Truffle Migrate

Question

What happens when there is a minor change in the smart contract and I run truffle migrate command.

Example:

//before
contract test{
    function display() public returns (string){
       return "message";
    }   
 }

//after
contract test{
    uint temp; //new var
    function display() public returns (string){
       return "updated message"; //changed message
    }   
 }

Ideally, it should deploy the smart contract in a different address. However, in the console, it says: Everything is up to date, there is nothing to compile. Also, in ganache, I don't see a contract creation transaction. Although, in the contracts section of ganache, I can see new storage variable "temp". How is it possible if the new contract is not deployed?

Answer 1

Yes, your contract was not deployed. To deploy your new contract you have to use truffle migrate --reset. Be aware that the contract is deployed at a new address and the old contract still remains on the blockchain.

To "override" your current contract (in reality it's not overriden) you have to use the Proxy Pattern. OpenZeppelin provides a good explanation of this: https://docs.openzeppelin.com/upgrades/