dmjio
Eliminate (really unsafe) record fields on data types with variants.
I just converted an application from the previous stripe library, and in general things have been good, but I have some pretty serious concerns about safety. In particular, I just saw an error in production due to this problem. Essentially, record field accessors on data types with variants are really unsafe. The particular one that I hit was on Customer - I was converting code, and the other stripe library had only one Customer variant, and had a (perfectly safe and good) customerId record field. So the code compiled, and then at runtime, it got passed a DeletedCustomer, and exploded.
To be honest, I think having these be variants at all is pretty bizarre. I would much prefer if DeletedCustomer was it's own type, and if an endpoint can return either, then make it be Either. Having Customer sometimes not really be customer is odd.
There is a nuance (specifically for customers, and only customers), that retrieving deleted customer records don't 404, they stick around. I agree that these partial functions need to be removed and the current solution is not ideal. @stepkut's changes still need to be merged, and I believe they remedy this situation. It's been hard to get a breather from work, and the merge is huge. I apologize for this, and plan to make the changes asap.
@dbp, thought of a solution to this. Then make all customer retrieval functions use this.
{-# LANGUAGE FlexibleInstances #-}
import Control.Applicative
import Data.Aeson
instance FromJSON (Either DeletedCustomer Customer) where
parseJSON (Object o) = do
result <- o .: "deleted"
case result of
True -> Left <$> (DeletedCustomer <$> parseJSON o)
False -> Right <$> (Customer <$> parseJSON o)
This issue is a bit of a pickle. I've implemented:
newtype CustomerResult = CustomerResult (Either DeletedCustomer Customer)
deriving (LotsOfThings)
All the tests pass except for one. For some reason removing a discount on a customer actually deletes the customer. Still pondering...
For some reason removing a discount on a customer actually deletes the customer
wot
