Restore str representation conversion logic removed in 2.1.0

[johnthagen]

Closes #124

• Reverts part of 0eabdb4

• Fix DeprecationWarning in test usage of ugettext_lazy

[johnthagen]

@akx Would you mind taking a look? Might need a 2.2.1 to restore capability with parts of the DRF ecosystem.

[gsakkis]

I'm not quite sure this is a bug, or even if it is, that this is the right fix. Looking at the to_representation implementations for DRF fields, afaict none of them does validation of the input value. ChoiceField in particular returns the input value if it doesn't match any of the choices:

    def to_representation(self, value):
        if value in ('', None):
            return value
        return self.choice_strings_to_values.get(str(value), value)

In any case, a related unit test should be added; this was the reason it was removed at 0eabdb4 in the first place.

[johnthagen]

In any case, a related unit test should be added; this was the reason it was removed at 0eabdb4 in the first place.

Good point. I have added several unit tests in 7164aa1.

[gsakkis]

FWIW to keep the same semantics with ChoiceField my fix would be:

if not isinstance(instance, self.enum):
    return instance
...
# rest left as is

I'm not a DRF expert but I don't think to_representation should be raising an exception for invalid values.

[akx]

Good morning!

I think this is a good enough fix for 2.1.1 as a bug fix. We could take a look at whether to simplify things for a future version.

Merging, thanks.

EDIT: Released in 2.1.1.

[johnthagen]

@akx Confirmed that 2.1.1 is working again in our production app. Thanks!