Trait ContractMessageDecoder

pub trait ContractMessageDecoder {
    type Type: Decode + ExecuteDispatchable;
}

Generated type used to decode all dispatchable ink! messages of the ink! smart contract.

Note

The decoder follows the ink! calling ABI where all ink! message calls start with 4 bytes dedicated to the ink! message selector followed by the SCALE encoded parameters.

Usage

#[ink::contract]
pub mod contract {
    #[ink(storage)]
    pub struct Contract {}

    impl Contract {
        #[ink(constructor)]
        pub fn constructor() -> Self {
            Self {}
        }

        #[ink(message)]
        pub fn message1(&self) {}

        #[ink(message)]
        pub fn message2(&self, input1: bool, input2: i32) {}
    }
}

use contract::Contract;

fn main() {
    // Call to `message1` without input parameters.
    {
        let mut input_bytes = Vec::new();
        input_bytes.extend(selector_bytes!("message1"));
        assert!(
            <<Contract as ContractMessageDecoder>::Type as Decode>::decode(
                &mut &input_bytes[..]
            )
            .is_ok()
        );
    }
    // Call to `message2` with 2 parameters.
    {
        let mut input_bytes = Vec::new();
        input_bytes.extend(selector_bytes!("message2"));
        input_bytes.extend(true.encode());
        input_bytes.extend(42i32.encode());
        assert!(
            <<Contract as ContractMessageDecoder>::Type as Decode>::decode(
                &mut &input_bytes[..]
            )
            .is_ok()
        );
    }
    // Call with invalid ink! message selector.
    {
        let mut input_bytes = Vec::new();
        input_bytes.extend(selector_bytes!("non_existing_message"));
        assert!(
            <<Contract as ContractMessageDecoder>::Type as Decode>::decode(
                &mut &input_bytes[..]
            )
            .is_err()
        );
    }
    // Call with invalid ink! message parameters.
    {
        let mut input_bytes = Vec::new();
        input_bytes.extend(selector_bytes!("message2"));
        assert!(
            <<Contract as ContractMessageDecoder>::Type as Decode>::decode(
                &mut &input_bytes[..]
            )
            .is_err()
        );
    }
}

Required Associated Types

type Type: Decode + ExecuteDispatchable

The ink! smart contract message decoder type.

Implementors