Truffle Migration: deploy or upgrade

Question

I would like to write the following logic in the migration script for my truffle project with upgradeable contracts:

if(contract is not yet deployed) {
   const mynewcontract = deployProxy(MyContract, {deployer});
} else {
   const myupgradedcontract = upgradeProxy(MyContract, {deployer});
}

How can I handle that or how can I check in the migration script if the contract has already been deployed?

Answer 1

First install,

npm install @openzeppelin/truffle-upgrades

In your migrations/2_deploy_contracts.js, I had to wrap around a try-catch because MyContract.deployed() was throwing an exception when the contract is not deployed.

const { deployProxy, upgradeProxy } = require('@openzeppelin/truffle-upgrades');
var MyContract = artifacts.require('./MyContract');
module.exports = async function(deployer) {
  try {
    var instance = await MyContract.deployed();
    var upgraded = await upgradeProxy(instance.address, MyContract, { deployer });
    console.log("Upgraded", upgraded.address);    
  } catch(error) {
    var instance = await deployProxy(MyContract, [], { deployer });
    console.log("Deployed", instance.address);    
}
}