Create a HookStore Transaction

The HookStoreTransaction enables efficient, low-overhead management of an EVM Hook’s persistent storage. This transaction allows hook owners to add, update, or remove key/value pairs in the hook’s storage without executing the hook’s bytecode—significantly more cost-effective and faster than using a ContractCall.

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Transaction Properties

Field	Description
Hook ID	The unique identifier of the EVM Hook whose storage is being updated, including the owning entity (Account or Contract) and the hook’s 64-bit ID.
Storage Updates	A list of updates to the hook’s persistent storage. Supports direct slot updates (EvmHookStorageSlot) or Solidity mapping updates (EvmHookMappingEntries).

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When to Use This Transaction

Use HookStoreTransaction when you need to:

• Initialize storage slots on a newly created hook
• Update configuration variables (e.g., whitelist, passcode hash) in an existing hook’s storage
• Delete storage entries by setting their value to an empty byte array

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Transaction Signing Requirements

The signing requirements depend on if an adminKey was set when the hook was created:

• If the hook has an adminKey: Either the Admin Key OR the hook owner (account or contract that owns the hook) must sign the transaction
• If the hook does NOT have an adminKey: The hook owner (account or contract that owns the hook) must sign the transaction
• In all cases: The account paying the transaction fee must also sign

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Methods

Method	Type	Description
setHookId(<HookId>)	HookId	Required. Sets the unique identifier of the EVM Hook whose storage is being updated.
addStorageUpdate(<update>)	EvmHookStorageUpdate	Optional. Adds a single storage update (slot or mapping entry) to the transaction.
setStorageUpdates(<updates>)	list<EvmHookStorageUpdate>	Optional. Sets the full list of storage updates for the transaction.
getHookId()	HookId	Returns the hook ID for this transaction. In JavaScript, use the .hookId property accessor instead of calling getHookId().
getStorageUpdates()	list<EvmHookStorageUpdate>	Returns the list of storage updates. In JavaScript, use the .storageUpdates property accessor instead of calling getStorageUpdates().

EvmHookStorageUpdate is an abstract class with two concrete implementations: EvmHookStorageSlot for direct slot updates and EvmHookMappingEntries for updating entries within a Solidity mapping. See Create and Manage Hooks for full property details on both types.

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Examples

Example 1: Updating a Hook’s Storage Slot

This example demonstrates how to update a single storage slot on a hook with ID 1002 owned by accountId.

Java

import com.hedera.hashgraph.sdk.HookStoreTransaction;
import com.hedera.hashgraph.sdk.HookId;
import com.hedera.hashgraph.sdk.HookEntityId;
import com.hedera.hashgraph.sdk.EvmHookStorageUpdate;

// Assume these variables are defined:
// AccountId accountId = AccountId.fromString("0.0.1000");
// PrivateKey adminKey = PrivateKey.fromString("..."); // The hook's admin key

// 1. Define the target hook ID
HookId hookIdObj = new HookId(new HookEntityId(accountId), 1002L);

// 2. Define the new storage update (slot 0x01 → value 0x02)
byte[] key = new byte[32];
key[0] = 0x01;
byte[] value = new byte[32];
value[0] = 0x02;

EvmHookStorageUpdate.EvmHookStorageSlot storageUpdate =
    new EvmHookStorageUpdate.EvmHookStorageSlot(key, value);

// 3. Create and execute the HookStoreTransaction
HookStoreTransaction hookStoreTx = new HookStoreTransaction()
    .setHookId(hookIdObj)
    .addStorageUpdate(storageUpdate)
    .freezeWith(client)
    .sign(adminKey); // Must be signed by the hook's admin key

TransactionResponse result = hookStoreTx.execute(client);
System.out.println("HookStoreTransaction executed with ID: " + result.transactionId);

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Example 2: Updating a Solidity Mapping Entry

This example demonstrates how to update an entry within a Solidity mapping stored in the hook’s storage. This requires calculating the storage slot key based on the mapping key and the mapping’s storage slot.

Java

import com.hedera.hashgraph.sdk.HookStoreTransaction;
import com.hedera.hashgraph.sdk.HookId;
import com.hedera.hashgraph.sdk.HookEntityId;
import com.hedera.hashgraph.sdk.EvmHookStorageUpdate;
import com.hedera.hashgraph.sdk.EvmHookMappingEntry;
import java.util.List;

// Assume these variables are defined:
// AccountId accountId = AccountId.fromString("0.0.1000");
// PrivateKey adminKey = PrivateKey.fromString("..."); // The hook's admin key

// 1. Define the target hook ID
HookId hookIdObj = new HookId(new HookEntityId(accountId), 1002L);

// 2. Define the mapping update
// We are updating a mapping at Solidity storage slot 0x02.
// The mapping key is an address (0x...1234) and the new value is a boolean (true).

// Mapping Key (e.g., an address)
byte[] mappingKey = new byte[32];
mappingKey[31] = 0x34;
mappingKey[30] = 0x12;

// Mapping Slot (Solidity slot 2)
byte[] mappingSlot = new byte[32];
mappingSlot[31] = 0x02;

// New Value (e.g., a boolean 'true' which is 1)
byte[] newValue = new byte[32];
newValue[31] = 0x01;

// Create the mapping entry
EvmHookMappingEntry mappingEntry = EvmHookMappingEntry.ofKey(mappingKey, newValue);

// Create the mapping update
EvmHookStorageUpdate.EvmHookMappingEntries storageUpdate =
    new EvmHookStorageUpdate.EvmHookMappingEntries(
        mappingSlot,
        List.of(mappingEntry)
    );

// 3. Create and execute the HookStoreTransaction
HookStoreTransaction hookStoreTx = new HookStoreTransaction()
    .setHookId(hookIdObj)
    .addStorageUpdate(storageUpdate)
    .freezeWith(client)
    .sign(adminKey); // Must be signed by the hook's admin key

TransactionResponse result = hookStoreTx.execute(client);
System.out.println("HookStoreTransaction executed with ID: " + result.transactionId);