I have two Ethereum generated accounts I am managing and need to programmatically send tokens between the two accounts.
I've created two accounts and can send ERC20 tokens from a contract to an address but need to send from addresses to addresses. I am using the sample solidity token on the Ethereum website.
It has a function called transfer to send tokens between accounts:
function transfer(address _to, uint256 _value)
I need to now connect to this contract using web3, and then send a certain number of tokens generated to another account. I've been struggling with how to do this for quite some time and hoping this community could help. Here is what I have thus far, using web3 version 0.20.0:
const Web3 = require("web3");
const web3 = new Web3();
web3.setProvider(new
web3.providers.HttpProvider("https://ropsten.infura.io/XXXXXX"));
var abi = [ {} ] // redacted on purpose
const account1 = "0x9..."
const account2 = "0x3..."
var count = web3.eth.getTransactionCount(account1);
var abiArray = abi;
var contractAddress = "0x2...";
var contract = web3.eth.contract(abiArray).at(contractAddress);
var data = contract.transfer.getData(account2, 10000, {from: account1});
var gasPrice = web3.eth.gasPrice;
var gasLimit = 90000;
var rawTransaction = {
"from": account1,
"nonce": web3.toHex(count),
"gasPrice": web3.toHex(gasPrice),
"gasLimit": web3.toHex(gasLimit),
"to": account2,
"value": 0,
"data": data,
"chainId": 0x03
};
var privKey = new Buffer('XXXXXXXXXXXXXX', 'hex');
var tx = new Tx(rawTransaction);
tx.sign(privKey);
var serializedTx = tx.serialize();
web3.eth.sendRawTransaction('0x' + serializedTx.toString('hex'), function(err, hash) {
if (!err)
console.log(hash);
else
console.log(err);
});
This code however, does not transfer from one account to the other.
Code for Token Contract:
contract Token {
// Public variables of the token
string public name;
string public symbol;
uint8 public decimals = 18;
// 18 decimals is the strongly suggested default, avoid changing it
uint256 public totalSupply;
// This creates an array with all balances
mapping (address => uint256) public balanceOf;
mapping (address => mapping (address => uint256)) public allowance;
// This generates a public event on the blockchain that will notify clients
event Transfer(address indexed from, address indexed to, uint256 value);
// This notifies clients about the amount burnt
event Burn(address indexed from, uint256 value);
/**
* Constrctor function
*
* Initializes contract with initial supply tokens to the creator of the contract
*/
function Token(
uint256 initialSupply,
string tokenName,
string tokenSymbol
) public {
totalSupply = initialSupply * 10 ** uint256(decimals); // Update total supply with the decimal amount
balanceOf[msg.sender] = totalSupply; // Give the creator all initial tokens
name = tokenName; // Set the name for display purposes
symbol = tokenSymbol; // Set the symbol for display purposes
}
/**
* Internal transfer, only can be called by this contract
*/
function _transfer(address _from, address _to, uint _value) internal {
// Prevent transfer to 0x0 address. Use burn() instead
require(_to != 0x0);
// Check if the sender has enough
require(balanceOf[_from] >= _value);
// Check for overflows
require(balanceOf[_to] + _value > balanceOf[_to]);
// Save this for an assertion in the future
uint previousBalances = balanceOf[_from] + balanceOf[_to];
// Subtract from the sender
balanceOf[_from] -= _value;
// Add the same to the recipient
balanceOf[_to] += _value;
Transfer(_from, _to, _value);
// Asserts are used to use static analysis to find bugs in your code. They should never fail
assert(balanceOf[_from] + balanceOf[_to] == previousBalances);
}
/**
* Transfer tokens
*
* Send `_value` tokens to `_to` from your account
*
* @param _to The address of the recipient
* @param _value the amount to send
*/
function transfer(address _to, uint256 _value) public {
_transfer(msg.sender, _to, _value);
}
/**
* Transfer tokens from other address
*
* Send `_value` tokens to `_to` in behalf of `_from`
*
* @param _from The address of the sender
* @param _to The address of the recipient
* @param _value the amount to send
*/
function transferFrom(address _from, address _to, uint256 _value) public returns (bool success) {
require(_value <= allowance[_from][msg.sender]); // Check allowance
allowance[_from][msg.sender] -= _value;
_transfer(_from, _to, _value);
return true;
}
/**
* Set allowance for other address
*
* Allows `_spender` to spend no more than `_value` tokens in your behalf
*
* @param _spender The address authorized to spend
* @param _value the max amount they can spend
*/
function approve(address _spender, uint256 _value) public
returns (bool success) {
allowance[msg.sender][_spender] = _value;
return true;
}
/**
* Set allowance for other address and notify
*
* Allows `_spender` to spend no more than `_value` tokens in your behalf, and then ping the contract about it
*
* @param _spender The address authorized to spend
* @param _value the max amount they can spend
* @param _extraData some extra information to send to the approved contract
*/
function approveAndCall(address _spender, uint256 _value, bytes _extraData)
public
returns (bool success) {
tokenRecipient spender = tokenRecipient(_spender);
if (approve(_spender, _value)) {
spender.receiveApproval(msg.sender, _value, this, _extraData);
return true;
}
}
/**
* Destroy tokens
*
* Remove `_value` tokens from the system irreversibly
*
* @param _value the amount of money to burn
*/
function burn(uint256 _value) public returns (bool success) {
require(balanceOf[msg.sender] >= _value); // Check if the sender has enough
balanceOf[msg.sender] -= _value; // Subtract from the sender
totalSupply -= _value; // Updates totalSupply
Burn(msg.sender, _value);
return true;
}
/**
* Destroy tokens from other ccount
*
* Remove `_value` tokens from the system irreversibly on behalf of `_from`.
*
* @param _from the address of the sender
* @param _value the amount of money to burn
*/
function burnFrom(address _from, uint256 _value) public returns (bool success) {
require(balanceOf[_from] >= _value); // Check if the targeted balance is enough
require(_value <= allowance[_from][msg.sender]); // Check allowance
balanceOf[_from] -= _value; // Subtract from the targeted balance
allowance[_from][msg.sender] -= _value; // Subtract from the sender's allowance
totalSupply -= _value; // Update totalSupply
Burn(_from, _value);
return true;
}
}
contract.transfer(account2, 10000, {from: account1});