Minting Compressed NFTs

Summary

Minting compressed NFTs adds new cNFTs to a Bubblegum Tree using the mintV2 instruction. This page covers minting with and without MPL-Core collections, and retrieving the asset ID from mint transactions.

• Mint cNFTs to a Bubblegum Tree using the mintV2 instruction
• Mint directly into an MPL-Core collection with the BubblegumV2 plugin
• Retrieve the asset ID and leaf schema from the mint transaction
• Configure metadata including name, URI, creators, and royalties

In the previous page, we saw that we need a Bubblegum Tree to mint Compressed NFTs, and we saw how to create one. Now, let's see how to mint compressed NFTs from a given Bubblegum Tree.

The Bubblegum program offers multiple minting instructions for the different leaf schema versions. Bubblegum V2 introduces a new minting instruction called mintV2 that is used to mint Compressed NFTs either to a given Collection or without a Collection.

Minting without a Collection

The Bubblegum program provides the mintV2 instruction that enables us to mint Compressed NFTs from a Bubblegum Tree. If the Bubblegum Tree is public, anyone will be able to use this instruction. Otherwise, only the Tree Creator or the Tree Delegate will be able to do so.

The main parameters of the mintV2 instruction are:

• Merkle Tree: The Merkle Tree address from which the Compressed NFT will be minted.
• Tree Creator Or Delegate: The authority allowed to mint from the Bubblegum Tree — this can either be the creator or the delegate of the tree. This authority must sign the transaction. In the case of a public tree, this parameter can be any authority, but must still be a signer.
• Leaf Owner: The owner of the Compressed NFT that will be minted. It defaults to the payer of the transaction.
• Leaf Delegate: A delegate authority allowed to manage the minted cNFT, if any. Otherwise, it is set to the Leaf Owner.
• Collection Authority: The authority allowed to manage the given Collection.
• Core Collection: The MPL-Core Collection NFT to which the Compressed NFT will be added.
• Metadata: The metadata of the Compressed NFT that will be minted. It contains information such as the Name of the NFT, its URI, its Collection, its Creators, etc. In Bubblegum V2 the metadata is using MetadataArgsV2 which excludes unneeded fields like uses and the verified flag for the collection.

import { none } from '@metaplex-foundation/umi';
import { mintV2 } from '@metaplex-foundation/mpl-bubblegum';

await mintV2(umi, {
  leafOwner: umi.identity.publicKey,
  merkleTree: merkleTree.publicKey,
  metadata: {
    name: 'My NFT',
    uri: 'https://example.com/my-nft.json',
    sellerFeeBasisPoints: 550, 
    collection: none(),
    creators: [],
  },
}).sendAndConfirm(umi);

Minting to a Collection

While it is possible to set and verify a Collection for a Compressed NFT after it is minted, Bubblegum V2 allows you to mint a Compressed NFT directly to a given Collection. Bubblegum V2 uses MPL-Core Collections to group the compressed NFTs. The same mintV2 instruction is used for that. In addition to the parameters described above, you need to pass in the core collection and sign as collection authority or delegate:

• Core Collection: The mint address passed to the coreCollection parameter, pointing to the MPL-Core Collection NFT…
• Collection Authority: The authority allowed to manage the given Collection NFT. This can either be the update authority of the Collection NFT or a delegated collection authority. This authority must sign the transaction regardless of whether the Bubblegum Tree is public or not.

Note that the Metadata parameter must contain the Collection Public Key.

import { some } from '@metaplex-foundation/umi';
import { mintV2 } from '@metaplex-foundation/mpl-bubblegum';

await mintV2(umi, {
  collectionAuthority: umi.identity,
  leafOwner: umi.identity.publicKey,
  merkleTree: merkleTree.publicKey,
  coreCollection: collectionSigner.publicKey,
  metadata: {
    name: 'My NFT',
    uri: 'https://example.com/my-nft.json',
    sellerFeeBasisPoints: 550, // 5.5%
    collection: some(collectionSigner.publicKey),
    creators: [],
  },
}).sendAndConfirm(umi);

Get Asset ID and Leaf Schema from mint transaction

You can retrieve the leaf and determine the asset ID from the mintV2 transaction using the parseLeafFromMintV2Transaction helper. This function parses the Transaction, therefore you have to make sure that it has been finalized before calling parseLeafFromMintV2Transaction.

import {
  mintV2,
  parseLeafFromMintV2Transaction,
} from '@metaplex-foundation/mpl-bubblegum';

const { signature } = await mintV2(umi, {
  // ... see details above
}).sendAndConfirm(umi);

const leaf = await parseLeafFromMintV2Transaction(umi, signature);
const assetId = leaf.id;

Notes

• The Bubblegum Tree must be created before minting. See Creating Trees.
• For collection mints, the MPL-Core collection must have the BubblegumV2 plugin enabled.
• The collection authority must sign the transaction when minting to a collection, regardless of whether the tree is public or private.
• Use parseLeafFromMintV2Transaction only after the transaction is finalized, not just confirmed.

FAQ

How do I mint a compressed NFT to a collection?

Use the mintV2 instruction with the coreCollection parameter set to your MPL-Core collection address and provide the collectionAuthority signer. The collection must have the BubblegumV2 plugin enabled.

How do I get the asset ID after minting?

Use the parseLeafFromMintV2Transaction helper after the transaction is finalized. It parses the transaction and returns the leaf schema including the asset ID via leaf.id.

Can anyone mint from my tree?

Only if the tree was created with public: true. For private trees, only the Tree Creator or Tree Delegate can mint cNFTs.

What metadata fields are required for minting?

The MetadataArgsV2 struct requires: name (string), uri (string pointing to JSON metadata), sellerFeeBasisPoints (0-10000), collection (public key or none), and creators (array of creator objects).

Glossary