Why do we need an Interface or the contract in ethers.getContractAt() function?

Question

As per my understanding, if we want to get or interract with an already deployed contract, we can use this ethers.getContractAt() function.

But since it's already deployed, can't we just give the contract name and address to get it? Is it compulsory to have the contract (here, ILendingPoolAddressesProvider.sol) code in my local folder too?

And also, why am I attaching an account with it, since it has been deployed already?

There might be some mistakes in my basic understanding. Kindly explain.

const lendingPoolAddressesProvider = await ethers.getContractAt(
            "ILendingPoolAddressesProvider",
            "0xB53C1a33016B2DC2fF3653530bfF1848a515c8c5",
            account
            )

Answer 1

If you look at the documentation of ethers.getContractAt you will find this:

function getContractAt(name: string, address: string, signer?: ethers.Signer): Promise<ethers.Contract>;

Note: If there is no signer available, getContractAt returns read-only contracts.

The '?' in 'signer?: ethers.Signer' means that argument is optional. So you don't need to provide 'account'.

And by giving it the name of the contract. ether knows what ABI to use to talk to this contract (i.e. what function to use to talk to the contract). So name and address, or abi and address are the bare minimum.

Hope this helps!