Attaining an Integer from StorageKey

Question

I'm porting a script from TypeScript using the Polkadot.JS/api to Rust using Subxt.

    let query = polkadot::storage().referenda().referendum_info_for_root();

    let mut results = api.storage().at_latest().await?.iter(query,10).await?;

    while let Some((key, value)) = results.next().await? {

With reference to the above, I'm having trouble getting the referendum id from the key. Within my TypeScript code I would use something like key.toHuman()[0].

Regards,

Answer 1

I got some help from @Turboflakes the developer behind CrunchBot. He referred me to an article and supported with some code to help 'decode' the Storage key.

https://www.shawntabrizi.com/substrate/transparent-keys-in-substrate/

Within the while loop I use:

get_ref_id_from_storage_key(key.0.to_vec())

The function's details are:

pub fn get_ref_id_from_storage_key(key: Vec<u8>) -> u32 {
    let s = &key[key.len() - 4..];
    let v: [u8; 4] = s.try_into().expect("slice with incorrect length");
    u32::from_le_bytes(v)
}