Unique docs

Collection sponsoring

In Unique Network, transactions can be sponsored, allowing for a gasless experience where the sponsor covers the transaction fees. This enables seamless and cost-free transfers of NFTs and the execution of smart contracts, even for accounts without native tokens.

Prerequisite

Follow the Getting started guide to install required libraries, receive test network OPL tokens, and initialize SDK.

At this point, you need to know how to manage collections. Learn how to do this in the Working with collections guide.

You also need to know how to mint and transfer NFTs.

Setting collection sponsoring

The process consists of two steps:

  1. Set collection sponsor – only the collection owner or admin can do
  2. Confirm sponsorship. The sponsor should confirm willingness to sponsor a collection
// At this point we assume you already have a minted collection and NFT
const collectionId = ...
const tokenId = ...

await sdk.collection.setSponsor({collectionId, sponsor: account.address})
await sdk.collection.confirmSponsorship({collectionId});

At this point, every action with tokens of this collection, such as transfer or minting, will be sponsored by account.

Setting limits

You may want to set limits on sponsorship to prevent your sponsorship account from being drained. We already discussed how to set limits in the collection section. Let's take a closer look on sponsorship-related limits.

await sdk.collection.create({
  name: "Test",
  description: "Test collection",
  symbol: "TST",
  limits: {
    // The time interval in blocks defines once per how long a non-privileged user approve transaction can be sponsored.
    sponsorApproveTimeout: 100,
    // Defines how many blocks need to pass between setVariableMetadata transactions in order for them to be sponsored
    sponsoredDataRateLimit: 100,
    // The maximum byte size of custom token data that can be sponsored when tokens are minted in sponsored mode
    sponsoredDataSize: 2048,
    // The time interval in blocks that defines once per how long a non-privileged user transfer or mint transaction can be sponsored
    sponsorTransferTimeout: 0,
  },
});

Let's check that an account without native tokens can transfer NFT

// generate a new account without OPL
const emptyAccount = Sr25519Account.fromUri(Sr25519Account.generateMnemonic());

// mint new token directly to `emptyAccount`
const tokensCreation = await sdk.token.mintNFTs({collectionId, tokens: [
 {owner: account.address}
]});
const [token] = tokensCreation.result;

// emptyAccount makes transfer
await sdk.token.transfer(
  {
    to: alice.address,
    collectionId,
    tokenId: token.tokenId,
  },
  { signerAddress: emptyAccount.address },
  emptyAccount,
);

// Check alice is the new owner
const { owner } = await sdk.token.get({
  collectionId: collectionId,
  tokenId: token.tokenId,
});