Understanding Transaction Receipts


Transaction Receipts

Confirmed transactions come with a receipt under the result field when fetching the transaction in JSON format.

Basic Fields

The following are the fields a receipt may have. These fields generally apply to both payment and contract transactions.

FieldTypeDescription
cumulative_gasstringThe total gas consumed in this transaction
epoch_numstringThe epoch number in which this transaction was confirmed
successbooleanThe result of this transaction (true on success)

For example:

"receipt": {
"cumulative_gas": "10481",
"epoch_num": "586524",
"success": true
},

Additional Fields

For smart contract transactions, additional information relating to smart contract execution is contained in additional fields under the "receipt".

Successful Transactions

If a transaction is successful (i.e., the success field is true), these fields will be present:

FieldTypeDescription
acceptedbooleanIndicates whether the last transition in this transaction incurred a balance transfer
event_logsjson-arrayA list of event logs emitted by the contract during processing. Each log contains:
  1. _eventname: [string] The name of the event
  2. address: [string] The address of the contract that emitted this event
  3. params: [json-array] A list of parameters under the transition. Each entry contains:
    • vname: [string] The name of the variable
    • type: [string] The type of the variable
    • value: [string] The value of the variable
transitionsjson-arrayA list of internal transitions invoked during the processing of the transaction by the Scilla interpreter. Each transition contains:
  1. addr: [string] The address of the contract account that emitted this transition
  2. depth: [int] The depth of the current transition. The transitions directly emitted by the recipient in the transaction will be in depth 0. If those transitions in depth 0 invoked transitions from other contracts, those will be in depth 1. And so on and so forth.
  3. msg: [json-object] The message field emitted by the Scilla interpreter, which includes:
    • _amount: [string] The balance transferred from this transition
    • _recipient: [string] The recipient of this transition, which can either be a wallet account or contract account
    • _tag: [string] The contract-defined transition name
    • params: [json-array] A list of parameters under the transition. Each entry contains:
      • vname: [string] The name of the variable
      • type: [string] The type of the variable
      • value: [string] The value of the variable

For example:

"receipt": {
"accepted": true,
"cumulative_gas": "878",
"epoch_num": "589742",
"event_logs":[
{
"_eventname":"RecordsSet",
"address":"0x708bfbba57436ed45efc13df9fab4249a354e06b",
"params":[
{
"type":"ByStr20",
"value":"0x9611c53be6d1b32058b2747bdececed7e1216793",
"vname":"registry"
},
{
"type":"ByStr32",
"value":"0x2bb13c9b0a5dd28d42b470e2073df14608a9056310988b84b24dc342211e0627",
"vname":"node"
}
]
},
],
"success": true,
"transitions": [
{
"addr": "0x9a65df55b2668a0f9f5f749267cb351a37e1f3d9",
"depth": 0,
"msg": {
"_amount": "50000000000000",
"_recipient": "0xc0e28525e9d329156e16603b9c1b6e4a9c7ed813",
"_tag": "onFundsReceived",
"params": [
"vname": "emp_addr",
"type": "ByStr20",
"Value": "0x00345678901234567890123456789012345678ab"
]
}
}
]
}

Unsuccessful Transactions

If a transaction is unsuccessful (i.e., the success field is false), no balance transfer will be executed. Additionally, these fields will be present:

FieldTypeDescription
errorsjson-objectAn object containing a key-value field. The key [string] indicates the depth at which the error occurred. The value part is a JSON array that lists the error codes [int] reported. The list of possible error codes can be found here.
exceptionsjson-arrayA list of exceptions returned by the Scilla interpreter. Each exception contains:
  1. line”: [int] The line in the Scilla contract code where the exception was detected
  2. message: [string] The message describing the exception

For example:

"receipt": {
"cumulative_gas": "1220",
"epoch_num": "588004",
"errors": {
"0": [
7
]
},
"exceptions": [
{
"line": 87,
"message": "Exception thrown: (Message [(_exception : (String \"Error\")) ; (code : (Int32 -2))])"
},
{
"line": 100,
"message": "Raised from IsAdmin"
},
{
"line": 137,
"message": "Raised from ConfigureUsers"
}
],
"success": false
}

Recommended Steps for Exchanges Polling for Incoming $ZIL Deposit from Smart Contract Transactions

  1. Confirm that the success field is set to true.
  2. Traverse the transitions JSON array. For each transition, for a successful deposit of $ZIL via the smart contract, the following must be fulfilled:
    1. _recipient corresponds to a known deposit address controlled by the exchange.
    2. _tag is either AddFunds or empty.
      note

      _tag can be found under msg field. If either _tag or msg is not present, there is no incoming deposit from this particular transition.

    3. _amount is non-zero.
    4. Check the _recipient and _amount to complete the information on the balance transfer. In such a case, you can confirm that there is a deposit to address _recipient with value _amount (in Qa).
    5. Continue traversing the remaining transitions and checking for more deposits.