Fetch Signers - Frontend (Wallet Integration)

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Related API: Fetch signers

Important Note

The Neynar Client Instantiation and API calls (fetchNonce and fetchSigners) should ideally be performed on the backend to protect your API key and maintain security.

Prerequisites

1. Ethereum-Enabled Browser
   Ensure you are using a browser with a wallet like MetaMask installed.

2. API Key
   Obtain an API key from dev portal

3. Dependencies Installed

   Install the required packages:

   shell

   yarn add siwe viem @neynar/nodejs-sdk
   

Code Breakdown and Steps

1. Import Required Libraries
   The code starts by importing the necessary libraries:

   javascript

   import { SiweMessage } from "siwe";
   import { createWalletClient, custom, publicActions } from "viem";
   import { optimism } from "viem/chains";
   import { NeynarAPIClient, Configuration } from "@neynar/nodejs-sdk";
   

2. Configure Neynar API Client
   Set up the Neynar API client with your API key and base path. Note that this should ideally be done on the backend for security reasons:

   JavaScript

   const config = new Configuration({
    apiKey: "YOUR_API_KEY_HERE",
   });
   
   const client = new NeynarAPIClient(config);
   

3. Create the Wallet Client
   The createWalletClient function initializes a wallet client using the viem library. It uses window.ethereum to connect to the browser's wallet:

   JavaScript

   const wallet = createWalletClient({
    chain: optimism,
    transport: custom(window.ethereum),
   }).extend(publicActions);
   

4. Create the SIWE Message
   The createSiweMessage function generates a SIWE message with details such as domain, address, and nonce:

   JavaScript

   async function createSiweMessage(address, statement) {
     const { nonce } = await client.fetchNonce();
   
     const message = new SiweMessage({
    scheme: "http",
    domain: "localhost:8080",
    address,
    statement,
    uri: "http://localhost:8080",
    version: "1",
    chainId: "1",
    nonce: nonce,
    });
   
     return message.prepareMessage();
   }
   

5. Sign and Verify the Message
   The fetchSigners function retrieves the user's Ethereum address, generates a SIWE message, signs it, and verifies the signature using the Neynar API.

   Note:

   1. Neynar API should ideally be accessed from the backend
   2. The address should be the custody_address of the farcaster account (Check custody_address here)
      
      
   JavaScript

   async function fetchSigners() {
     const address = (await wallet.getAddresses())[0];
   
     let message = await createSiweMessage(
    address,
       "Sign in with Ethereum to the app."
    );
   
     const signature = await wallet.signMessage({ account: address, message });
   
     const { signers } = await client.fetchSigners({ message, signature });
   
     return signers;
   }
   

6. Execute the Function
   Call the fetchSigners function and handle the response or errors:

   JavaScript

   fetchSigners()
    .then((signers) => {
    console.log("\n\nsigners:", signers, "\n\n");
    })
    .catch((error) => {
    console.error("error:", error);
    });
   

Expected Output

[
  {
    "object": "signer",
    "signer_uuid": "19d0c5fd-9b33-4a48-a0e2-bc7b0555baec",
    "public_key": "0xe4abc135d40f8a6ee216d1a6f2f4e82476dff75f71ea53c5bdebca43f5c415b7",
    "status": "approved",
    "fid": 0
  },
  {
    "object": "signer",
    "signer_uuid": "08c71152-c552-42e7-b094-f510ff44e9cb",
    "public_key": "0xe4cd577123def73295dd9991c589b59b48cdc976b5e83a9ad8d2a13fcfcc0e72",
    "status": "approved",
    "fid": 0
  }
]

For additional help, feel free to contact us.