Storing Custom Types

While native types can be stored in a contract's storage without any additional work, custom types require a bit more work. This is because at compile time, the compiler does not know how to store custom types in storage. To solve this, we need to implement the Store trait for our custom type. Hopefully, we can just derive this trait for our custom type - unless it contains arrays or dictionaries.

#[starknet::interface]
trait IStoringCustomType<TContractState> {
    fn set_person(ref self: TContractState, person: Person);
}

// Deriving the starknet::Store trait
// allows us to store the `Person` struct in the contract's storage.
#[derive(Drop, Serde, Copy, starknet::Store)]
struct Person {
    age: u8,
    name: felt252
}

#[starknet::contract]
mod StoringCustomType {
    use super::Person;

    #[storage]
    struct Storage {
        person: Person
    }

    #[abi(embed_v0)]
    impl StoringCustomType of super::IStoringCustomType<ContractState> {
        fn set_person(ref self: ContractState, person: Person) {
            self.person.write(person);
        }
    }
}

Play with this contract in Remix.