Use of deserialize_any breaks deserialization with bincode

[jekirl]

Currently the deserialize implementation calls the serde deserialize_any function, which breaks Decimal serialization with non-self describing formats like bincode [0].

When implementing Deserialize, you should avoid relying on Deserializer::deserialize_any unless you need to be told by the Deserializer what type is in the input. Know that relying on Deserializer::deserialize_any means your data type will be able to deserialize from self-describing formats only, ruling out Bincode and many others.

There are two possible easy fixes:

• Replace deserialize_any with deserialize_str
• Simply have Decimal derive Serialize, Deserialize

[0] https://serde.rs/impl-deserialize.html

[paupino]

Thanks for that write up; I'll take a look into it.

I'm a little reluctant to simply replace with deserialize_str at risk of breaking:

{
   "amount": 100
}

This may, however, be a compromise to support bincode etc. I'll do some further investigation.

[paupino]

Interestingly, simply changing it to deserialize_str works for the existing tests. The only type it won't do is:

{
  "amount": 100.00
}

I'll push in a change for the above now and create a new ticket for float support since it was something that didn't work before.

[Palmik]

Hi. Thanks for this crate. The deserialize_str was swapped back for deserialize_any in this commit so bincode no longer works by default.

[paupino]

I'll look into this a bit some more. I may try and wrap either this or the any into a feature so that it gives library consumers the opportunity to select behavior as needed.