# The contract state

Each contract has access to a sandboxed state for storage of data. The write actions on the state are rolled back in case the contract operation returns an error. If a transaction is successfully committed, it contains the hash of the state root so that any given state is committed to the blockchain.

# Writing to the state

Use the Set operation on the contract context to save to the state.

Set(key []byte, pb proto.Message) error

go-loom mandates that the data being saved is a protobuf object.

# Reading from the state

Use the Has operation to check whether a particular key exists in the state

Has(key []byte) bool

To read the value saved at a key, use the Get operation

Get(key []byte, pb proto.Message) error

Get will unmarshal the saved data into a protobuf struct.

# Deleting a key

Data saved at a key can be deleted with

Delete(key []byte)