come up with a nicer way of handling enum fields at the diesel level

[jrheard]

right now i'm using newtype constants to do enum-y things, but i'd prefer it if i could use enums. i want to be able to work with enum variants in rust and have diesel automatically translate them to corresponding string values and back.

i tried diesel-derive-enum and manually implementing tosql/fromsql myself, but didn't have a good time with either one. maybe i'll have better luck if i try that again, or maybe there's some other approach i'm missing.

[jrheard]

this looks really promising: https://github.com/diesel-rs/diesel/blob/master/examples/postgres/custom_types/src/model.rs