IChainPayReceiver.sol

The IChainPayReceiver interface enables your smart contract to receive payments from the ChainPay contract.

interface IChainPayReceiver {
    function paid(address from, bytes memory data) external;
}

paid()

The paid function is called by the ChainPay smart contract once a payment has been successfully processed.

Parameters

Name	Type	Description
from	address	The address of the sender who made the payment
data	bytes	The data passed along when creating the ChainPay transaction. This is why the data_raw option exists in the CreateTransactionInput, which accepts a Uint8Array. This allows for extra parameters or data to be included for your callback.

Example Implementation

Below is an example of an ERC20 token contract that allows users to mint tokens through a ChainPay payment.

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import "./IChainPayReceiver.sol";
import "./IChainPay.sol";

contract MyToken is ERC20, IChainPayReceiver {
    address private immutable chainPay;

    constructor(string memory name, string memory symbol, address _chainPay) ERC20(name, symbol) {
        // Register the contract with ChainPay and set the signer
        IChainPay(_chainPay).contractToggle();
        IChainPay(_chainPay).setSigner(msg.sender);

        chainPay = _chainPay;
    }

    function paid(address from, bytes memory data) public override {
        require(msg.sender == chainPay, "Unauthorized sender");
        _mint(from, 10 ** decimals()); // Mint 10 tokens to the payer
    }
}