How to Sub-class Signer?

[tomarsachin2271]

I'm trying to build a SDK that wraps a Provider object eg. window.ethereum or ethers.providers.JsonRpcProvider

I'm overriding the send, sendAsync and request method of the provider object and instead of letting the wallet handle the transaction signing request, i'm handling the request and redirecting them to off-chain relayers, which then broadcast transaction to blockchain and return transaction hash, then SDK return the response object from send, sendAsync or request method accordingly.

I'm creating my SDK like this
let biconomy = new Biconomy(new ethers.providers.JsonRpcProvider(kovanRPCURL), { apiKey: <API_KEY>});

Then i create ethers instance,
let biconomyProvider = new ethers.providers.Web3Provider(biconomy);

Create the contract instatnce,
let contract = new ethers.Contract(contractAddress, contractABI, biconomyProvider);

Now the problem is the Contact doesn't have any signer information when i do

let tx = await contract.setQuote(newQuote);

I get this error

Error: sending a transaction requires a signer (operation="sendTransaction", code=UNSUPPORTED_OPERATION, version=contracts/5.0.11)

This is the workaround i found to let ethers know that there is a signer object associated, but its not actually required. I'm sure there is better way of doing this.

contract = new ethers.Contract(contractAddress, contractABI, biconomyProvider);

let connectedSigner = biconomyProvider.getSigner();
connectedSigner.getAddress = async () => {
    return userAddress;
}
contract = await contract.connect(connectedSigner);

I'm not able to connect the signer object from window.ethereum to my JsonRpcProvider object also for obvious reasons.

[ricmoo]

You probably want to sub-class Signer, not Provider.

The ethers library handles Signers and Providers as completely separate things; it sounds like you are coming from Web3.js.

If you sub-class Signer I think everything will just work for you. You only need to provide implementations for the 4 abstract methods and you should be good to go. You also probably want your Signer to take a provider in and expose it as the .provider property.

The VoidSigner is also a great starting point for a minimal Signer. Just drop in your implementation. :)

[TedMurphy]

My new.ethers.Contract works when I get the provider through Metamask but does not through JsonRpcProvider.

The website console error message using JsonRpcProvider is:

Unhandled Runtime Error
Error: unknown account #0 (operation="getAddress", code=UNSUPPORTED_OPERATION, version=providers/5.0.23)

Would you please take a look at this sequence and tell me the error?

This works for Web3Provider (Metamask) but not for JsonRpcProvider:

import { ethers } from "ethers";
let myProvider;
if (typeof window !== 'undefined' && typeof window.web3 !== 'undefined') {
// we are in the browser and metamask is running
myProvider = new ethers.providers.Web3Provider(window.ethereum);
} else {
// we are on the server OR the user is not running metamask
myProvider = new ethers.providers.JsonRpcProvider(
'https://rinkeby.infura.io/v3/800f33e8ff5344f8a36449905ffafa01'
);
}

The provider is used to instantiate a Contract:

const factory = new ethers.Contract(
contractAddress.CampaignFactory,
FactoryArtifact.abi,
myProvider.getSigner()
);

That Contract fails in the JsonRpcProvider case when a method is called:

const campaigns = await factory.getDeployedCampaigns();

Again, the website console error message is:

Unhandled Runtime Error
Error: unknown account #0 (operation="getAddress", code=UNSUPPORTED_OPERATION, version=providers/5.0.23)

[ricmoo]

INFURA does not provide accounts. You will need to pass a signer in if that is how you wish to sub-class it.

What are you trying to do with your sub-class that is different than the normal JsonRpcSigner?

[TedMurphy]

Thank you, that is very helpful. I guess I need to think of the signer and the provider as two separate things.