PSP34 Metadata

This example shows how you can reuse the implementation of PSP34 token with PSP34Metadata extension.

First, you should implement basic version of PSP34.

Step 1: Add imports and enable unstable feature

Use openbrush::contract macro instead of ink::contract. Import everything from openbrush::contracts::psp34::extensions::metadata.

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

#[openbrush::contract]
pub mod my_psp34_metadata {
    use openbrush::contracts::psp34::extensions::metadata::*;
...

Step 2: Define storage

Declare storage struct and declare the field related to the metadata module data structure. Then you need to derive the Storage trait and mark the corresponding field with the #[storage_field] attribute. Deriving this trait allows you to reuse the PSP34Metadata extension in your PSP34 implementation.

#[ink(storage)]
#[derive(Default, SpreadAllocate, Storage)]
pub struct Contract {
    ...
    #[storage_field]
    metadata: metadata::Data,
}

Step 3: Inherit logic

Inherit implementation of the PSP34Metadata trait. You can customize (override) methods in this impl block.

impl PSP34Metadata for Contract {}

Step 4: Define constructor

Define constructor. Your PSP34Metadata contract is ready!

impl Contract {
    #[ink(constructor)]
    pub fn new(id: Id, name: String, symbol: String) -> Self {
        ink_lang::codegen::initialize_contract(|instance: &mut Self| {
            instance._set_attribute(id.clone(), String::from("name"), name);
            instance._set_attribute(id, String::from("symbol"), symbol);
        }
    }
}

Final code

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

#[openbrush::contract]
pub mod my_psp34_metadata {
    use openbrush::traits::String;
    use ink_prelude::{
        vec::Vec,
    };
    use ink_storage::traits::SpreadAllocate;
    use openbrush::{
        contracts::psp34::extensions::metadata::*,
        traits::Storage,
    };

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

    impl PSP34 for Contract {}

    impl PSP34Metadata for Contract {}

    impl Contract {
        /// A constructor which mints the first token to the owner
        #[ink(constructor)]
        pub fn new(id: Id, name: String, symbol: String) -> Self {
            ink_lang::codegen::initialize_contract(|instance: &mut Self| {
                let name_key: Vec<u8> = String::from("name");
                let symbol_key: Vec<u8> = String::from("symbol");
                instance._set_attribute(id.clone(), name_key, name);
                instance._set_attribute(id, symbol_key, symbol);
            })
        }
    }
}

You can check an example of the usage of PSP34 Metadata.

You can also check the documentation for the basic implementation of PSP34.