PSP37

This example shows how you can reuse the implementation of PSP37 token. Also, this example shows how you can customize the logic, for example, to track the number of token types with unique_ids, adding a new token type with the add_type function.

Step 1: Import default implementation

With default Cargo.toml, you need to enable psp37 feature, embed modules data structures and implement them via #[openbrush::implementation] macro as described in that section.

The main trait is PSP37.

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 denying of minting some tokens. We can deny minting of token with id by deny function. Id will be added to denied_ids map. If someone tries to mint token with denied id, we will reject transaction.

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

#[openbrush::implementation(PSP37)]
#[openbrush::contract]
pub mod my_psp37 {
    use ink::prelude::vec;
    use openbrush::{
        storage::Mapping,
        traits::{
            Storage,
            String,
        },
    };

    #[derive(Default, Storage)]
    #[ink(storage)]
    pub struct Contract {
        #[storage_field]
        psp37: psp37::Data,
        denied_ids: Mapping<Id, ()>,
    }

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

        #[ink(message)]
        pub fn deny(&mut self, id: Id) {
            self.denied_ids.insert(&id, &());
        }

        #[ink(message)]
        pub fn mint_tokens(&mut self, id: Id, amount: Balance) -> Result<(), PSP37Error> {
            if self.denied_ids.get(&id).is_some() {
                return Err(PSP37Error::Custom(String::from("Id is denied")))
            }
            psp37::Internal::_mint_to(self, Self::env().caller(), vec![(id, amount)])
        }
    }
}

You can check an example of the usage of PSP37.

Also you can use extensions for PSP37 token:

PSP37Metadata: metadata for PSP37.

PSP37Mintable: creation of new tokens.

PSP37Burnable: destruction of contract's tokens.

PSP37Batch: transfer batch of tokens.

PSP37Enumerable: iterates over contract's tokens.