How to hardcode few AccountIds to a storage in migration?

Question

During a storage migration I want to add few SS58 Address in one storage. How to hardcode it in migration script?

Answer 1

See this tutorial on Substrate for the basics about migrations Basic storage migration, in this tutorial there is an example where it modifies the storage of a pallet (Nicks pallet) to include both a first name and an optional last name. The script has to transform the values to the new storage.

Your case is easier because if I understand correctly you just want to add some accounts into an storage. To see how to hardcore the an address, see this SE previous question: How to hardcode an address in the substrate runtime?.

A simple version of your code will look something like:

fn on_runtime_upgrade() -> frame_support::weights::Weight {
            let onchain_version = Pallet::<T>::on_chain_storage_version();
            if onchain_version < your_version {
                let account_hardcoded = AccountId::from_ss58check("account_hardcoded").unwrap();
                <YourStorage<T>>::put(account_hardcoded);
                // Return the weight consumed by the migration.
                T::DbWeight::get().reads_writes(1, 1)
            } else {
                log::info!(target: LOG_TARGET, "MigrateToV1 should be removed");
                T::DbWeight::get().reads(1)
            }
        }