PSP34

This example shows how you can reuse the implementation of PSP34 token. Also, this example shows how you can customize the logic, for example, to track the number of tokens minted with next_id, increasing it with each new token minted, securing a unique id for each token.

Step 1: Import default implementation

With default Cargo.toml, you need to enable psp34 feature, embed modules data structures and implement them via #[openbrush::implementation] macro as described in that section.

The main trait is PSP34.

Step 2: Define constructor

Define empty constructor.

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

Step 3: Customize your contract

Customize it by adding logic for tracking the number of minted tokens. It will contain a custom mint_token function which will handle the id of the newly minted token. Also, we will add the next_id: u8 field to the structure, which will be increased with each newly minted token. This way we will make sure there will always be added a token with a unique id.

#![cfg_attr(not(feature = "std"), no_std, no_main)]

#[openbrush::implementation(PSP34)]
#[openbrush::contract]
pub mod my_psp34 {
    use openbrush::traits::Storage;

    #[ink(storage)]
    #[derive(Default, Storage)]
    pub struct Contract {
        #[storage_field]
        psp34: psp34::Data,
        next_id: u8,
    }

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

        #[ink(message)]
        pub fn mint_token(&mut self) -> Result<(), PSP34Error> {
            psp34::Internal::_mint_to(self, Self::env().caller(), Id::U8(self.next_id))?;
            self.next_id += 1;
            Ok(())
        }

        #[ink(message)]
        pub fn mint(&mut self, id: Id) -> Result<(), PSP34Error> {
            psp34::Internal::_mint_to(self, Self::env().caller(), id)
        }
    }
}

You can check an example of the usage of PSP34. Also you can use extensions for psp34 token:

PSP34Metadata: metadata for PSP34.

PSP34Mintable: creation of new tokens.

PSP34Burnable: destruction of contract's tokens.

PSP34Enumerable: iterating over contract's tokens.