Minting Compressed NFTs

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;