# TriggerConstantContract
Invoke the readonly function (modified by the `view` or `pure` modifier) of a contract for contract data query; or Invoke the non-readonly function of a contract for predicting whether the transaction can be successfully executed and estimating the energy consumption; or estimate the energy consumption of contract deployment.
This method will use `30` [Compute Units](/v1/about/billing.md).
***
**Note:**
* TriggerConstantContract operation will not generate an on-chain transaction, nor will it change the status of the current node.
* For estimating energy
* To estimate the energy consumption of contract deployment just by passing the bytecode of contract through the `data` field
* To estimate energy consumption of Contract Calls by calling non-read-only methods of contracts
* When using triggerconstantcontract to estimate energy consumption, the `energy_used` field in the returned value is the energy consumption. Therefore, the `fee_limit` of the transaction can be set to `energy_used x energy unit price`.
* Parameter encoding and decoding example: [Parameter and return value encoding and decoding](https://developers.tron.network/docs/parameter-and-return-value-encoding-and-decoding)
## **Parameters**
* `owner_address` - String - Owner address that triggers the contract. If visible=true, use base58check format, otherwise use hex format. For constant call you can use the all-zero address.
* `contract_address` - String - Smart contract address. If visible=true, use base58check format, otherwise use hex format
* `function_selector` - String - Function call, must not be left blank
* `parameter` - String - Parameter encoding needs to be in accordance with the ABI rules, the rules are more complicated, users can use the ethers library to encode,For details, please refer to the document-Guide-Smart Contract-Best Practice-Parameter Encoding and Decoding.
* `data` - String - The data for interacting with smart contracts, including the contract function and parameters. You can choose to use this field, or you can choose to use function\_selector and parameter for contract interaction. When both of data and function\_selector exist, function\_selector is preferred
* `call_value` - int64 - Amount of TRX transferred to the contract with this transaction, the unit is sun. This field may be used when estimating energy consumption
* `call_token_value` - int64 - Amount of TRC10 token transferred with this transaction
* `token_id` - int64 - TRC10 token id
* `visible` - boolean - Optional. Specifies whether the address is in Base58 format (default: false)
## **Returns**
| Field | Type | Description |
| ---------------- | ----------- | ---------------------------------------------------------------------------------------------------------------------------------- |
| result | Return | Run result, for detailed parameter definition, refer to [EstimateEnergy](https://developers.tron.network/reference/estimateenergy) |
| energy\_used | int64 | Estimated energy consumption, including the basic energy consumption and penalty energy consumption |
| energy\_penalty | int64 | The penalty energy consumption |
| constant\_result | string\[] | Result list |
| transaction | Transaction | Transaction information, refer to [GetTransactionByID](https://developers.tron.network/reference/wallet-gettransactionbyid) |
```json
// Result
{
"result": {
"result": true
},
"energy_used": 541,
"constant_result": [
"00000000000000000000000000000000000000000000000000000001a2127a5b"
],
"transaction": {
"ret": [
{}
],
"visible": true,
"txID": "34c6bae6cc31b8e8d1ee72a73a35125e157907bf2a294f4159b0fd087e68a21d",
"raw_data": {
"contract": [
{
"parameter": {
"value": {
"data": "70a08231000000000000000000000000a614f803b6fd780986a42c78ec9c7f77e6ded13c",
"owner_address": "TZ4UXDV5ZhNW7fb2AMSbgfAEZ7hWsnYS2g",
"contract_address": "TG3XXyExBkPp9nzdajDZsozEu4BkaSJozs"
},
"type_url": "type.googleapis.com/protocol.TriggerSmartContract"
},
"type": "TriggerSmartContract"
}
],
"ref_block_bytes": "538e",
"ref_block_hash": "9351f61b61513758",
"expiration": 1757411406000,
"timestamp": 1757411347066
},
"raw_data_hex": "0a02538e22089351f61b6151375840b0e187ef92335a8e01081f1289010a31747970652e676f6f676c65617069732e636f6d2f70726f746f636f6c2e54726967676572536d617274436f6e747261637412540a1541fd49eda0f23ff7ec1d03b52c3a45991c24cd440e12154142a1e39aefa49290f2b3f9ed688d7cecf86cd6e0222470a08231000000000000000000000000a614f803b6fd780986a42c78ec9c7f77e6ded13c70fa9484ef9233"
}
}
```
{% tabs %}
{% tab title="mainnet" %}
```bash
curl https://mainnet.tron.validationcloud.io/v1//wallet/triggerconstantcontract \
-X POST \
-H "Content-Type: application/json" \
-d '
{
"owner_address": "TZ4UXDV5ZhNW7fb2AMSbgfAEZ7hWsnYS2g",
"contract_address": "TG3XXyExBkPp9nzdajDZsozEu4BkaSJozs",
"function_selector": "balanceOf(address)",
"parameter": "000000000000000000000000a614f803b6fd780986a42c78ec9c7f77e6ded13c",
"visible": true
}
'
```
{% endtab %}
{% endtabs %}
---
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