How to send messages on a transaction in the Ethereum

Question

I want to send a message on a transaction. Here is my codes:

_data = web3.toHex('xxxx');

instance.function_name(param1, param2, param3, param4, {value: web3.toWei(_price, 'ether'), from: web3.eth.accounts[0], data:_data}).then(...);

The transaction is processed successfully, But the input data message is not the _data value in the etherscan.io

can anybody help me? Thank you.

Answer 1

The data field in the transaction object is used when deploying a contract or when using the general sendTransaction or sendRawTransaction methods. If you are using a contract instance, the data field is ignored.

From the Solidity docs :

Object - (optional) The (previous) last parameter can be a transaction object, see web3.eth.sendTransaction parameter 1 for more. Note: data and to properties will not be taken into account.

If you want to send the data manually, use sendTransaction .

The information shown in Etherscan is the decoded data from the signed transaction describing the function call made. It is not free form user data (if that's what you're trying to insert). The first 32 bits of the data are the function signature and each 256 bit block afterwards are the parameters.

See this source for more in-depth information.