This example demonstrates implementing an NFT canister. NFTs (non-fungible tokens) are unique tokens with arbitrary metadata, usually an image of some kind, to form the digital equivalent of trading cards. There are a few different NFT standards for the Internet Computer (e.g EXT, IC-NFT), but for the purposes of this tutorial we use DIP-721. You can see a quick introduction on YouTube.
The canister is a basic implementation of the standard, with support for the minting, burning, and notification interface extensions.
The NFT canister is not very complicated since the DIP-721 standard specifies most CRUD operations, but we can still use it to explain three important concepts concerning dapp development for the Internet Computer:
A running instance of the Rust canister for demonstration purposes is available as t5l7c-7yaaa-aaaab-qaehq-cai.
The interface is meant to be programmatic, but the Rust version additionally contains HTTP functionality so you can view a metadata file at <canister URL>/<NFT ID>/<file ID>.
It contains six NFTs, so you can look at items from <canister URL>/0/0 to <canister URL>/5/0.
- Install the IC SDK.
- Download and install git.
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wasm32-unknown-unknowntargets; these can be installed withrustup target add wasm32-unknown-unknown.
init(args: InitArgs): Initializes the canister with given arguments.pre_upgrade(): Prepares and serializes the canister's state before an upgrade.post_upgrade(): Restores the canister's state after an upgrade.
mint(to: Principal, metadata: MetadataDesc, blob_content: Vec<u8>): Mints a new NFT.burn(token_id: u64): Burns (destroys) an NFT.
transfer_from(from: Principal, to: Principal, token_id: u64): Transfers an NFT from one principal to another.safe_transfer_from(from: Principal, to: Principal, token_id: u64): Safely transfers an NFT, checking for zero addresses.transfer_from_notify(from: Principal, to: Principal, token_id: u64, data: Vec<u8>): Transfers an NFT and notifies the recipient.safe_transfer_from_notify(from: Principal, to: Principal, token_id: u64, data: Vec<u8>): Safely transfers an NFT with notification.
approve(user: Principal, token_id: u64): Approves a user to manage a specific NFT.set_approval_for_all(operator: Principal, is_approved: bool): Sets or unsets approval for an operator to manage all NFTs of the caller.is_approved_for_all(operator: Principal): Checks if an operator is approved for all NFTs of the caller.set_custodian(user: Principal, custodian: bool): Adds or removes a custodian.is_custodian(principal: Principal): Checks if a principal is a custodian.
balance_of(user: Principal): Returns the number of NFTs owned by a user.owner_of(token_id: u64): Returns the owner of a specific NFT.name(): Returns the name of the NFT collection.symbol(): Returns the symbol of the NFT collection.total_supply(): Returns the total number of NFTs minted.supported_interfaces(): Lists the supported interfaces (DIP721 standards).get_metadata(token_id: u64): Retrieves metadata for a specific NFT.get_metadata_for_user(user: Principal): Retrieves metadata for all NFTs owned by a user.
set_name(name: String): Sets the name of the NFT collection.set_symbol(sym: String): Sets the symbol of the NFT collection.set_logo(logo: Option<LogoResult>): Sets the logo for the NFT collection.
The sample code is available in the samples repository in Rust
This Rust example comes with a demo script, demo.sh, which runs through an example workflow with minting and trading an NFT between a few users. This is primarily designed to be read rather than run so that you can use it to see how basic NFT operations are done. For a more in-depth explanation, read the [standard][DIP721].
First, open the Terminal application on your Mac. You can find it in the Applications folder under Utilities, or you can search for it using Spotlight.
Before running the script, you need to make sure it is executable. You can do this by running the following command:
chmod +x demo.sh### 3- Run the Script Now, you can run the script by typing:
./demo.sh