How to convert an associated type AccountId into a custom associated type AssetId in a Substrate pallet?

Question

I'm working on a Substrate pallet, and I have a custom associated type AssetId. I need to convert an AccountId into this AssetId. My Config trait looks like this:

#[pallet::config]
pub trait Config: frame_system::Config + TypeInfo + pallet_contracts::Config {
    /// Pallet ID.
    #[pallet::constant]
    type PalletId: Get<PalletId>;

    /// The overarching event type.
    type RuntimeEvent: From<Event<Self>> + IsType<<Self as frame_system::Config>::RuntimeEvent>;

    /// The currency trait.
    type Currency: Currency<Self::AccountId>;

    /// The balance type for assets (i.e. tokens).
    type AssetBalance: Balance
        + FixedPointOperand
        + MaxEncodedLen
        + MaybeSerializeDeserialize
        + TypeInfo;

    // Two-way conversion between asset and currency balances
    type AssetToCurrencyBalance: Convert<Self::AssetBalance, BalanceOf<Self>>;
    type CurrencyToAssetBalance: Convert<BalanceOf<Self>, Self::AssetBalance>;

    /// The asset ID type.
    type AssetId: MaybeSerializeDeserialize
        + MaxEncodedLen
        + TypeInfo
        + Clone
        + Debug
        + PartialEq
        + EncodeLike
        + Decode;

    /// The type for tradable assets.
    type Assets: Inspect<Self::AccountId, AssetId = Self::AssetId, Balance = Self::AssetBalance>
        + Transfer<Self::AccountId>;

    /// The type for liquidity tokens.
    type AssetRegistry: Inspect<Self::AccountId, AssetId = Self::AccountId, Balance = Self::AssetBalance>
        + Mutate<Self::AccountId>
        + Create<Self::AccountId>
        + Destroy<Self::AccountId>;

    /// Information on runtime weights.
    type WeightInfo: WeightInfo;

    /// Provider fee numerator.
    #[pallet::constant]
    type ProviderFeeNumerator: Get<BalanceOf<Self>>;

    /// Provider fee denominator.
    #[pallet::constant]
    type ProviderFeeDenominator: Get<BalanceOf<Self>>;

    /// Minimum currency deposit for a new exchange.
    #[pallet::constant]
    type MinDeposit: Get<BalanceOf<Self>>;
}

this is the function i need to convert <T as SysConfig>::AccountId to <T as pallet::Config>::AssetId .

#[pallet::call_index(0)]
        #[pallet::weight(<T as Config>::WeightInfo::create_exchange())]
        #[transactional]
        pub fn create_exchange(
            origin: OriginFor<T>,
            asset_id:  AssetIdOf<T>,
            liquidity_token_id:  AssetIdOf<T>,
            currency_amount: BalanceOf<T>,
            token_amount: BalanceOf<T>,
        ) -> DispatchResult {
            // -------------------------- Validation part --------------------------
            let caller = ensure_signed(origin)?;
    

            let exchange = Exchange {
                asset_id: asset_id.clone(),
                currency_reserve: <BalanceOf<T>>::zero(),
                token_reserve: <AssetBalanceOf<T>>::zero(),
                liquidity_token_id: liquidity_token_id.clone(),
            };

            
            Ok(())
        }

and this is my strct :

#[derive(Clone, Encode, Decode, Eq, PartialEq, RuntimeDebug, MaxEncodedLen, TypeInfo)]
    pub struct Exchange<T: Config> {
        pub asset_id: T::AccountId,
        pub currency_reserve: BalanceOf<T>,
        pub token_reserve: AssetBalanceOf<T>,
        pub liquidity_token_id: T::AccountId,
    }

i have to use T::AccountId for call contract for some actions :

let result = pallet_contracts::Pallet::<T>::bare_call(
            origin.clone(),
            contract_address.clone(),
            contracts_value,
            gas_limit,
            None,
            data,
            false,
            pallet_contracts::Determinism::Deterministic,
        );

and use AssetId for using T::AssetRegistry::mint_into .

T::AssetRegistry::mint_into(
            exchange.liquidity_token_id.clone(),
            &provider,
            liquidity_minted,
        )?;

when i need to rin this code it show me this error :

mismatched types expected associated type <T as pallet::Config>::AssetId found associated type <T as SysConfig>::AccountId

Repository

how can i sovle this problem ?

Answer 1

if I understand you right, you probably want to have some account id associated to a particular exchange from your example. You can create a system account for it, for example combining some prefix sacc/exch + asset_id.

System Accounts

Example