chain_getBlock extrinsics encoding

[pgherveou]

When I query the chain_getBlock extrinsics, subxt deserialize the extrinsics bytes with scale

subxt/subxt/src/rpc/types.rs

Lines 113 to 126 in 1ad9a20

	#[derive(Clone, Debug)]
	pub struct ChainBlockExtrinsic(pub Vec<u8>);
	impl<'a> ::serde::Deserialize<'a> for ChainBlockExtrinsic {
	fn deserialize<D>(de: D) -> Result<Self, D::Error>
	where
	D: ::serde::Deserializer<'a>,
	{
	let r = impl_serde::serialize::deserialize(de)?;
	let bytes = Decode::decode(&mut &r[..])
	.map_err(|e| ::serde::de::Error::custom(format!("Decode error: {e}")))?;
	Ok(ChainBlockExtrinsic(bytes))
	}
	}

As a result if I compare the result of substrate export-blocks command or if I make a raw query to the rpc, I get different values for these extrinsics. If the subxt client is just supposed to return the result of the API call it should not try to interpret the payload.

Instead we should probably use something like this

pub struct ChainBlockExtrinsic(#[serde(with = "impl_serde::serialize")] pub Vec<u8>);

[jsdw]

I think that's a fair comment; all that Decode::decode is doing is removing the Compact(length) bytes from the beginning anyway and allocating a new vec in the process. Probably we can handle this "down the line" easily enough, avoid an extra allocation and have a slgihtly "purer" RPC call.