Commodities Fabric Module: NFTs for Tetcore

This is a Tetcore module that defines and implements an interface for managing a set of non-fungible tokens (NFTs). Assets have an owner and can be created, destroyed, and transferred.

Interface

This package defines a public module for working with NFTs, providing functionality for:

• Collections: Create and manage NFT collections with optional max supply
• Minting: Create new NFTs within collections
• Burning: Destroy NFTs
• Transferring: Transfer ownership between accounts
• Approvals: Approve operators to transfer on behalf of owners
• Marketplace: List NFTs for sale, buy listings

Architecture

Core Types

• CollectionId: Unique identifier for an NFT collection
• NftId: Unique identifier for an individual NFT within a collection
• AssetId: Composite identifier combining collection and NFT IDs
• AssetInfo: Metadata including name, description, image URI, attributes
• Collection: Collection configuration including owner, max supply, royalty

Storage

The module maintains:

• collections: Map of all collections
• nfts: Map of all NFT data
• ownership: Map of asset ownership
• listings: Active marketplace listings

Usage

Creating a Collection

let mut nft_module = NftModule::new();

let collection_id = nft_module.create_collection(
    "My Collection".to_string(),
    "Description of my collection".to_string(),
    owner_address,
    Some(10000), // max supply
)?;

Minting an NFT

let asset_id = nft_module.mint(
    collection_id,
    recipient_address,
    AssetInfo::new("NFT Name".to_string(), "Description".to_string())
        .with_image("ipfs://...".to_string())
        .add_attribute("rarity".to_string(), "legendary".to_string()),
)?;

Transferring

nft_module.transfer(&asset_id, from_address, to_address)?;

Marketplace Listing

nft_module.list(
    asset_id,
    seller_address,
    1000, // price
    currency_address,
    expires_at_block,
)?;

Traits

UniqueAssets Trait

This module implements a variation of the UniqueAssets trait:

• total() -> u64: Total number of NFTs
• owner_of(AssetId) -> Address: Get owner of an NFT
• mint() -> Result<AssetId>: Create new NFT
• burn(AssetId): Destroy NFT
• transfer(AssetId, Address, Address): Transfer ownership

Design Decisions

Sorted Storage

This implementation uses sorted lists of assets per owner for efficient trading. Assets are sorted by ID to enable:

• Fast lookups during transfer
• Efficient burning operations
• Ordered enumeration

Marketplace

Built-in marketplace functionality supports:

• Fixed-price listings
• Expiration times
• Royalty support for collections

Tests

The module includes comprehensive tests:

cargo test

Run specific test modules:

cargo test --lib nft

Integration

To integrate this module into your Tetcore runtime:

1. Add to your Cargo.toml:

tetcore-mod-nft = { path = "../tetcore-mod-nft" }

2. Configure in your runtime:

impl tetcore_mod_nft::Config for Runtime { ... }

3. Add to runtime composition

Acknowledgements

This project was inspired by works such as:

• The ERC-721 specification
• OpenZeppelin's ERC-721 implementation
• Substrate's NFT pallet
• The original Substratekitties project
• danforbes' pallet-nft

License

See LICENSE file.