NEAR

Non-fungible Token (NFT)

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Non-fungible Token (NFT)

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This repository includes an example implementation of a non-fungible token contract which uses near-contract-standards and simulation tests.

Prerequisites

If you're using Gitpod, you can skip this step.

  • Make sure Rust is installed per the prerequisites in near-sdk-rs.
  • Make sure near-cli is installed.

Explore this contract

The source for this contract is in nft/lib.rs. It provides methods to manage access to tokens, transfer tokens, check access, and get token owner. Note, some further exploration inside the rust macros is needed to see how the NonFungibleToken contract is implemented.

Building this contract

Run the following, and we'll build our rust project up via cargo. This will generate our WASM binaries into our res/ directory. This is the smart contract we'll be deploying onto the NEAR blockchain later.

./build.sh

Testing this contract

We have some tests that can be ran. The following will just run our simple tests to verify that our contract code is working.

cargo test -- --nocapture

The more complex simulation tests aren't ran with this command, but we can find them in tests/sim.

Using this contract

Quickest deploy

You can build and deploy this smart contract to a development account. Dev Accounts are auto-generated accounts to assist in developing and testing smart contracts. Please see the Standard deploy section for creating a more personalized account to deploy to.

near dev-deploy --wasmFile res/non_fungible_token.wasm --helperUrl https://near-contract-helper.onrender.com

Behind the scenes, this is creating an account and deploying a contract to it. On the console, notice a message like:

Done deploying to dev-1234567890123

In this instance, the account is dev-1234567890123. A file has been created containing a key pair to the account, located at neardev/dev-account. To make the next few steps easier, we're going to set an environment variable containing this development account id and use that when copy/pasting commands. Run this command to the environment variable:

source neardev/dev-account.env

You can tell if the environment variable is set correctly if your command line prints the account name after this command:

echo $CONTRACT_NAME

The next command will initialize the contract using the new method:

near call $CONTRACT_NAME new_default_meta '{"owner_id": "'$CONTRACT_NAME'"}' --accountId $CONTRACT_NAME

To view the NFT metadata:

near view $CONTRACT_NAME nft_metadata

Standard deploy

This smart contract will get deployed to your NEAR account. For this example, please create a new NEAR account. Because NEAR allows the ability to upgrade contracts on the same account, initialization functions must be cleared. If you'd like to run this example on a NEAR account that has had prior contracts deployed, please use the near-cli command near delete, and then recreate it in Wallet. To create (or recreate) an account, please follow the directions in Test Wallet or (NEAR Wallet if we're using mainnet).

In the project root, log in to your newly created account with near-cli by following the instructions after this command.

near login

To make this tutorial easier to copy/paste, we're going to set an environment variable for our account id. In the below command, replace MY_ACCOUNT_NAME with the account name we just logged in with, including the .testnet (or .near for mainnet):

ID=MY_ACCOUNT_NAME

We can tell if the environment variable is set correctly if our command line prints the account name after this command:

echo $ID

Now we can deploy the compiled contract in this example to your account:

near deploy --wasmFile res/non_fungible_token.wasm --accountId $ID

NFT contract should be initialized before usage. More info about the metadata at 'nomicon.io'. But for now, we'll initialize with the default metadata.

near call $ID new_default_meta '{"owner_id": "'$ID'"}' --accountId $ID

We'll be able to view our metadata right after:

near view $ID nft_metadata

Then, let's mint our first token. This will create a NFT based on Olympus Mons where only one copy exists:

near call $ID nft_mint '{"token_id": "0", "receiver_id": "'$ID'", "token_metadata": { "title": "Olympus Mons", "description": "Tallest mountain in charted solar system", "media": "https://upload.wikimedia.org/wikipedia/commons/thumb/0/00/Olympus_Mons_alt.jpg/1024px-Olympus_Mons_alt.jpg", "copies": 1}}' --accountId $ID --deposit 10

Transferring our NFT

Let's set up an account to transfer our freshly minted token to. This account will be a sub-account of the NEAR account we logged in with originally via near login.

near create-account alice.$ID --masterAccount $ID --initialBalance 10

Checking Alice's account for tokens:

near view $ID nft_tokens_for_owner '{"account_id": "'alice.$ID'"}'

Then we'll transfer over the NFT into Alice's account. Exactly 1 yoctoNEAR of deposit should be attached:

near call $ID nft_transfer '{"token_id": "0", "receiver_id": "alice.'$ID'", "memo": "transfer ownership"}' --accountId $ID --deposit 0.000000000000000000000001

Checking Alice's account again shows us that she has the Olympus Mons token.

Notes

  • The maximum balance value is limited by U128 (2**128 - 1).
  • JSON calls should pass U128 as a base-10 string. E.g. "100".
  • This does not include escrow functionality, as ft_transfer_call provides a superior approach. An escrow system can, of course, be added as a separate contract or additional functionality within this contract.

AssemblyScript

Currently, AssemblyScript is not supported for this example. An old version can be found in the NEP4 example, but this is not recommended as it is out of date and does not follow the standards the NEAR SDK has set currently.

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