How can I set the gas price while deploying a contract with web3.js?

Question

I set up a Geth node on the Rinkeby network recently. And while I can send ordinary transactions in seconds without a problem, I can't seem to get a contract creation to happen in less than an hour. When I compile a simple contract in Remix and then paste the web3.js deployment code it generates into the Geth console--it submits the transaction onto the network, but then it just sits there for over an hour without any of the authorized nodes ever accepting it into a block. Although eventually it gets accepted.

I am wondering if the issue here may be the gas price. Based on etherscan, it looks like web3.js decided to set the gas price for the transaction to 4 gwei. I have verified that the average for the network is currently only 2 gwei, but still--I'd like to eliminate this as a possibility. (The gas limit is definitely not a problem--set to 4700000 and the estimated gas for the contract creation code according to Remix is only 80924.)

If anyone reads this and suspects what I'm seeing is due to something other than the gas price being too low, then feel free to view the transaction here and make suggestions:

https://rinkeby.etherscan.io/tx/0xe134c193cead33031e3348ebb1db42115fdf156cb5e1a1d43d5c4ecfdf026413

Anyway, my specific question is: where is this default gas price of 4gwei coming from, and how can I override it with something higher?

For some reason in the documentation for web3.js there is no mention of any way to specify the gas price for a contract creation, even though it does provide a way to specify it for an ordinary transaction:

https://github.com/ethereum/wiki/wiki/JavaScript-API

Can I just pass an additional option to web3.eth.contract() of gasPrice= , or perhaps to myContract.new()?

Answer 1

From the documentation:

var contractInstance = MyContract.new([constructorParam1] [, constructorParam2],
  {data: '0x12345...', from: myAccount, gas: 1000000});

Yes, you can just add a gasPrice to that object:

var contractInstance = MyContract.new([constructorParam1] [, constructorParam2],
 {data: '0x12345...', from: myAccount, gas: 1000000, gasPrice: web3.toWei(2, 'gwei')});

Answer 2

web3 also has a function to estimate the gas needed, you could do something like:

var gasEstimate = web3.eth.estimateGas({data: bytecode});
var contract = web3.eth.contract(abi);
var instance = contract.new({data: bytecode, from: from, gas: gasEstimate});
var receipt = web3.eth.getTransactionReceipt(instance.transactionHash);

Answer 3

You can override the gas price in your code, like below.

    const tx = {
      from: walletAddress,
      to: contractAddress,
      gas: 4700000,
      gasPrice: 20000000000,
      data: encodedABI,
    };

Where you can use the tx variable like below (I skipped the part where you need to instantiate your HttpProvider)

....
...
smartContract = new web3.eth.Contract(abi, contractAddress);

const privateKey = '0x' + '12714D.....A3D8CC53';
const walletAddress = '0x77.....60';

// change this to whatever contract method you are trying to call, e.g. buyToken(type, title, desc)
const query = smartContract.methods.buyToken(type, title, desc);
const encodedABI = query.encodeABI();
const tx = {
  from: walletAddress,
  to: contractAddress,
  gas: 4700000,
  gasPrice: 10,
  data: encodedABI,
};

const account = web3.eth.accounts.privateKeyToAccount(privateKey);
console.log(account);
web3.eth.getBalance(walletAddress).then(console.log);

web3.eth.accounts.signTransaction(tx, privateKey).then(signed => {
  const tran = web3.eth
    .sendSignedTransaction(signed.rawTransaction)
    .on('confirmation', (confirmationNumber, receipt) => {
      console.log('=> confirmation: ' + confirmationNumber);
    })
    .on('transactionHash', hash => {
      console.log('=> hash');
      console.log(hash);

    })
    .on('receipt', receipt => {
      console.log('=> reciept');
      console.log(receipt);
    })
    .on('error', console.error);
});

Your transaction fee would be gas used x gasPrice. How to know gas used? You can only know after it's been used like viewing your transaction receipt, see image below (under transaction cost item in Remix where it shows 206993 gas).

P/S: I'M STILL A NEWBIE IN ETHEREUM AND JUST WANTING TO HELP. IF I MADE ANY ERROR PLEASE DONT DOWNVOTE BUT LEAVE COMMENTS AND I SHALL EDIT MY ANSWER