triggerconstantcontract¶

Read-only contract call (does not go on-chain). Used to read view/pure functions or simulate transactions.

Source: framework/src/main/java/org/tron/core/services/http/TriggerConstantContractServlet.java
Method: POST
Contract: protocol.TriggerSmartContract
Response: api.TransactionExtention
Solidity endpoint: /walletsolidity/triggerconstantcontract

Request parameters¶

Field	Type	Required	Description
`owner_address`	string	Yes	Caller address (`msg.sender` in the contract)
`contract_address`	string	Yes	Target contract address
`function_selector`	string	No	Function signature
`parameter`	string	No	ABI-encoded parameters (hex)
`data`	string	No	Call data (hex); use either this or `function_selector`
`call_value`	int64	No	TRX (sun) sent with the call
`token_id`	int64	No	TRC10 token id sent with the call
`call_token_value`	int64	No	TRC10 amount sent with the call
`extra_data`	string	No	Transaction memo (hex; UTF-8 text when `visible=true`)
`permission_id`	int32	No	Multi-sig permission ID
`visible`	bool	No	Format for addresses and text fields (response includes `result.message`, which is affected by `visible`)

Example:

curl --request POST \
     --url https://nile.trongrid.io/wallet/triggerconstantcontract \
     --header 'accept: application/json' \
     --header 'content-type: application/json' \
     --data '
{
  "owner_address":    "41dd791d6b49e190062d650e6a23c575510d35f2f9",
  "contract_address": "41eca9bc828a3005b9a3b909f2cc5c2a54794de05f",
  "function_selector": "balanceOf(address)",
  "parameter":         "000000000000000000000000dd791d6b49e190062d650e6a23c575510d35f2f9"
}
'

Response¶

TransactionExtention:

Field	Type	Description
`transaction`	Transaction	Unsigned transaction (context only — should not be signed and broadcast)
`txid`	string(hex)	Transaction hash
`constant_result`	repeated bytes(hex)	ABI-encoded hex of the function return value; on revert, this is the ABI-encoded revert reason (the leading 4 bytes `08c379a0` are the `Error(string)` selector)
`result`	Return	Status; on revert / failed `require`, `result.result=false` and `result.message` contains `REVERT opcode executed` or `runtime error`
`energy_used`	int64	Estimated energy consumed
`energy_penalty`	int64	Energy penalty (if any)
`logs`	repeated TransactionLog	Event logs (if emitted)
`internal_transactions`	repeated InternalTransaction	Internal calls (if any)

Response example (real Nile capture):

{
  "result": { "result": true },
  "energy_used": 935,
  "constant_result": ["0000000000000000000000000000000000000000000000000000000040cfcc00"],
  "transaction": {
    "ret": [{}],
    "visible": false,
    "txID": "cff6488e738ce77f7325572fe0aa2470f87dbf1c95eeeb2c25feec59d5afa35c",
    "raw_data": {
      "contract": [
        {
          "parameter": {
            "value": {
              "data":             "70a08231000000000000000000000000dd791d6b49e190062d650e6a23c575510d35f2f9",
              "owner_address":    "41dd791d6b49e190062d650e6a23c575510d35f2f9",
              "contract_address": "41eca9bc828a3005b9a3b909f2cc5c2a54794de05f"
            },
            "type_url": "type.googleapis.com/protocol.TriggerSmartContract"
          },
          "type": "TriggerSmartContract"
        }
      ],
      "ref_block_bytes": "28c0",
      "ref_block_hash":  "9eabbe133123b34c",
      "expiration":      1777447218000,
      "timestamp":       1777447160779
    },
    "raw_data_hex": "0a0228c022089eabbe133123b34c40d0d6f0c0dd335a8e01081f1289010a31747970652e676f6f676c65617069732e636f6d2f70726f746f636f6c2e54726967676572536d617274436f6e747261637412540a1541dd791d6b49e190062d650e6a23c575510d35f2f9121541eca9bc828a3005b9a3b909f2cc5c2a54794de05f222470a08231000000000000000000000000dd791d6b49e190062d650e6a23c575510d35f2f970cb97edc0dd33"
  }
}

txID / ref_block_* / expiration / timestamp / raw_data_hex and other ephemeral fields share semantics with /wallet/createtransaction. Constant calls do not go on-chain; the transaction field is provided only as context.

Error responses¶

This endpoint never writes {"Error": ...}. All exceptions are caught and written into result.code / result.message; the HTTP body is still a TransactionExtention. Note: EVM revert / runtime errors do not go through result.code — instead result.result=true, message carries the revert/runtime info, and the failure is marked at transaction.ret[0].ret="FAILED".

Trigger	`result.result`	`result.code`	`result.message`	Other
Contract does not exist / validation failed (`ContractValidateException`)	default (false)	`CONTRACT_VALIDATE_ERROR`	Original validator message	—
EVM revert / failed `require`	true	default (`SUCCESS`, omitted)	`REVERT opcode executed`	`transaction.ret[0].ret="FAILED"`; `constant_result[0]` is the `Error(string)` ABI encoding (when the contract supplies a reason)
EVM runtime error (OOG, illegal opcode, etc., no `result.getException()`)	true	default (`SUCCESS`, omitted)	Raw `result.getRuntimeError()` string	Same as above
`result.getException() != null` (e.g. `OutOfTimeException`)	default (false)	`OTHER_ERROR`	`<exceptionClass> : <message>` (`"` → `'`)	—
Other (hex parsing, missing parameters, proto merge, etc.)	default (false)	`OTHER_ERROR`	`<exceptionClass> : <message>` (`"` → `'`)	—

On revert, result.message does not carry the original reason string; you must decode it from constant_result[0]: skip the leading 4-byte 08c379a0 selector and ABI-decode the remaining bytes as string.