Mint Collectibles Using a Gasless Serverless Transactions API

pnpm install wrangler --save-dev
alias wrangler='./node_modules/.bin/wrangler'

wrangler login

wrangler init

import { Session } from "@0xsequence/auth";
import { ethers } from "ethers";
 
(async () => {
  // Generate a new EOA
  // const wallet = ethers.Wallet.createRandom()
  // const privateKey = wallet.privateKey
 
  // Or, use an existing EOA private key
  const privateKey = "";
 
  // Open a Sequence session, this will find or create
  // a Sequence wallet controlled by your server EOA
  const session = await Session.singleSigner({
    signer: privateKey,
    projectAccessKey: "access_key",
  });
 
  const signer = session.account.getSigner(1);
  console.log(`Your transactions API wallet address: ${signer.account.address}`);
})();

pnpm install 0xsequence @0xsequence/network

import { sequence } from "0xsequence";
import { networks, findSupportedNetwork } from "@0xsequence/network";
 
export interface Env {
  PKEY: string; // Private key for EOA wallet
  CONTRACT_ADDRESS: string; // Deployed ERC1155 or ERC721 contract address
  PROJECT_ACCESS_KEY: string; // From sequence.build
  CHAIN_HANDLE: string; // Standardized chain name – See https://docs.sequence.xyz/multi-chain-support
}
 
// use the sequence api to verify proof came from a sequence wallet
const verify = async (
  chainId: string,
  walletAddress: string,
  ethAuthProofString: string
): Promise<Boolean> => {
  const api = new sequence.api.SequenceAPIClient("https://api.sequence.app");
  const { isValid } = await api.isValidETHAuthProof({
    chainId,
    walletAddress,
    ethAuthProofString,
  });
  return isValid;
};
 
async function handleRequest(
  request: Request,
  env: Env,
  ctx: ExecutionContext
): Promise<Response> {
 
  if (request.method === "OPTIONS") {
		return new Response(null, {
			headers: {
				// Allow requests from any origin - adjust this as necessary
				"Access-Control-Allow-Origin": "*",
				
				// Allows the headers Content-Type, your-custom-header
				"Access-Control-Allow-Headers": "Content-Type, your-custom-header",
				
				// Allow POST method - add any other methods you need to support
				"Access-Control-Allow-Methods": "POST",
				
				// Optional: allow credentials
				"Access-Control-Allow-Credentials": "true",
				
				// Preflight cache period
				"Access-Control-Max-Age": "86400", // 24 hours
			}
		});
	}
 
  if (env.PKEY === undefined || env.PKEY === "") {
    return new Response("Make sure PKEY is configured in your environment", {
      status: 400,
    });
  }
 
  if (env.CONTRACT_ADDRESS === undefined || env.CONTRACT_ADDRESS === "") {
    return new Response(
      "Make sure CONTRACT_ADDRESS is configured in your environment",
      { status: 400 }
    );
  }
 
  if (env.PROJECT_ACCESS_KEY === undefined || env.PROJECT_ACCESS_KEY === "") {
    return new Response(
      "Make sure PROJECT_ACCESS_KEY is configured in your environment",
      { status: 400 }
    );
  }
 
  if (env.CHAIN_HANDLE === undefined || env.CHAIN_HANDLE === "") {
    return new Response(
      "Make sure CHAIN_HANDLE is configured in your environment",
      { status: 400 }
    );
  }
 
  const chainConfig = findSupportedNetwork(env.CHAIN_HANDLE);
 
  if (chainConfig === undefined) {
    return new Response("Unsupported network or unknown CHAIN_HANDLE", {
      status: 400,
    });
  }
 
  // POST request
  if (request.method === "POST") {
    // parse the request body as JSON
    const body = await request.json();
    const { proof, address, tokenId }: any = body;
    try {
      // check that the proof is valid
      if (await verify(env.CHAIN_HANDLE, address, proof)) {
        try {
          // mocked call
          const res = await callContract(request, env, address, tokenId);
          return new Response(`${res.hash}`, { status: 200 });
        } catch (err: any) {
          console.log(err);
          return new Response(`Something went wrong: ${JSON.stringify(err)}`, {
            status: 400,
          });
        }
      } else {
        return new Response(`Unauthorized`, { status: 401 });
      }
    } catch (err: any) {
      return new Response(`Unauthorized ${JSON.stringify(err)}`, {
        status: 401,
      });
    }
  }
  // GET request
  else {
    try {
      // mocked call
      const res = await getBlockNumber(env.CHAIN_HANDLE, request);
      return new Response(`Block Number: ${res}`);
    } catch (err: any) {
      return new Response(`Something went wrong: ${JSON.stringify(err)}`, {
        status: 500,
      });
    }
  }
}
 
const getBlockNumber = async (
  chainId: string,
  request: Request
): Promise<number> => {
  return chainId;
};
 
const callContract = async (
  request: Request,
  env: Env,
  address: string,
  tokenId: number
): Promise<ethers.providers.TransactionResponse> => {
  return { hash: "0x" } as any;
};
 
export default {
  async fetch(request: Request, env: Env, ctx: ExecutionContext) {
    // Process the request and create a response
    const response = await handleRequest(request, env, ctx);
 
    // Set CORS headers
    response.headers.set("Access-Control-Allow-Origin", "*");
    response.headers.set(
      "Access-Control-Allow-Methods",
      "GET, POST, PUT, DELETE, OPTIONS"
    );
    response.headers.set("Access-Control-Allow-Headers", "Content-Type");
 
    // return response
    return response;
  },
};

[vars]
PKEY = "" # Private key for EOA wallet
CONTRACT_ADDRESS = "" # // Deployed ERC1155 or ERC721 contract address
PROJECT_ACCESS_KEY = "" # From sequence.build
CHAIN_HANDLE = "" # // Standardized chain name – See https://docs.sequence.xyz/multi-chain-support

...
node_compat = true # add this line
...

curl -X POST https://your-worker.your-subdomain.workers.dev \
-H "Content-Type: application/json" \
-d '{"proof": "<some_proof>", "address": "<some_address>", "tokenId": 0 }'
 
... invalid proof string ...
 
# and if you replace with actual proof (from a wallet client login) and address on polygon, it should return
success

curl -X POST https://your-worker.your-subdomain.workers.dev \
-H "Content-Type: application/json" \
-d '{"proof": "<some_proof>", "address": "<some_address>", "tokenId": 0 }'

pnpm install @0xsequence/auth ethers

import { ethers } from 'ethers'
import { Session, SessionSettings } from '@0xsequence/auth'
 
...
 
const getBlockNumber = async (chainId: string, request: Request): Promise<number> => {
	const nodeUrl = `https://nodes.sequence.app/${chainId}`
	const provider = new ethers.providers.JsonRpcProvider({ url: nodeUrl, skipFetchSetup: true })
	return await provider.getBlockNumber()
}
 
const callContract = async (request: Request, env: Env, address: string, tokenId: number): Promise<ethers.providers.TransactionResponse> => {
 
	const nodeUrl = `https://nodes.sequence.app/${env.CHAIN_HANDLE}`
	const relayerUrl = `https://{env.CHAIN_HANDLE}-relayer.sequence.app`
	const contractAddress = env.CONTRACT_ADDRESS
 
 
	// instantiate settings
	const settings: Partial<SessionSettings> = {
		networks: [{
			...networks[findSupportedNetwork(env.CHAIN_HANDLE)!.chainId],
			rpcUrl: findSupportedNetwork(env.CHAIN_HANDLE)!.rpcUrl,
			relayer: {
				url: relayerUrl,
				provider: {
					url: findSupportedNetwork(env.CHAIN_HANDLE)!.rpcUrl
				}
			}
		}],
	}
 
    // create a single signer sequence wallet session
	const session = await Session.singleSigner({
		settings: settings,
		signer: env.PKEY,
		projectAccessKey: env.PROJECT_ACCESS_KEY
	})
 
	// get signer
	const signer = session.account.getSigner(findSupportedNetwork(env.CHAIN_HANDLE)!.chainId)
 
	// create interface from partial abi
	const collectibleInterface = new ethers.Interface([
		'function mint(address to, uint256 tokenId, uint256 amount, bytes data)'
	])
 
	// create calldata
	const data = collectibleInterface.encodeFunctionData(
		'mint', [address, tokenId, 1, "0x00"]
	)
 
	// create transaction object
	const txn = { to: contractAddress, data }
 
	try {
		return await signer.sendTransaction(txn)
	} catch (err) {
		throw err
	}
}