[Ethereum] Cannot send funds to a smart contract using web3j

web3j

I'm trying to send funds to a smart contract using the following code, however, the balance is always 0.

TransactionReceipt transactionReceipt = Transfer.sendFunds(
            web3j, credentials, recipient,
            amount, Convert.Unit.WEI)
            .sendAsync().get();
EthGetBalance contractGetBalance = web3j.ethGetBalance(recipient, DefaultBlockParameterName.LATEST)
              .sendAsync().get();
    BigInteger contractBalance = contractGetBalance.getBalance();

Why doesn't it go through? The smart contract code is:

pragma solidity ^0.4.7;

contract ReceiveContract {
  address public owner;

  function ReceiveContract() public {
    owner = msg.sender;
  }

  function () payable public {
    owner.transfer(msg.value);
  }

}

Best Answer

So I found a solution, and it was to change my send code to use raw transactions

    EthGetTransactionCount ethGetTransactionCount = web3j.ethGetTransactionCount(
            credentials.getAddress(), DefaultBlockParameterName.LATEST).sendAsync().get();
    BigInteger nonce = ethGetTransactionCount.getTransactionCount();
    RawTransaction rawTransaction  = RawTransaction.createEtherTransaction(
             nonce, ManagedTransaction.GAS_PRICE, Contract.GAS_LIMIT, recipient, amount);
    byte[] signedMessage = TransactionEncoder.signMessage(rawTransaction, credentials);
    String hexValue = Numeric.toHexString(signedMessage);
    EthSendTransaction ethSendTransaction = web3j.ethSendRawTransaction(hexValue).sendAsync().get();

Related Solutions

Web3j – Error Processing Transaction: Sender Doesn’t Have Enough Funds

There is different way to send transactions to a smart contract through node:

(1) A client signs a transaction with his account (private key) and send it to the node. Then the node only broadcasts it to the network. Transaction fees are paid by the client.
(2) A client sends a clear transaction (no signature) and ask the node to sign and broadcast the transaction with one of the account managed by this node. That's the all concept of personal unlocked account which should be used only for personal use or testing. Transaction fees are paid by the node.

By doing this (below), you basically create an account directly on the node (2)

NewAccountIdentifier newAccountIdentifier = admin.personalNewAccount(key).send();
String address = newAccountIdentifier.getAccountId();

If you want to create and manage an account only on the client (java program), you would have to do this:

ECKeyPair keyPair = Keys.createEcKeyPair(); 
Credentials credentials = Credentials.create(privateKey);

In web3j you have the concept of TransactionManager responsible of executing the transactions and you have different type of TransactionManager:

RawTransactionManager can sign and send transaction (1)
ReadonlyTransactionManager can only read data (no transaction)
ClientTransactionManager can only send a clear transaction to the node and let the node sign it (2)

When you load the contract like you did UsersContract userContract = UsersContract.load(address, admin, credential, ...), behind the scene, Web3J instantiate a RawTransactionManager which will sign the transaction (using the credentials - private key) before sending it to the node.

UsersContract userContract = UsersContract.load("0xc85e6e4b979d05a9b5adbac3e0e7d68b632460d1", admin, credentials, new BigInteger("240000"), new BigInteger("2400000"));

But in your case, you actually need a ClientTransactionManager, so you can directly pass it to the UsersContract.load(...) method like this

ClientTransactionManager transactionManager = new ClientTransactionManager(web3j, newAccountIdentifier.getAccountId());
UsersContract userContract = UsersContract.load("0xc85e6e4b979d05a9b5adbac3e0e7d68b632460d1", admin, transactionManager, new BigInteger("240000"), new BigInteger("2400000"));

Best Answer

Related Solutions

Web3j – Error Processing Transaction: Sender Doesn’t Have Enough Funds

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