Send an ERC-20 token

In this tutorial we'll use Rust and the ethers-rs library to send an ERC-20 token from one address to another. This tutorial uses the Sepolia testnet and sends the Chainlink token (LINK).

Prerequisites

• Make sure that you have test LINK in your MetaMask wallet. You can obtain test LINK for the Sepolia network using the Chainlink faucet. Make sure that the Ethereum Sepolia network is selected on the top right of the faucet page when you connect your MetaMask wallet.
• Install Rust from The Cargo Book.

Send the token

1. Create a new project

Open a terminal and create a new project.

cargo new infura_rs

This creates the infura_rs directory with the following structure:

infura_rs
├── Cargo.toml
└── src
    └── main.rs

info

Refer to the Cargo documentation for more information about getting started with Cargo.

2. Edit the dependencies

Open Cargo.toml with your preferred editor and add the following dependencies to it:

[dependencies]
ethers = "2.0"
eyre = "0.6.8"
hex = "0.4.3"
tokio = { version = "1.28.2", features = ["full"] }
serde_json = "1.0.96"

3. Copy the contract ABI

• Create a text file with the name ct.json in the infura-rs project directory. Visit the ChainLink Token site on Etherscan and copy the Contract ABI (you will see it in a bottom section of the page) into the ct.json file.

4. Update the main code

Open the Rust source src/main.rs and replace its contents with the following code:

use ethers::{
  middleware::SignerMiddleware,
  providers::{Http, Middleware, Provider},
  signers::{LocalWallet, Signer},
  types::{Address, U256},
  contract::abigen
};
use eyre::Result;
use std::convert::TryFrom;
use std::sync::Arc;
use serde_json::Value;

#[tokio::main]
async fn main() -> Result<()> {
  // connect to the network, don't forget to replace your INFURA_API_KEY
  let provider = Provider::<Http>::try_from("https://sepolia.infura.io/v3/INFURA_API_KEY")?;

  let chain_id = provider.get_chainid().await?;

  let contract_address = "0x779877A7B0D9E8603169DdbD7836e478b4624789".parse::<Address>()?;

  // define a `ERC20Contract` struct from the ABI
  abigen!(ERC20Contract, "./ct.json",);

  let to_address = "0xF1B792820b52e6503208CAb98ec0B7b89ac64D6A".parse::<Address>()?;

  // Create the contract instance to let us call methods of the contract and let it sign transactions with the sender wallet.
  // for simplicity replace the private key (without 0x), ofc it always recommended to load it from an .env file or external vault
  let wallet: LocalWallet = "SIGNER_PRIVATE_KEY"
    .parse::<LocalWallet>()?
    .with_chain_id(chain_id.as_u64());

  let signer = Arc::new(SignerMiddleware::new(provider, wallet.with_chain_id(chain_id.as_u64())));
  let contract = ERC20Contract::new(contract_address, signer);

  // Fetch the decimals used by the contract so we can compute the decimal amount to send.
  let whole_amount: u64 = 1;
  let decimals = contract.decimals().call().await?;
  let decimal_amount = U256::from(whole_amount) * U256::exp10(decimals as usize);

  // Transfer the desired amount of tokens to the `to_address`
  let tx = contract.transfer(to_address, decimal_amount);
  let pending_tx = tx.send().await?;
  let _mined_tx = pending_tx.await?;

  println!("Transaction Receipt: {}", serde_json::to_string(&_mined_tx)?);

  // Extract the tx hash for printing
  let json_str = serde_json::to_string(&_mined_tx)?;
  let json: Value = serde_json::from_str(&json_str)?;

  if let Some(transaction_hash) = json["transactionHash"].as_str() {
    println!("\n URL: https://sepolia.etherscan.io/tx/{}", transaction_hash);
  } else {
    println!("Transaction Hash not found");
  }

  Ok(())
}

Next, make the following updates to the above code:

• On line 17 replace the INFURA_API_KEY with the API key of your API project from the Infura dashboard.
• On line 30 replace the SIGNER_PRIVATE_KEY with the private key of your Ethereum account.

Secure your keys

To better secure your keys, follow the recommended approach described in the section Create the .env file.

4. Run the code

From the infura_rs directory, run the code.

cargo run

You will see an output similar to the following.

Use the wrap button

Use the wrap button on the top right of the below code block window for wrapped display.

Finished dev [unoptimized + debuginfo] target(s) in 0.31s
     Running `target/debug/infura_rs`
Transaction Receipt: {"transactionHash":"0x301ae601943c5a1822886bf36e58c289ef942ca4bb08226ea3090b685aef9c7e","transactionIndex":"0x4","blockHash":"0xba6c880b14a7927ed2b6a5ac4e434d13d051dc770fe5f68666bb4d9b9ee1faed","blockNumber":"0x3a91b7","from":"0xe33fef60722ba79989aeaa1b6e6daf7f351c0fbb","to":"0x779877a7b0d9e8603169ddbd7836e478b4624789","cumulativeGasUsed":"0xd4673","gasUsed":"0x86fe","contractAddress":null,"logs":[{"address":"0x779877a7b0d9e8603169ddbd7836e478b4624789","topics":["0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef","0x000000000000000000000000e33fef60722ba79989aeaa1b6e6daf7f351c0fbb","0x000000000000000000000000f1b792820b52e6503208cab98ec0b7b89ac64d6a"],"data":"0x0000000000000000000000000000000000000000000000000de0b6b3a7640000","blockHash":"0xba6c880b14a7927ed2b6a5ac4e434d13d051dc770fe5f68666bb4d9b9ee1faed","blockNumber":"0x3a91b7","transactionHash":"0x301ae601943c5a1822886bf36e58c289ef942ca4bb08226ea3090b685aef9c7e","transactionIndex":"0x4","logIndex":"0x7","removed":false}],"status":"0x1","logsBloom":"0x00000004000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000008000002000000000000000000000000000000000000000000000000000000000000000000000000000000000000000010000000000000000000000040000001000000800000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000082000000000000000000000000000000008000000100000000000000000000000000008000000000000000000000000000000000000000000000000000","type":"0x2","effectiveGasPrice":"0xb2d05e09"}

 URL: https://sepolia.etherscan.io/tx/0x301ae601943c5a1822886bf36e58c289ef942ca4bb08226ea3090b685aef9c7e

Visit the URL displayed at the bottom of the above terminal log to confirm the transfer of the LINK token.