Example usage of the TS SDK

Install

npm install --save @solana/spl-account-compression @solana/web3.js

OR

yarn add @solana/spl-account-compression @solana/web3.js

Examples

1. Create a tree

// Assume: known `payer` Keypair
// Generate a keypair for the ConcurrentMerkleTree
const cmtKeypair = Keypair.generate();
// Create a system instruction to allocate enough 
// space for the tree
const allocAccountIx = await createAllocTreeIx(
    connection,
    cmtKeypair.publicKey,
    payer.publicKey,
    { maxDepth, maxBufferSize },
    canopyDepth,
);
// Create an SPL compression instruction to initialize
// the newly created ConcurrentMerkleTree
const initTreeIx = createInitEmptyMerkleTreeIx(
    cmtKeypair.publicKey, 
    payer.publicKey, 
    { maxDepth, maxBufferSize }
);
const tx = new Transaction().add(allocAccountIx).add(initTreeIx);
await sendAndConfirmTransaction(connection, tx, [cmtKeypair, payer]);

2. Add a leaf to the tree

// Create a new leaf
const newLeaf: Buffer = crypto.randomBytes(32);
// Add the new leaf to the existing tree
const appendIx = createAppendIx(cmtKeypair.publicKey, payer.publicKey, newLeaf);
const tx = new Transaction().add(appendIx);
await sendAndConfirmTransaction(connection, tx, [payer]);

3. Replace a leaf in the tree, using the provided MerkleTree as an indexer

This example assumes that offChainTree has been indexing all previous modifying transactions involving this tree. It is okay for the indexer to be behind by a maximum of maxBufferSize transactions.

// Assume: `offChainTree` is a MerkleTree instance
// that has been indexing the `cmtKeypair.publicKey` transactions
// Get a new leaf
const newLeaf: Buffer = crypto.randomBytes(32);
// Query off-chain records for information about the leaf
// you wish to replace by its index in the tree
const leafIndex = 314;
// Replace the leaf at `leafIndex` with `newLeaf`
const replaceIx = createReplaceIx(
    cmtKeypair.publicKey,          
    payer.publicKey,
    newLeaf,
    offChainTree.getProof(leafIndex) 
);
const tx = new Transaction().add(replaceIx);
await sendAndConfirmTransaction(connection, tx, [payer]);

4. Replace a leaf in the tree, using a 3rd party indexer

This example assumes that some 3rd party service is indexing the tree at cmtKeypair.publicKey for you, and providing MerkleProofs via some REST endpoint. The getProofFromAnIndexer function is a placeholder to exemplify this relationship.

// Get a new leaf
const newLeaf: Buffer = crypto.randomBytes(32);
// Query off-chain indexer for a MerkleProof
// possibly by executing GET request against a REST api
const proof = await getProofFromAnIndexer(myOldLeaf);
// Replace `myOldLeaf` with `newLeaf` at the same index in the tree
const replaceIx = createReplaceIx(
    cmtKeypair.publicKey,          
    payer.publicKey,
    newLeaf,
    proof
);
const tx = new Transaction().add(replaceIx);
await sendAndConfirmTransaction(connection, tx, [payer]);

Reference examples

Here are some examples using account compression in the wild:

• Solana Program Library tests

• Metaplex Program Library Compressed NFT tests