Built-In Functions

Introduction

MultiversX protocol has a set of built-in functions. A built-in function is a special protocol-side function that doesn't require a specific smart contract address as receiver of the transaction. When such a function is called via a transaction, built-in handlers are triggered and will execute it.

Calls to these functions are considered built-in function calls and are treated different than other smart contract calls.

This documentation is subject to change, but at the time of writing, the current built-in functions were:

• ClaimDeveloperRewards
• ChangeOwnerAddress
• SetUserName
• SaveKeyValue
• ESDTTransfer
• ESDTBurn
• ESDTFreeze
• ESDTUnFreeze
• ESDTWipe
• ESDTPause
• ESDTUnPause
• ESDTSetRole
• ESDTUnSetRole
• ESDTSetLimitedTransfer
• ESDTUnSetLimitedTransfer
• ESDTLocalBurn
• ESDTLocalMint
• ESDTNFTTransfer
• ESDTNFTCreate
• ESDTNFTAddQuantity
• ESDTNFTBurn
• ESDTNFTAddURI
• ESDTNFTUpdateAttributes
• MultiESDTNFTTransfer
• SetGuardian
• GuardAccount
• UnGuardAccount

ClaimDeveloperRewards

This function is to be used by Smart Contract owners in order to claim the fees accumulated during smart contract calls. Currently, the developer reward is set to 30% of the fee of each smart contract call.

ClaimDeveloperRewardsTransaction {
    Sender: <the owner of the SC>
    Receiver: <SC address>
    Value: 0
    GasLimit: 6_000_000
    Data: "ClaimDeveloperRewards"
}

For more details about how arguments have to be encoded, check here.

note

The amount of available developer rewards can be viewed via Get Address endpoint when using the smart contract as the bech32Address.

ChangeOwnerAddress

ChangeOwnerAddress is the function to be called by a Smart Contract's owner when a new owner is desired.

ChangeOwnerAddressTransaction {
    Sender: <the current owner of the SC>
    Receiver: <SC address>
    Value: 0
    GasLimit: 6_000_000
    Data: "ChangeOwnerAddress" +
          "@" + <new owner address in hexadecimal encoding>
}

For more details about how arguments have to be encoded, check here.

SetUserName

SetUserName is used to set an username for a given address. The receiver's address has to be the DNS smart contract address of the address.

SetUserNameTransaction {
    Sender: <sender>
    Receiver: <DNS address that corresponds to the sender>
    Value: 0
    GasLimit: 1_200_000
    Data: "SetUserName" +
          "@" + <username in hexadecimal encoding>
}

For more details about how arguments have to be encoded, check here.

SaveKeyValue

SaveKeyValue is used to store a given key-value under an address's storage. More details and the transaction's format are already covered here.

ESDT and NFT built-in functions

Most of the ESDT and NFT related built-in function are already described in the ESDT and NFT sections.

SetGuardian

SetGuardian is used to set a guardian for a given address.

SetGuardianTransaction {
    Sender: <sender address>
    Receiver: <sender address>
    Value: 0
    GasLimit: 1_000_000
    Data: "SetGuardian" +
          "@" + <guardian address in hexadecimal encoding> +
          "@" + <service ID in hexadecimal encoding>
}

For more details about how arguments have to be encoded, check here.

note

1. After sending a SetGuardian transaction, the user has to wait for 20 epochs until the chosen guardian becomes activeGuardian (activationEpoch field will show the epoch when a pendingGuardian will become active). Until the activationEpoch is reached, the chosen guardian will be seen as pendingGuardian. See Guardian Data for more information.
2. In the case an address already has an activeGuardian, and the user wants to change it, a SetGuardian transaction has to be sent again and 20 epochs have to be awaited.
3. If the account is already Guarded (see below GuardAccount transaction), a user can Fast SetGuardian (not waiting for the 20 epochs anymore) by sending a guarded transaction.

GuardAccount

GuardAccount is used to guard the account. In other words, after sending this transaction (and if it is successfull), all transactions that will be sent afterwards by this address must have guardian and guardianSignature filled in until a successfull UnGuardAccount transaction is being sent.

GuardAccountTransaction {
    Sender: <sender address>
    Receiver: <sender address>
    Value: 0
    GasLimit: 1_000_000
    Data: "GuardAccount"
}

For more details about how arguments have to be encoded, check here.

note

After sending a successfull GuardAccount transaction, only co-signed (guarded) transactions can be sent. Any other transaction will not be processed, except a new SetGuardian (for which 20 epochs must pass until the changes will occur).

UnGuardAccount

UnGuardAccount is used to unguard the account. After a successfull transaction, it is not mandatory anymore for the user to send co-signed (guarded) transactions.

UnGuardAccountTransaction {
    Nonce: <>
    Sender: <sender address>
    Receiver: <sender address>
    Guardian: <guardian address>
    Value: 0
    GasLimit: 1_000_000
    Data: "UnGuardAccount"
    Signature: <sender signed transaction>
    GuardianSignature: <guardian signed transaction>
    Version: 2
    Options: <the second least significant bit should be 1 (example: 02, or 03)>
}

note

Please be aware that the UnGuardAccount operation can only be performed through a guarded transaction when you have access to your activated guardian. Otherwise, you will need to change the guardian (and wait the 20 epochs) prior to performing the unguarding process.

For more details about how arguments have to be encoded, check here.