Sign and send transaction (call contract function)

Question

I am using ethereumjs-accounts providerfor transaction signer in HookedWeb3Provider. And I am trying to call contract function which send tokens. It's my params for sign transaction.

let tx_params = {
        nonce: '00',
        gasPrice: '100',
        gasLimit: '100',
        from: account,
        to: contractParams.address,
        value: '00',
        data: '' //what should I place here to call contract function with arguments?
    };

then I am calling sign method:

signTransaction(tx_params, (err, hash)=>{})

and receiving hash

0xf86280820100832fefd894efcc9f9a5cb3d6062c18eeffdf90a29bb771fccc80801ba07c0226eb53fc4c8031a5346389fb17125b37ca96bec2ce5dd651808c8356ea9aa0aef5cb9e2a0426a6af2193a0fd9d3ec09f334614594faa54be17d9ddd64b72b1

A didn't understand how to send transaction with web3js and put there a signed transaction (or hash?)

this.web3.eth.sendRawTransaction(); 

Answer 1

In web3js Version 1.0.0

The data here should be the encoded ABI of the contract method you are trying to execute. See how to encode ABI definition of your contract method here.

For example: If your method call is buyItem('Pasta')

Then you would do something like this

var encodedABI = contractInstance.methods.buyItem(web3.utils.asciiToHex('Pasta')).encodeABI();
  var tx = {
    from: defaultAddress,
    to: contractInstance.options.address,
    gas: 2000000,
    data: encodedABI,
  };

Answer 2

With ethers.js v5:

1. create your smart contract instance

   const instance = new Contract(address, abi, signerOrProvider)

or just the interface

const interface = new ethers.utils.Interface(abi)

2. encode data

   const data = instance.interface.encodeFunctionData('yourFuncName', [inputParams])