The `api_settings` object will check for any user-defined settings, and otherwise fall back to the default values. Any setting that uses string import paths to refer to a class will automatically import and return the referenced class, instead of the string literal.
A list or tuple of authentication classes, that determines the default set of authenticators used when accessing the `request.user` or `request.auth` properties.
A list or tuple of permission classes, that determines the default set of permissions checked at the start of a view. Permission must be granted by every class in the list.
The value that should be used for `request.version` when no versioning information is present.
Default: `None`
#### ALLOWED_VERSIONS
If set, this value will restrict the set of versions that may be returned by the versioning scheme, and will raise an error if the provided version if not in this set.
Determines whether a single or multiple challenges are presented in the `WWW-Authenticate` header.
This should be set to `'first'` (the default value) or `'all'`. When set to `'first'`, the `WWW-Authenticate` header will be set to an appropriate challenge for the first authentication scheme in the list.
When set to `'all'`, a comma-separated list of the challenge for all specified authentication schemes will be used instead (following the [syntax specification](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/WWW-Authenticate)).
The format of any of these renderer classes may be used when constructing a test request, for example: `client.post('/users', {'username': 'jamie'}, format='json')`
The name of a URL parameter that may be used to override the default content negotiation `Accept` header behavior, by using a `format=…` query parameter in the request URL.
The name of a parameter in the URL conf that may be used to provide a format suffix. This setting is applied when using `format_suffix_patterns` to include suffixed URL patterns.
A format string that should be used by default for rendering the output of `DateTimeField` serializer fields. If `None`, then `DateTimeField` serializer fields will return Python `datetime` objects, and the datetime encoding will be determined by the renderer.
A format string that should be used by default for rendering the output of `DateField` serializer fields. If `None`, then `DateField` serializer fields will return Python `date` objects, and the date encoding will be determined by the renderer.
A format string that should be used by default for rendering the output of `TimeField` serializer fields. If `None`, then `TimeField` serializer fields will return Python `time` objects, and the time encoding will be determined by the renderer.
Both styles conform to [RFC 4627][rfc4627], and are syntactically valid JSON. The unicode style is preferred as being more user-friendly when inspecting API responses.
When set to `True`, JSON rendering and parsing will only observe syntactically valid JSON, raising an exception for the extended float values (`nan`, `inf`, `-inf`) accepted by Python's `json` module. This is the recommended setting, as these values are not generally supported. e.g., neither Javascript's `JSON.Parse` nor PostgreSQL's JSON data type accept these values.
When set to `False`, JSON rendering and parsing will be permissive. However, these values are still invalid and will need to be specially handled in your code.
When returning decimal objects in API representations that do not support a native decimal type, it is normally best to return the value as a string. This avoids the loss of precision that occurs with binary floating point implementations.
When set to `True`, the serializer `DecimalField` class will return strings instead of `Decimal` objects. When set to `False`, serializers will return `Decimal` objects, which the default JSON encoder will return as floats.
**The following settings are used to generate the view names and descriptions, as used in responses to `OPTIONS` requests, and as used in the browsable API.**
#### VIEW_NAME_FUNCTION
A string representing the function that should be used when generating view names.
This should be a function with the following signature:
*`self`: The view instance. Typically the name function would inspect the name of the class when generating a descriptive name, by accessing `self.__class__.__name__`.
If the view instance inherits `ViewSet`, it may have been initialized with several optional arguments:
A string representing the function that should be used when generating view descriptions.
This setting can be changed to support markup styles other than the default markdown. For example, you can use it to support `rst` markup in your view docstrings being output in the browsable API.
This should be a function with the following signature:
*`self`: The view instance. Typically the description function would inspect the docstring of the class when generating a description, by accessing `self.__class__.__doc__`
*`html`: A boolean indicating if HTML output is required. `True` when used in the browsable API, and `False` when used in generating `OPTIONS` responses.
If the view instance inherits `ViewSet`, it may have been initialized with several optional arguments:
*`description`: A description explicitly provided to the view in the viewset. Typically, this is set by extra viewset `action`s, and should be used as-is.
A string representing the function that should be used when returning a response for any given exception. If the function returns `None`, a 500 error will be raised.
This setting can be changed to support error responses other than the default `{"detail": "Failure..."}` responses. For example, you can use it to provide API responses like `{"errors": [{"message": "Failure...", "code": ""} ...]}`.
This should be a function with the following signature:
An integer of 0 or more, that may be used to specify the number of application proxies that the API runs behind. This allows throttling to more accurately identify client IP addresses. If set to `None` then less strict IP matching will be used by the throttle classes.
