Substrate Utilities - SCALE Decoder

[lucgerrits]

Hi,
The SCALE Decoder looks useful but I can't make it work. I'm trying to decode Substrate metadata (V12).
I get a long array of numbers, I'm not sure what to think about it.
I don't know exactly what to put in the custom types.

Do you have any suggestions?

-Luc

[shawntabrizi]

SCALE Decoder does not automatically know what you want to decode. You must provide it the types and structures you need.

The metadata type is very complex, and there are easier ways to retrieve it using Polkadot JS:

const data = await api.rpc.state.getMetadata()

What is it you are trying to do specifically?

[lucgerrits]

I see. Well, my goal is to decode metadata for polkadot_api_cpp . The issue usetech-llc/polkadot_api_cpp#32 resume my situation.

In short: polkadot_api_cpp has metadata maintained up to V6 (see here), and I'm trying to use the polkadot_api_cpp for metadata V12. I need to be in C++ because my goal is to implement it on a small (or even very small) IoT.

Your tool could maybe help me to understand better the metadata structure to code the V12 in polkadot_api_cpp. But it doesn't seem easy!!

[shawntabrizi]

Yeah I dont think my utility will help you here, but check out:

https://github.com/polkadot-js/api/tree/master/packages/metadata/src

and

https://github.com/paritytech/substrate/blob/master/frame/metadata/src/lib.rs#L392