Batch ERC20 Transfer with Session Router

Let's execute a batch of user operations using session keys by leveraging the Batched Session Validation Module

Create new component

Let's Create a new component called BatchERC20Transfer.tsx and place it in the components folder.

The imports will be as follows:

import React from "react";
import { ethers } from "ethers";
import { BiconomySmartAccountV2, DEFAULT_SESSION_KEY_MANAGER_MODULE, DEFAULT_BATCHED_SESSION_ROUTER_MODULE, createSessionKeyManagerModule, createBatchedSessionRouterModule } from "@biconomy/account"
import usdcAbi from "@/utils/usdcAbi.json"
import { toast } from 'react-toastify';
import 'react-toastify/dist/ReactToastify.css';

interface props {
  smartAccount: BiconomySmartAccountV2;
  provider: ethers.providers.Provider;
  address: string;
}

Let's create the inital component:

const BatchERC20Transfer: React.FC<props> = ({ smartAccount, provider, address}) => {
  return(
    <button>Batch Transfer 1 USDC</button>
  )
}

export default BatchERC20Transfer;

This is going to be a basic button that simply transfers 1 USDC to two different recipients.

{
  isSessionActive && (
    <BatchERC20Transfer
      smartAccount={smartAccount}
      provider={provider}
      address={address}
    />
  );
}

Create transfer function

Let's create the function now to handle the transfer:

 const batchErc20Transfer = async () => {
    if (!address || !smartAccount || !address) {
      alert("Please connect wallet first");
      return;
    }
    try {
      toast.info('Transferring 1 USDC to two recipients...', {
        position: "top-right",
        autoClose: 15000,
        hideProgressBar: false,
        closeOnClick: true,
        pauseOnHover: true,
        draggable: true,
        progress: undefined,
        theme: "dark",
        });
      const erc20ModuleAddr = "0x000000D50C68705bd6897B2d17c7de32FB519fDA";
      const mockSessionModuleAddr = "0x7Ba4a7338D7A90dfA465cF975Cc6691812C3772E";
      // get session key from local storage
      const sessionKeyPrivKey = window.localStorage.getItem("sessionPKey");
      console.log("sessionKeyPrivKey", sessionKeyPrivKey);
      if (!sessionKeyPrivKey) {
        alert("Session key not found please create session");
        return;
      }
      const sessionSigner = new ethers.Wallet(sessionKeyPrivKey);
      console.log("sessionSigner", sessionSigner);

      // generate sessionModule
      const sessionModule = await createSessionKeyManagerModule({
        moduleAddress: DEFAULT_SESSION_KEY_MANAGER_MODULE,
        smartAccountAddress: address,
      });

      // genereate batched session router module
      const sessionRouterModule = await createBatchedSessionRouterModule({
        moduleAddress: DEFAULT_BATCHED_SESSION_ROUTER_MODULE,
        sessionKeyManagerModule: sessionModule,
        smartAccountAddress: address,
      });

      // set active module to session router module
      smartAccount = smartAccount.setActiveValidationModule(sessionRouterModule);

      const tokenContract = new ethers.Contract(
        // polygon mumbai usdc address
        "0xdA5289fCAAF71d52a80A254da614a192b693e977",
        usdcAbi,
        provider
      );
      let decimals = 18;

      try {
        decimals = await tokenContract.decimals();
      } catch (error) {
        throw new Error("invalid token address supplied");
      }

      const { data: data1 } = await tokenContract.populateTransaction.transfer(
        "0x322Af0da66D00be980C7aa006377FCaaEee3BDFD", // receiver address
        ethers.utils.parseUnits("1", decimals)
      );

      const { data: data2 } = await tokenContract.populateTransaction.transfer(
        "0xFA66E705cf2582cF56528386Bb9dFCA119767262", // receiver address
        ethers.utils.parseUnits("1", decimals)
      );

      // generate tx data to first erc20 transfer
      const tx1 = {
        to: "0xdA5289fCAAF71d52a80A254da614a192b693e977", //erc20 token address
        data: data1,
        value: "0",
      };

      // generate tx data to second erc20 transfer
      const tx2 = {
        to: "0xdA5289fCAAF71d52a80A254da614a192b693e977", //erc20 token address
        data: data2,
        value: "0",
      };

      // This will build the tx into a user op and send it.
      let userOpResponse = await smartAccount.sendTransaction([tx1, tx2], {
        params: {
          batchSessionParams: [
            {
              sessionSigner: sessionSigner,
              sessionValidationModule: erc20ModuleAddr,
            },
            {
              sessionSigner: sessionSigner,
              sessionValidationModule: mockSessionModuleAddr,
            },
          ],
        },
      });

      console.log("userOpHash", userOpResponse);
      const { receipt } = await userOpResponse.wait(1);
      console.log("txHash", receipt.transactionHash);
      const polygonScanlink = `https://mumbai.polygonscan.com/tx/${receipt.transactionHash}`
      toast.success(<a target="_blank" href={polygonScanlink}>Success Click to view transaction</a>, {
        position: "top-right",
        autoClose: 18000,
        hideProgressBar: false,
        closeOnClick: true,
        pauseOnHover: true,
        draggable: true,
        progress: undefined,
        theme: "dark",
        });
    } catch(err: any) {
      console.error(err);
    }
  }

Add this method to the onClick event of the button.

return(
    <button onClick={() => batchErc20Transfer}>Batch Transfer 1 USDC</button>
  )

Congrats! you have successfully integrated the batched session router module. Expand the code below to see the entire code:

Details

import React from "react";
import { ethers } from "ethers";
import { BiconomySmartAccountV2, DEFAULT_SESSION_KEY_MANAGER_MODULE, DEFAULT_BATCHED_SESSION_ROUTER_MODULE, createSessionKeyManagerModule, createBatchedSessionRouterModule } from "@biconomy/account"
import usdcAbi from "@/utils/usdcAbi.json"
import { toast } from 'react-toastify';
import 'react-toastify/dist/ReactToastify.css';

interface props {
  smartAccount: BiconomySmartAccountV2;
  provider: ethers.providers.Provider;
  address: string;
}


const BatchERC20Transfer: React.FC<props> = ({ smartAccount, provider, address}) => {

 const batchErc20Transfer = async () => {
  if (!address || !smartAccount || !address) {
    alert("Please connect wallet first");
    return;
  }
  try {
    toast.info('Transferring 1 USDC to two recipients...', {
      position: "top-right",
      autoClose: 15000,
      hideProgressBar: false,
      closeOnClick: true,
      pauseOnHover: true,
      draggable: true,
      progress: undefined,
      theme: "dark",
      });
    const erc20ModuleAddr = "0x000000D50C68705bd6897B2d17c7de32FB519fDA";
    const mockSessionModuleAddr = "0x7Ba4a7338D7A90dfA465cF975Cc6691812C3772E";
    // get session key from local storage
    const sessionKeyPrivKey = window.localStorage.getItem("sessionPKey");
    console.log("sessionKeyPrivKey", sessionKeyPrivKey);
    if (!sessionKeyPrivKey) {
      alert("Session key not found please create session");
      return;
    }
    const sessionSigner = new ethers.Wallet(sessionKeyPrivKey);
    console.log("sessionSigner", sessionSigner);

    // generate sessionModule
    const sessionModule = await createSessionKeyManagerModule({
      moduleAddress: DEFAULT_SESSION_KEY_MANAGER_MODULE,
      smartAccountAddress: address,
    });

    // genereate batched session router module
    const sessionRouterModule = await createBatchedSessionRouterModule({
      moduleAddress: DEFAULT_BATCHED_SESSION_ROUTER_MODULE,
      sessionKeyManagerModule: sessionModule,
      smartAccountAddress: address,
    });

    // set active module to session router module
    smartAccount = smartAccount.setActiveValidationModule(sessionRouterModule);

    const tokenContract = new ethers.Contract(
      // polygon mumbai usdc address
      "0xdA5289fCAAF71d52a80A254da614a192b693e977",
      usdcAbi,
      provider
    );
    let decimals = 18;

    try {
      decimals = await tokenContract.decimals();
    } catch (error) {
      throw new Error("invalid token address supplied");
    }

    const { data: data1 } = await tokenContract.populateTransaction.transfer(
      "0x322Af0da66D00be980C7aa006377FCaaEee3BDFD", // receiver address
      ethers.utils.parseUnits("1", decimals)
    );

    const { data: data2 } = await tokenContract.populateTransaction.transfer(
      "0xFA66E705cf2582cF56528386Bb9dFCA119767262", // receiver address
      ethers.utils.parseUnits("1", decimals)
    );

    // generate tx data to first erc20 transfer
    const tx1 = {
      to: "0xdA5289fCAAF71d52a80A254da614a192b693e977", //erc20 token address
      data: data1,
      value: "0",
    };

    // generate tx data to second erc20 transfer
    const tx2 = {
      to: "0xdA5289fCAAF71d52a80A254da614a192b693e977", //erc20 token address
      data: data2,
      value: "0",
    };

    // This will build the tx into a user op and send it.
    let userOpResponse = await smartAccount.sendTransaction([tx1, tx2], {
      params: {
        batchSessionParams: [
          {
            sessionSigner: sessionSigner,
            sessionValidationModule: erc20ModuleAddr,
          },
          {
            sessionSigner: sessionSigner,
            sessionValidationModule: mockSessionModuleAddr,
          },
        ],
      },
    });

    console.log("userOpHash", userOpResponse);
    const { receipt } = await userOpResponse.wait(1);
    console.log("txHash", receipt.transactionHash);
    const polygonScanlink = `https://mumbai.polygonscan.com/tx/${receipt.transactionHash}`
    toast.success(<a target="_blank" href={polygonScanlink}>Success Click to view transaction</a>, {
      position: "top-right",
      autoClose: 18000,
      hideProgressBar: false,
      closeOnClick: true,
      pauseOnHover: true,
      draggable: true,
      progress: undefined,
      theme: "dark",
      });
  } catch(err: any) {
    console.error(err);
  }
 }

  return(
    <button onClick={() => batchErc20Transfer}>Batch Transfer 1 USDC</button>
  )
}

export default BatchERC20Transfer;