Modify contract.rs

1. Open the contract.rs file and uncomment the following lines:

/ const CONTRACT_NAME: &str = "crates.io:cw-starter"; const CONTRACT_VERSION: &str = env!("CARGO_PKG_VERSION"); /

2. Enable storage of contracts using cw2 standard:

use cosmwasm_std::{Binary, Deps, DepsMut, Env, MessageInfo, Response, StdResult};
use cw2::set_contract_version;

3. Use it in the instantiate method

#[cfg_attr(not(feature = "library"), entry_point)]
pub fn instantiate(
    deps: DepsMut, // ensure you remove the preceeding _. _deps -> deps
    _env: Env,
    _info: MessageInfo,
    _msg: InstantiateMsg,
) -> Result<Response, ContractError> {
    set_contract_version(deps.storage, CONTRACT_NAME, CONTRACT_VERSION)?;
    unimplemented!()
}

4. Let's create our Config struct and store it. Be sure to import the struct itself and the storage:

use crate::state::{Config, CONFIG};

5. Let's implement the logic to create an admin or not:

#[cfg_attr(not(feature = "library"), entry_point)]
pub fn instantiate(
    deps: DepsMut,
    _env: Env,
    info: MessageInfo, // removed _
    msg: InstantiateMsg, // removed _
) -> Result<Response, ContractError> {
    set_contract_version(deps.storage, CONTRACT_NAME, CONTRACT_VERSION)?;
    let admin = msg.admin.unwrap_or(info.sender.to_string());
    let validated_admin = deps.api.addr_validate(&admin)?;
    let config = Config {
        admin: validated_admin.clone(),
    };
    CONFIG.save(deps.storage, &config)?;
    Ok(Response::new()
        .add_attribute("action", "instantiate")
        .add_attribute("admin", validated_admin.to_string()))
}