Skip to main content

PSP35 Metadata

This example shows how you can reuse the implementation of PSP35 token with PSP35Metadata extension.

Step 1: Add imports and enable unstable feature​

Import everything from openbrush::contracts::psp35::extensions::metadata.

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

#[openbrush::contract]
pub mod my_psp35 {
    use openbrush::contracts::psp35::extensions::metadata::*;
    use ink_prelude::string::String;
    use ink_storage::traits::SpreadAllocate;
...

Step 2: Define storage​

Declare storage struct and declare the field related to the PSP35MetadataStorage trait in addition to your PSP35Storage field. Then you need to derive the PSP35MetadataStorage trait and mark the corresponding field with the #[PSP35MetadataStorageField] attribute. Deriving this trait allows you to reuse the PSP35Metadata extension in your PSP35 implementation.

#[derive(Default, SpreadAllocate, PSP35Storage, PSP35MetadataStorage)]
#[ink(storage)]
pub struct MyPSP35 {
    #[PSP35StorageField]
    psp35: PSP35Data,
    #[PSP35MetadataStorageField]
    metadata: PSP35MetadataData,
}

Step 3: Inherit logic​

Inherit implementation of the PSP35Metadata trait. You can customize (override) methods in this impl block.


impl PSP35 for MyPSP35 {}

impl PSP35Metadata for MyPSP35 {}

Step 4: Define constructor​

Define constructor. Your PSP35Metadata contract is ready!

impl MyPSP35 {
    #[ink(constructor)]
    pub fn new(id: Id, key: Vec<u8>, attribute: Vec<u8>) -> Self {
        ink_lang::codegen::initialize_contract(|instance: &mut Self| {
            instance.metadata.attributes.insert(&(id, key), &attribute);
        })
    }
}

You can check an example of the usage of PSP35 Metadata.

You can also check the documentation for the basic implementation of PSP35.