RPC return type `Balance` is not always decoded

[cmichi]

If ink!'s erc20 example is deployed with an initialSupply of 9999 the RPC method total_supply() does not decode the returned supply:

If 1000 is chosen for initialSupply the value is displayed as encoded. It also works for 9999 in polkadot-js:

Here's the contract: erc20.contract.zip.

The return type of total_supply is Balance. I suspect that there's an issue with decoding this type.

[awolokita]

I did a little debugging in Data.tsx::Data on this issue.

formatData for the Balance type yeilds a Type Codec. The if statement that catches this value is

if (type.info === _polkadot_types_types__WEBPACK_IMPORTED_MODULE_9__.TypeDefInfo.Plain) {
    return (0,_canvas_ui_react_util__WEBPACK_IMPORTED_MODULE_2__.truncate)((value === null || value === void 0 ? void 0 : value.toString()) || '()', TRUNCATE_TO); // TRUNCATE_TO === 16
}

When initialSupply = 1000, value === 1000000000000000 and typeof value === "number" and subsequently returns a nicely, non truncated base-10 number.

When initialSupply = 9999, value === "0x0000000000000000002386099b1bf000" and typeof value === "string" and subsequently returns a truncated copy of value.

Balance is defined in https://github.com/polkadot-js/api/blob/master/packages/types/src/interfaces/runtime/types.ts as extending u32 which eventually extends AbstractInt.

I think there are 2 questions to be answered here:

1. Why doesn't a "Balance" type yeild a Type instead of AbstractInt Codec?
2. Why is Data() invoked with value with two different types depending on its size?

[awolokita]

While digging around for #13 I found that codec.toHuman() gives us nice representations of lots of Codec types. In the case of Balance we get nice prefixed units.

For your case of a starting supply of 9999, codec.toHuman() yeilds "9.9990 kUnit". Instantiating with 1 Yotta gives us "1.0000 YUnit".

[achimcc]

@awolokita This seems to be an excellent solution, tried it and changed toJSON() to .toHuman() in the code. Thanks a lot for all your valuable contributions and sorry for not being responsive. canvas-ui is currently undergoing a re-write, please get in touch if would like to contribute to the new project at some point.

[awolokita]

@achimcc I'm glad the solution worked out well for you.

Looking forward to seeing the big refactor. I'd be happy to contribute more when the changes are up.