Using custom any resolver to StargateQuerier

[dadamu]

Context

Currently StargateQuerier is using default any resolver provided by codec.Codec, which unpacks Any type to the underlying structure then builds the JSON message for wasmvm. That makes parsing the proto message difficult since parsing underlying structure into Any requires a custom decoder inside contract.

The definition of default codec any resolver can be traced here:
https://github.com/cosmos/cosmos-sdk/blob/13e61bd0c5c7950d137bbdfb171f95d87179ed29/codec/proto_codec.go#L148
https://github.com/cosmos/cosmos-sdk/blob/13e61bd0c5c7950d137bbdfb171f95d87179ed29/codec/json.go#L16

For example, Desmos profiles is a Any proto message, the json pass to wasmvm is:

{
    "@type": "/desmos.profiles.v3.Profile",
    "dtag": "abc",
    "nickname": "abc",
    "bio": "abc",
    ...other fields
}

Instead of a Any JSON can be easily deserialized

{
    "@type": "/desmos.profiles.v3.Profile",
    "value": "<bas64 encoded of desmos Profile>"
}

As a result, it is not easy to deserialize the Any structure in Rust like:

pub struct Any {
     #[prost(string, tag = "1")]
    pub type_url: ::prost::alloc::string::String,
    #[prost(bytes = "vec", tag = "2")]
    pub value: ::prost::alloc::vec::Vec<u8>,
}

impl<'de> Deserialize<'de> for Any {
   fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: serde::Deserializer<'de>,
    {
       logic of deserialize the JSON into Any
    }
}

Solution

The solution can be implementing a custom any resolver to unpack to Any JSON without underlying structure, it would be like the following commit, then the Any deserialization will be easy in contract side:
https://github.com/desmos-labs/wasmd/commit/b7700dfcc403b58c9702f0c45f4016b9668a287e

What do you think? I can create a pull request if you think it is worth to do.

Edited: 05:00 UTC +0, June 20, 2023

[webmaster128]

Instead of a proper any JSON format like

This is only a smaller point of the whole problem, but please note that in https://protobuf.dev/programming-guides/proto3/#json the flattening of the Any in JSON is specified. This might not be the best way to use it in a contract, but is correct from the standardization point of view.

[dadamu]

@webmaster128 Thanks for the reference! I see and fixed the content.

[alpe]

Changing the response encoding would be a breaking change for existing contracts. We can not simply do this without a lot of communication and coordination work. I do see your use case but the query plugin provides an extension point to set your own Stargate query handler and use that with your community. Our default is RejectStargateQuerier currently.

The AcceptListStargateQuerier function accepts any codec.Codec implementation. Why not use this to wrap your logic with a custom MarshalJSON implementation that makes use of your WasmAnyResolver. Simple, testable and no need to fork.
WDYT?

[dadamu]

@alpe I think it the best solution for my usecase. Thanks for the wonderful solution!