Calling ethereum smart contracts with value using web3js and galanche

Question

I'm fairly new to Ethereum smart contracts, so this might be a stupid question, but I need someone to help me out. I've set up Galanche on my machine (MacOS 11) and written a very simple currency smart contract (I don't intend to use it as an actual currency, I just want to learn about smart contracts) using truffle.

I've compiled the contract and deployed it to my Galanche blockchain successfully.

Now, I want to interact with it using web3.js. I have set up a nodejs project and installed web3. As a first test, I ran the following script:

const Web3 = require("web3");
const fs = require("fs");

const web3 = new Web3("http://192.168.178.49:7545");
const abi = JSON.parse(
  fs.readFileSync("path/to/compiled/MyCoin.json").toString()
).abi;

const MyCoin = new web3.eth.Contract(
  abi,
  // My contract's address
  "0x3265aA0A2c3ac15D0eDd67BC0fa62A446c112F98"
);

(async () => {
  console.log("Starting!");
  var coinCount = await MyCoin.methods
    .getTotalCoins()
    .call({ from: "0x2d0616BF48214513f70236D59000F1b4f395a2Fd" });
  console.log("Current registered MyCoin tokens:", coinCount);
})();

The address 0x2d0616BF48214513f70236D59000F1b4f395a2Fd is the first address displayed to me in Galanche

It works as expected and returns the default amount of coins.

Now, I want to run a method called buyMyCoin which requires a payment. I tried running:

...

MyCoin
  .methods
  .buyMyCoin
  .send(
    {
      from: '0x2d0616BF48214513f70236D59000F1b4f395a2Fd',
      value: some_amount_of_wei
    }
  );

...

I'd expect that when I run this node.js script again, the first part would tell me that there are <n> total coins, but it doesn't. It just returns the same value as the last time.

Am I doing something wrong with web3.js or is this an issue with my contract?

BTW: I didn't see any funds leave the address 0x2d0616BF48214513f70236D59000F1b4f395a2Fd in Galanche, so I'm pretty sure it's not my contract...

I expect that somewhere I'd have to sign into this address using its public key, but I can't find anything about that in the web3.js docs that isn't very ambiguous...

Edit: Here's the code for my buyMyCoin method:

...
  /**
   * @dev Buy MyCoin
   */
  function buyMyCoin() external payable {
    require(msg.value > 1 gwei, "Minimum transaction is 1 gwei"); // Not very much

    uint256 amount = convert(msg.value, conversionRate, true);

    balances[msg.sender].owner = payable(msg.sender);
    balances[msg.sender].amount += amount;

    totalCoins += amount;
  }
...

Please edit your question and show the Solidity buyMyCoin() function and its dependencies. There might be a requirement in the code (my guess is missing payable modifier or failing require()) that causes the transaction to revert... And btw, it's Ganache, not Galanche :) — Petr Hejda
@PetrHejda Yes, there is a requirement that requires the transaction value to be greater than 1 gwei... Is there a way to detect a failing requirement? BTW: The error event doesn't seem to be triggering either... — Jake

Jake Jake · Accepted Answer · 2021-04-28T21:43:07

turns out it was just me being stupid! I was trying to run the transaction with an outrageously low amount of ether (4 gwei) which is, of course, so small that it can't be seen in the Ganache app.

The reason I was seeing no new coins being created was because my conversion code rounded the result to 0.

Calling ethereum smart contracts with value using web3js and galanche

1 Answers