Example Usage

The Sei precompiles can be used like any standard smart contract on the EVM. For example, using ethers.js , you can query and execute actions on a CosmWasm contract as follows:

Setup

To install ethers, run the following command in your project directory terminal:


npm install ethers
npm install @sei-js/evm

Next, you’ll need to use one of the precompiles in EVM Precompiles section. In this example, we’re going to be using the CosmWasm precompile:


// Import Wasm precompile address and ABI
// View the entire ABI here: https://github.com/sei-protocol/sei-chain/tree/evm/precompiles/wasmd
import { WASM_PRECOMPILE_ABI, WASM_PRECOMPILE_ADDRESS } from '@sei-js/evm';

Using the contract

Next, we’ll set up a provider and contract to interact with the blockchain:


import { ethers, toUtf8Bytes, toUtf8String } from 'ethers';
 
// Using MetaMask as the signer and provider
const provider = new ethers.BrowserProvider(window.ethereum);
const signer = await provider.getSigner();
 
// Create a contract with the signer
const contract = new ethers.Contract(WASM_PRECOMPILE_ADDRESS, WASM_PRECOMPILE_ABI, signer);

If using MetaMask, the wallet must be switched to the Sei EVM Devnet chain. Information to import the Sei EVM Devnet chain can be found here.

Querying & Executing a CosmWasm Contract

Once you have the contract, you can query and execute messages to any CosmWasm smart contract.


// Counter CosmWasm contract (used for testing on arctic-1)
// Replace with your contract as needed
const COUNTER_CONTRACT_ADDRESS = 'sei1eyfccmjm6732k7wp4p6gdjwhxjwsvje44j0hfx8nkgrm8fs7vqfsy2jxff';
 
// Query to get the count on the counter contract
const queryMsg = { get_count: {} };
const queryResponse = await contract.query(COUNTER_CONTRACT_ADDRESS, toUtf8Bytes(JSON.stringify(queryMsg)));
console.log(toUtf8String(queryResponse));
 
// Execute message to increment the count on the contract.
// No funds are attached since the increment method does not require sei.
const executeMsg = { increment: {} };
const executeResponse = await contract.execute(
  COUNTER_CONTRACT_ADDRESS,
  toUtf8Bytes(JSON.stringify(executeMsg)),
  toUtf8Bytes(JSON.stringify([])) // Used for sending funds if needed
);
 
// Wait for the transaction to be confirmed
await executeResponse.wait();
console.log(executeResponse);

Executing a payable function

In this example, we execute the ‘donate’ method on our contract. This is similar to the increment method, but also receives funds from the user and stores it in the contract.


// Execute a message to donate to the contract.
const executeMsg = { donate: {} };
 
// Funds are attached via overrides. This example is specific to ethers.js
const overrides = {
  value: ethers.parseEther('3.2') // Sending 3.2 sei
};
const executeResponse = await contract.execute(
  COUNTER_CONTRACT_ADDRESS,
  toUtf8Bytes(JSON.stringify(executeJSON)),
  toUtf8Bytes(JSON.stringify({ denom: 'usdc', amount: '100' })), // Also send 100 usdc
  overrides
);
 
await executeResponse.wait();
const receipt = await provider.getTransactionReceipt(executionResponse.hash);

For payable contracts, Sei amounts have to be sent directly to the contract while other denoms should use the coins field.