marshalling nested enums from python strings raises a TypeError

[software-dov]

This requires marshaling from python structures.

Minimal reproduction:

import proto

class Zone(proto.Enum):
    LITTORAL = 1
    MESOPELAGIC = 2
    ABYSSAL = 3
    HADEAN = 4

class Squid(proto.Message):
    zone = proto.Field(Zone, number=1)

class Trawl(proto.Message):
    squids = proto.RepeatedField(Squid, number=1)   # Note: this indirection with the nested field
                                                    # is necessary to trigger the exception.
                                                    # Setting the field in an existing message accepts strings AND
                                                    # checks for valid variants.
                                                    # Similarly, constructing a message directly with a top level 
                                                    # enum field kwarg passed as a string is also handled correctly, i.e.
                                                    # s = Squid(zone="ABYSSAL")
                                                    # does NOT raise an exception.

t = Trawl(squids=[{"zone": "HADEAN"}])

generates

TypeError: 'HADEAN' has type str, but expected one of: int, long

This is related to #52, and most of the implementation will probably be shared.

[software-dov]

A workaround is to not use strings directly but instead to use Enum class attributes.
E.g., assuming the above example class definitions,

t = Trawl(squids=[{"zone": Zone.HADEAN}, {"zone": Zone.LITTORAL}])

[hkdevandla]

Making this as p3 considering that there is a workaround. @software-dov , adjust this if you disagree. thanks!

[software-dov]

There is a workaround, and the issue is fixed by #107

[software-dov]

Fixe