[Ethereum] Transfer ERC20 token from a smart-contract

erc-20solidity

I am facing an issue and I can't figure what's going wrong.

It is a very simple scenario:

A smart-contract, that implements ERC20 and ERC20Mintable from OpenZeppelin.

pragma solidity ^0.5.0;

import "./openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "./openzeppelin-solidity/contracts/token/ERC20/ERC20Mintable.sol";

contract MyToken is ERC20, ERC20Mintable {}

Another smart-contract that received some MyToken.

pragma solidity ^0.5.0;

import "./MyToken.sol";

contract TokenInteraction {

    address public tokenAddress;

    constructor(address _tokenAdd) public {
        tokenAddress = _tokenAdd;
    }

    function transferToken(address to) public {
        MyToken myToken = MyToken(tokenAddress);
        myToken.transfer(to, 1);
    }

}

I checked that TokenInteraction has more than one token, but when I call transferToken the transaction revert.

I don't understand what's happening.

Many thanks for you help!

EDIT :
Concerning the deployment and the testing methodology, I use Remix IDE on localhost and I deploy on Ganache running locally. To test it, I just mint a token to TokenInteraction and then try to call transferToken to another address

Best Answer

I successfully transferred token with your code. I guess the reason why you encountered problem was a mis-setup at deployment. Please try out the following procedure with Remix IDE to see if it works for you.

Deployment

Deploy MyToken contract
Copy the address of the deployed contract
Deploy TokenInteraction and pass the address copied at step 2 to the constructor.
Once the TokenInteraction contract is deployed, check if tokenAddress matches the address got from step 2

Mint tokens to `TokenInteraction` contract

Copy the address of the deployed TokenInteraction contract.
Select a minter account (by default, the creator of the MyToken contract) and call the mint function with the address from the previous step as well as the amount.
Check with the balanceOf function to verify everything is good.

Transfer tokens to another address

Pass the recipient address when calling transferToken of TokenInteraction contract.

Verify Results

Check the balance of the recipient and that of the TokenInteraction contract.

Related Solutions

[Ethereum] Unable to transfer ERC20 token from another smart contract to the person sending Ether

I can't see what's wrong with the token contract.

Concerning the second one, you should do :

function sendTokens () public payable returns (uint)
    {
        AppleToken appleToken = AppleToken(tokenAddress);
        require(appleToken.transfer(msg.sender, 10));
        return appleToken.balanceOf(msg.sender);
    }

No need to declare the appleToken variable then set it, you can combine both.
Be sure that tokenAddress is the correct one.
Always use a require when doing token transfer! Do not think it works like the transfer method for ether, which handles failure and will throw for you.

EDIT :

I have tested the contracts and it works fine. I think you simply forgot to send tokens to the EquityInvestments contract, hence token balance of msg.sender staying at 0.

[Ethereum] Getting compilation error when trying to use openzeppelin for erc20 token

Most probably, you failed to install node modules properly. I tried using Remix online browser and could easily deploy your contract just changing from local node modules to point github repository of zeppelin.

pragma solidity ^0.4.4;

import "github.com/OpenZeppelin/openzeppelin-solidity/contracts/token/ERC20/MintableToken.sol";

contract SToken is MintableToken {
    string public constant name = "SS Token";
    string public constant symbol = "SKS";
    uint8 public constant decimals = 2;
}

Deployment transaction : https://rinkeby.etherscan.io/tx/0xe31ee332fca077398f562558fc43e1ee02eb9ba909c3be533593fff61539e613

Contract address : https://rinkeby.etherscan.io/address/0xb60f82f7c0967a54cd937f28014ea1614f931782