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Upgrade Smart Contracts

This example shows how to upgrade a contract to a new version while preserving its state:

#[test]
fn migration() -> Result<(), Error> {
let vm = VM::ephemeral()?;
let mut session = vm.session(SessionData::builder())?;
let contract = session.deploy(contract_bytecode!("counter"), ContractData::builder().owner(OWNER), LIMIT)?;
session.call::<_, ()>(contract, "increment", &(), LIMIT)?;
session.call::<_, ()>(contract, "increment", &(), LIMIT)?;
let root = session.commit()?;
let mut session = vm.session(SessionData::builder().base(root))?;
session = session.migrate(contract, contract_bytecode!("double_counter"), ContractData::builder(), LIMIT, |new_contract, session| {
let old_counter_value = session.call::<_, i64>(contract, "read_value", &(), LIMIT)?.data;
let (left_counter_value, _) = session.call::<_, (i64, i64)>(new_contract, "read_values", &(), LIMIT)?.data;
let diff = old_counter_value - left_counter_value;
for _ in 0..diff {
session.call::<_, ()>(new_contract, "increment_left", &(), LIMIT)?;
}
Ok(())
})?;
let root = session.commit()?;
let mut session = vm.session(SessionData::builder().base(root))?;
let (left_counter, right_counter) = session.call::<_, (i64, i64)>(contract, "read_values", &(), LIMIT)?.data;
assert_eq!(left_counter, 0xfe);
assert_eq!(right_counter, 0xcf);
Ok(())
}

The following example shows how to modify metadata attributes like OWNER:

#[test]
fn migration_new_owner() -> Result<(), Error> {
let vm = VM::ephemeral()?;
let mut session = vm.session(SessionData::builder())?;
const OWNER: [u8; 33] = [1u8; 33];
const NEW_OWNER: [u8; 33] = [2u8; 33];
let contract = session.deploy(contract_bytecode!("counter"), ContractData::builder().owner(OWNER), LIMIT)?;
let root = session.commit()?;
let mut session = vm.session(SessionData::builder().base(root))?;
session = session.migrate(contract, contract_bytecode!("metadata"), ContractData::builder().owner(NEW_OWNER), LIMIT, |_, _| Ok(()))?;
let owner = session.call::<_, [u8; 33]>(contract, "read_owner", &(), LIMIT)?.data;
assert_eq!(owner, NEW_OWNER);
Ok(())
}