Build an NFT post-condition

Create post-conditions for NFT transfers to ensure specific tokens are or aren't transferred

import { Pc, Cl } from '@stacks/transactions';



// Ensure a specific NFT will be sent

const sendPC = Pc.principal("ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM")

  .willSendAsset()

  .nft('ST1HTBVD3JG9C05J7HBJTHGR0GGW7KXW28M5JS8QE.cool-nfts::nft-token', Cl.uint(42));



// Ensure a specific NFT will NOT be sent

const keepPC = Pc.principal("ST1PQHQKV0RJXZFY1DGX8MNSNYVE3VGZJSRTPGZGM")

  .willNotSendAsset()

  .nft('ST1HTBVD3JG9C05J7HBJTHGR0GGW7KXW28M5JS8QE.cool-nfts::nft-token', Cl.uint(1));

Use cases

  • Protecting valuable NFTs from accidental transfers
  • Ensuring specific NFTs are transferred in marketplace transactions
  • Safeguarding NFT collections during contract interactions

Key concepts

NFT post-conditions use the .nft() method which requires:

  • Asset identifier: Contract address + asset name with :: separator
  • Token ID: The specific NFT ID as a Clarity value (using Cl.uint())

NFT post-condition types

// Will send a specific NFT

const willSend = Pc.principal(address)

  .willSendAsset()

  .nft(assetIdentifier, tokenId);



// Will NOT send a specific NFT

const willNotSend = Pc.principal(address)

  .willNotSendAsset()

  .nft(assetIdentifier, tokenId);

Complete example

import {

  AnchorMode,

  Cl,

  makeContractNonFungiblePostCondition,

  NonFungibleConditionCode,

  Pc,

  PostConditionMode,

  createAssetInfo,

} from '@stacks/transactions';



// Define the NFT details

const nftContract = 'ST1HTBVD3JG9C05J7HBJTHGR0GGW7KXW28M5JS8QE.art-gallery';

const nftAsset = 'artwork';

const tokenId = Cl.uint(123);



// Using the Pc builder

const nftPostCondition = Pc.principal(senderAddress)

  .willSendAsset()

  .nft(`${nftContract}::${nftAsset}`, tokenId);



// Alternative: Using the standard function

const altPostCondition = makeContractNonFungiblePostCondition(

  senderAddress,

  nftContract,

  NonFungibleConditionCode.Sends,

  createAssetInfo(nftContract.split('.')[0], nftContract.split('.')[1], nftAsset),

  tokenId

);



// Use in transaction

const txOptions = {

  // ... other options

  postConditions: [nftPostCondition],

  postConditionMode: PostConditionMode.Deny,

};

Package installation

Terminal
$ 
npm install @stacks/transactions

On this page

Use casesKey conceptsNFT post-condition typesComplete examplePackage installationRelated snippets