Hi James,

On Mon, 31 Dec 2018 10:24:39 -0800
James Bennett <ubernost...@gmail.com> wrote:

> The basic problem is that, to take the example in the ticket, if I
> were to issue a request like "/students/?year=FR", and the view were
> to read that "year" param and try to filter on it, it would fail --
> the string "FR" will not compare equal to the enum member "FR". So I
> couldn't easily use that to filter for students whose year is
> Student.YearInSchool.Freshman.

Like so:

        >>> class SchoolYear(Enum):
        ...   FRESHMAN = 'FR'
        ...   JUNIOR   = 'JR'
        ... 
        >>> SchoolYear.FRESHMAN == 'FR'
        False

>
> 
> This is a deliberate design decision in Python's enums which,
> unfortunately, makes them unsuitable for the kinds of things people
> would commonly use them for in Django; only the special one-off
> enum.IntEnum has members that actually are comparable to a base
> Python type, and writing special-case enum variants for other types
> to try to enable comparability would be a pain.
> 

The actual definition of IntEnum is

        class IntEnum(int, Enum):
                """Enum where members are also (and must be) ints"""

(it turns out that you don't need a 'pass' statement when you have a
docstring). And indeed,

        >>> class SchoolYear(str, Enum):
        ...   FRESHMAN = 'FR'
        ...   JUNIOR   = 'JR'
        ... 
        >>> SchoolYear.FRESHMAN == 'FR'
        True

All it takes is adding the base Python type as a base of your
enumeration type.

Shai.

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