REST framework now has more explicit and clear control over validating empty values for fields.
Previously the meaning of the `required=False` keyword argument was underspecified. In practice its use meant that a field could either be not included in the input, or it could be included, but be `None`.
Previously the meaning of the `required=False` keyword argument was underspecified. In practice its use meant that a field could either be not included in the input, or it could be included, but be `None` or the empty string.
We now have a better separation, with separate `required` and `allow_none` arguments.
We now have a better separation, with separate `required`, `allow_none` and `allow_blank` arguments.
The following set of arguments are used to control validation of empty values:
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@@ -519,7 +519,7 @@ The following set of arguments are used to control validation of empty values:
Typically you'll want to use `required=False` if the corresponding model field has a default value, and additionally set either `allow_none=True` or `allow_blank=True` if required.
The `default` argument is there if you need it, but you'll more typically want defaults to be set on model fields, rather than serializer fields.
The `default` argument is also available and always implies that the field is not required to be in the input. It is unnecessary to use the `required` argument when a default is specified, and doing so will result in an error.
