Substrate: Unable to instantiate multiple balances

[gregdhill]

I'm trying to configure my runtime to operate with two currencies by instantiating the balances pallet twice (as described here). To configure my test environment the genesis is built as follows:

            let mut storage = system::GenesisConfig::default()
                .build_storage::<Runtime>()
                .unwrap();

            balances::GenesisConfig::<Runtime, balances::Instance1> {
                balances: vec![
                    (AccountId::from(ALICE), 1_000_000),
                    (AccountId::from(BOB), 1_000_000),
                ],
            }
            .assimilate_storage(&mut storage)
            .unwrap();

            balances::GenesisConfig::<Runtime, balances::Instance2> {
                balances: vec![
                    (AccountId::from(ALICE), 500_000),
                    (AccountId::from(BOB), 500_000),
                ],
            }
            .assimilate_storage(&mut storage)
            .unwrap();

However, if I then call free_balance on each module they will both return 500_000 despite the fact that the former instantiation gives both accounts 1_000_000 in this case. Furthermore, deposit_into_existing updates the balance of the account for each currency.

[gregdhill]

Example runtime:

impl balances::Trait<balances::Instance1> for Runtime {
    type Balance = Balance;
    type Event = Event;
    type DustRemoval = ();
    type ExistentialDeposit = ExistentialDeposit;
    type AccountStore = System;
}

impl balances::Trait<balances::Instance2> for Runtime {
    type Balance = Balance;
    type Event = Event;
    type DustRemoval = ();
    type ExistentialDeposit = ExistentialDeposit;
    type AccountStore = System;
}

```rust
construct_runtime!(
pub enum Runtime where
Block = Block,
NodeBlock = opaque::Block,
UncheckedExtrinsic = UncheckedExtrinsic
{
...
Currency1: balances::::{Module, Call, Storage, Config, Event},
Currency2: balances::::{Module, Call, Storage, Config, Event},
....
}
);

[AurevoirXavier]

Because there's only one currency in AccountData.

Try our solution:

https://github.com/darwinia-network/darwinia-common/blob/master/frame/support/src/macros.rs#L3.

https://github.com/darwinia-network/darwinia-common/blob/master/bin/node-template/runtime/src/lib.rs#L28

https://github.com/darwinia-network/darwinia-common/blob/master/bin/node-template/runtime/src/lib.rs#L515

[kianenigma]

Explanation from @AurevoirXavier seem to make sense to me; You need to change the AccountStore of the two to something else.

You could easily hack a module together to just store your account balances in the meantime.

Also, substrate should provide something like generic-acocunt-store that you can use if you don't want to use the system as account store. This can be a good first issue for someone working on the runtime. Basically look at how system::Module<T> is implementing StoredMap and replicate that in an isolated way in a new module. The new module will not have Call or anything else, only provides storage.

[xlc]

It is already possible to store the data in balances directly. This can be closed.

https://github.com/paritytech/substrate/blob/db8916a48e2bfc9ae9c18c3fa617f7302432c685/frame/balances/src/tests_local.rs#L110-L114

[shawntabrizi]

Yes, everything mentioned in this thread is correct, and I think the right solution is that @xlc mentioned here.

Simply update your pallet configuration to store your balances account in the pallet rather than in the System account.