Simulate

Simulate transaction

The output of the transaction will have the exact transaction outputs and events that running an actual signed transaction would have. However, it will not have the associated state hashes, as they are not updated in storage. This can be used to estimate the maximum gas units for a submitted transaction.

To use this, you must:

• Create a SignedTransaction with a zero-padded signature.
• Submit a SubmitTransactionRequest containing a UserTransactionRequest containing that signature.

To use this endpoint with BCS, you must submit a SignedTransaction encoded as BCS. See SignedTransaction in types/src/transaction/mod.rs.

POSThttps://apt.nownodes.io/v1/transactions/simulate

Query parameters

Body

application/jsonapplication/x.aptos.signed_transaction+bcs

sender*Address (string (hex))

A hex encoded 32 byte Aptos account address.

This is represented in a string as a 64 character hex string, sometimes shortened by stripping leading 0s, and adding a 0x.

For example, address 0x0000000000000000000000000000000000000000000000000000000000000001 is represented as 0x1.

Example: "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 "

sequence_number*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

max_gas_amount*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

gas_unit_price*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

expiration_timestamp_secs*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

payload*TransactionPayload (object)

An enum of the possible transaction payloads

TransactionPayload_EntryFunctionPayload (all of)TransactionPayload_ScriptPayload (all of)TransactionPayload_ModuleBundlePayload (all of)TransactionPayload_MultisigPayload (all of)

signature*TransactionSignature (object)

An enum representing the different transaction signatures available

TransactionSignature_Ed25519Signature (all of)TransactionSignature_MultiEd25519Signature (all of)TransactionSignature_MultiAgentSignature (all of)TransactionSignature_FeePayerSignature (all of)TransactionSignature_AccountSignature (all of)

Response

200400403404413500503507

Headers

Body

application/jsonapplication/x-bcs

version*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

hash*HashValue (string)

state_change_hash*HashValue (string)

event_root_hash*HashValue (string)

state_checkpoint_hashHashValue (string)

gas_used*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

success*boolean

Whether the transaction was successful

vm_status*string

The VM status of the transaction, can tell useful information in a failure

accumulator_root_hash*HashValue (string)

changes*array of WriteSetChange (object)

Final state of resources changed by the transaction

sender*Address (string (hex))

A hex encoded 32 byte Aptos account address.

This is represented in a string as a 64 character hex string, sometimes shortened by stripping leading 0s, and adding a 0x.

For example, address 0x0000000000000000000000000000000000000000000000000000000000000001 is represented as 0x1.

Example: "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 "

sequence_number*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

max_gas_amount*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

gas_unit_price*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

expiration_timestamp_secs*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

payload*TransactionPayload (object)

An enum of the possible transaction payloads

TransactionPayload_EntryFunctionPayload (all of)TransactionPayload_ScriptPayload (all of)TransactionPayload_ModuleBundlePayload (all of)TransactionPayload_MultisigPayload (all of)

signatureTransactionSignature (object)

An enum representing the different transaction signatures available

TransactionSignature_Ed25519Signature (all of)TransactionSignature_MultiEd25519Signature (all of)TransactionSignature_MultiAgentSignature (all of)TransactionSignature_FeePayerSignature (all of)TransactionSignature_AccountSignature (all of)

events*array of Event (object)

Events generated by the transaction

timestamp*U64 (string (uint64))

A string containing a 64-bit unsigned integer.

We represent u64 values as a string to ensure compatibility with languages such as JavaScript that do not parse u64s in JSON natively.

Example: "32425224034"

Request

JavaScriptCurlPython

const response = await fetch('https://apt.nownodes.io/v1/transactions/simulate', {
    method: 'POST',
    headers: {
      "Content-Type": "application/json"
    },
    body: JSON.stringify({
      "sender": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 ",
      "sequence_number": "32425224034",
      "max_gas_amount": "32425224034",
      "gas_unit_price": "32425224034",
      "expiration_timestamp_secs": "32425224034",
      "payload": {
        "type": "entry_function_payload",
        "function": "0x1::aptos_coin::transfer",
        "type_arguments": [
          "text"
        ],
        "arguments": []
      },
      "signature": {
        "type": "ed25519_signature",
        "public_key": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 ",
        "signature": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 "
      }
    }),
});
const data = await response.json();

Response

200400403404413500503507

[
  {
    "version": "32425224034",
    "hash": "text",
    "state_change_hash": "text",
    "event_root_hash": "text",
    "state_checkpoint_hash": "text",
    "gas_used": "32425224034",
    "success": false,
    "vm_status": "text",
    "accumulator_root_hash": "text",
    "changes": [
      {
        "type": "delete_module",
        "address": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 ",
        "state_key_hash": "text",
        "module": "0x1::aptos_coin"
      }
    ],
    "sender": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 ",
    "sequence_number": "32425224034",
    "max_gas_amount": "32425224034",
    "gas_unit_price": "32425224034",
    "expiration_timestamp_secs": "32425224034",
    "payload": {
      "type": "entry_function_payload",
      "function": "0x1::aptos_coin::transfer",
      "type_arguments": [
        "text"
      ],
      "arguments": []
    },
    "signature": {
      "type": "ed25519_signature",
      "public_key": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 ",
      "signature": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 "
    },
    "events": [
      {
        "guid": {
          "creation_number": "32425224034",
          "account_address": "0x88fbd33f54e1126269769780feb24480428179f552e2313fbe571b72e62a1ca1 "
        },
        "sequence_number": "32425224034",
        "type": "text"
      }
    ],
    "timestamp": "32425224034"
  }
]