Get Ledger Balance for Principal ID

Developers
1

So I usually get the ledger balance for a user using the backend but I want to use the frontend libraries available for me since they have a lot more features.

When getting a user’s account balance in motoko, I’d do this:


    public func getAccountBalance(principalId : Principal) : async Nat {
      let balance = await ledger.icrc1_balance_of({owner = principalId; subaccount = null});
      return balance;
    };

Giving me their account balance. I get an error when I try to replicate this on the frontend using the IcrcLedgerCanister type from the @dfinity/ledger-icrc library:

image
image1112×468 107 KB

Specifically:

Canister called ic0.trap with message: failed to decode call arguments: Custom(Fail to decode argument 0 from table2 to record { owner : principal; subaccount : opt blob }\n\nCaused by:\n Deserialize error: invalid length 0, expected an array of length 32)

Now again on the backend I have a function that pads the 29 byte array to make it 32 bytes, just wondering if there is an example anywhere of how to do this on the frontend?

2

Not exactly sure what you are looking for nor if its relates but, you can maybe have a look to the neuronSubaccount or AccountIdentifier implementation.

3

You can read my implement here
or use this lib the same source above but as a package :smiley:

4

Someone deposited FPL to their OpenFPL principal ID, which is fine, it’s where the winnings will go too.

I want to show the balance, usually I do this by getting from the backend and sending a DTO to the frontend. But I’d like to try just getting the balance directly in the frontend to save the round trip.

5

Your original question is about left padding, so I answered your original question. :man_shrugging:

If it’s another question, please share a code snippet and some details about the values, not sure what’s your issue.

6

My original question and the second comment are both about getting the FPL balance using some kind of frontend library. It’s fine I’ll just use the backend.

7

Ok, as you wish. Feel free to provide a snippet in which you get the issue and some data. Happy to have a look.

8 

async function getFPLBalance(): Promise<bigint> {
let identity: OptionIdentity;

authStore.subscribe(async (auth) => {
identity = auth.identity;
});

if (!identity) {
return 0n;
}

let principalId = identity.getPrincipal();

console.log(principalId);

const agent = await createAgent({
identity: identity,
host: import.meta.env.VITE_AUTH_PROVIDER_URL,
fetchRootKey: process.env.DFX_NETWORK === "local",
});

console.log(principalId);
const { balance } = IcrcLedgerCanister.create({
agent,
canisterId:
process.env.DFX_NETWORK === "ic"
? Principal.fromText("ddsp7-7iaaa-aaaaq-aacqq-cai")
: Principal.fromText("avqkn-guaaa-aaaaa-qaaea-cai"),
});

if (principalId) {
try {
let result = await balance({
owner: principalId,
subaccount: [],
certified: false,
});
console.log(result)
return result;
} catch (err: any) {
console.error(err);
}
}

return 0n;
} ``` this was what was giving me the error
9

Thanks for the snippet.

Not sure exactly if your extracted few parts or if it’s one to one your implementation. If the latest, their might be a race condition regarding the identity, therefore, I would add a console.log(principalId.toText() just before the call to balance and do a manual test to observe if indeed the owner is correctly set.

As a second try, I would try to not provide the subaccount if it is not used.

console.log('Is there a race condition?', principalId.toText());

let result = await balance({
   owner: principalId,
   certified: false,
});
2 Likes
10

Hi David,

You were spot on, the way to get it working was to remove the subaccount: and just have the owner propery in the params.

Thanks for the help.
James

1 Like