Farcaster Frame Txn Example POST Handler

approve.js

    "txn": async function(req) {
      return new Promise(async function(resolve, reject) {
        var frame = {};
        frame.id = req.params.id;
        frame.square = true;
        frame.postUrl = `https://frm.lol/frames/${req.params.id}`;
        const frameResult = await util.validate(req); // neynar frame validation endpoint
        if (frameResult.valid == true) {
          if ("transactionId" in req.body.untrustedData) {
            // transaction has completed
            const txnId = req.body.untrustedData.transactionId;
            frame.imageText = "Your txId is " + txnId;
          } else {
            // return txn data
            // degen contract via ethers
            const provider = new ethers.providers.JsonRpcProvider(process.env.API_URL_BASE);
            const degen = new ethers.Contract(process.env.DEGEN_CONTRACT, degenJSON.abi, provider);
            const SPENDER_CONTRACT = "0xA238Dd80C259a72e81d7e4664a9801593F98d1c5"; // Aave Pool on Base (demo purposes)
            // calldata for an approve tx
            const calldata = degen.interface.encodeFunctionData("approve", [SPENDER_CONTRACT, ethers.utils.parseEther("69")]);
            const tx = {
              "chainId": "eip155:8453", // Base chainId
              "method": "eth_sendTransaction",
              "params": {
                "to": process.env.DEGEN_CONTRACT,
                "abi": degenJSON.abi,
                "data": calldata,
                "value": "0x0"
              }
            };
            return resolve(tx);
          } // if txnId
        } else {
          frame.imageText = "I'm sorry, I couldn't validate this frame.";
        }
        return resolve(frame);
      }); // return new Promise
    }, // txn