> ## Documentation Index
> Fetch the complete documentation index at: https://docs.starknet.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Custom types in entrypoints

When using custom types in Starknet contract entrypoints, you need to handle serialization and deserialization of data. This is because:

1. Input parameters are sent to entrypoints as arrays of `felt252`
2. Return values must be converted back to arrays of `felt252`
3. Custom types need to be converted between these formats automatically

## Using the Serde Trait

The `Serde` trait provides the necessary serialization and deserialization capabilities for your custom types. For most simple types, you can derive this trait automatically:

```rust theme={null}
#[derive(Drop, starknet::Serde)]
struct Person {
    name: felt252,
    age: u8,
    is_active: bool,
}

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

#[starknet::contract]
mod CustomTypeEntrypoints {
    use starknet::storage::{StoragePointerReadAccess, StoragePointerWriteAccess};

    #[storage]
    struct Storage {
        person: Person,
    }

    #[abi(embed_v0)]
    impl CustomTypeEntrypoints of super::ICustomTypeEntrypoints<ContractState> {
        fn set_person(ref self: ContractState, person: Person) {
            // The Serde trait automatically handles serialization of the Person struct
            self.person.write(person);
        }

        fn get_person(self: @ContractState) -> Person {
            // The Serde trait automatically handles deserialization of the Person struct
            self.person.read()
        }
    }
}
```

<Note>
  For some complex types, you might need to implement the `Serde` trait manually. This gives you control over how your type is serialized and deserialized.

  The `Serde` trait is distinct from the `Store` trait - `Serde` is for passing data in and out of entrypoints, while `Store` is for persisting data in contract storage.
</Note>