How to use Defender Relayer Provider properly to pay for someone elses transaction?

Support Defender
1

My understanding of Defender was, that I could use them to let someone else pay for a transaction that was signed with another account.

Lets say:

0xAccountA sends ERC1155-tokens to 0xAccountB, but 0xAccountC is paying for that.

In order to achieve this, I did the following:

Given is apiKey and secretKey as response from

const key = await relayClient.createKey(relayerId);

Then I did:

    const credentials = { apiKey: apiKey, apiSecret: secretKey };

    const provider = new DefenderRelayProvider(credentials);
    const signer = new DefenderRelaySigner(credentials, provider, { speed: 'fast' });

    console.log("Signer", await signer.getAddress())
    const contract = new ethers.Contract(contractAddress, abi, signer);

    tx = await contract.functions.safeTransferFrom(from, to, tokenId, amount, nullBytes);

I think, the misconception of my thoughts is, that the Signer must be the From-address, because from owns the tokens. But sending the transaction must be done with the Relayer-Account, which shall pay for that.

How can I achieve that from is signing the transaction but the Relayer-Account is paying for it?

:computer: Environment

"defender-relay-client": "^1.30.0",
"ethers": "^5.6.0",

:memo:Details

see above

:1234: Code to reproduce

see above

2

You can follow the steps in this guide to set up a gasless meta-transaction. There are a few additional components that are needed to make all this happen.

3

According to this guide, it looks like Relayer is only working with SmartContracts that support ERC2771 in conjunction with MinimalForwarder.
Does this mean for "normal" ERC1155-contracts which do not support ERC2771 this won't work?

4

If you're looking to replicate the meta-transaction functionality in the guide, those components are necessary.

5

Thank's a lot for explanation. Is there any other way to pay for a transaction of someone else on conventional contracts without ERC2771-support?