation settings.MJML_APPLICATION_ID, for example). Therefore it won't evaluate to str/is not castable to str.

[liminspace]

@fronbasal can you show the fill example of your using django-configurations in your project?

[fronbasal]

Sure, no problem.

class Common(Configuration):
    MJML_BACKEND_MODE = "cmd"
    MJML_APPLICATION_ID = values.SecretValue()
    MJML_SECRET_KEY = values.SecretValue()
    MJML_HTTPSERVERS = [
        {
            "URL": "https://api.mjml.io/v1/render",  # official MJML API
            "HTTP_AUTH": (MJML_APPLICATION_ID, MJML_SECRET_KEY),
        },
    ]

The .env file then specifies both SecretValue() variables. At runtime the value won't hold any value, because it is lazily evaluated thus only when accessing the setting (getattr(settings, "MJML_SECRET_KEY")) it will evaluate to the actual secret key. By checking the type() at runtime it will break with django-configurations, though.

[liminspace]

@fronbasal try to use property (https://django-configurations.readthedocs.io/en/stable/patterns/#property-settings):

class Common(Configuration):
    MJML_BACKEND_MODE = "cmd"
    MJML_APPLICATION_ID = values.SecretValue()
    MJML_SECRET_KEY = values.SecretValue()

    @property
    def MJML_HTTPSERVERS(self):
        return [
            {
                "URL": "https://api.mjml.io/v1/render",  # official MJML API
                "HTTP_AUTH": (self.MJML_APPLICATION_ID, self.MJML_SECRET_KEY),
            },
        ]

[fronbasal]

Oh - didn't catch that! Thank you, nice hint. Thank you for the good work.