File import callback not supported import "./IERC20.sol";

Question

when I try to compile my contract I see errors like this :

DemirelToken.sol

https://eksiup.com/p/4z49413damc3

here's the code :

    pragma solidity ^0.5.0;

import "node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";

contract DemirelToken is ERC20, ERC20Detailed {
    constructor(uint256 initialSupply) ERC20Detailed("Gold", "GLD", 18) public {
        _mint(msg.sender, initialSupply);
    }
}

I get errors like this:

node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20.sol:3:1: ParserError: Source "node_modules/openzeppelin-solidity/contracts/token/ERC20/IERC20.sol" not found: File import callback not supported import "./IERC20.sol"; ^--------------------^ ,node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20.sol:4:1: ParserError: Source "node_modules/openzeppelin-solidity/contracts/math/SafeMath.sol" not found: File import callback not supported import "../../math/SafeMath.sol"; ^-------------------------------^ ,node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol:3:1: ParserError: Source "node_modules/openzeppelin-solidity/contracts/token/ERC20/IERC20.sol" not found: File import callback not supported import "./IERC20.sol";

Answer 1

You need to fix the path in the imports:

pragma solidity ^0.5.0;

import "../node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "../node_modules/openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";

contract DemirelToken is ERC20, ERC20Detailed {
    constructor(uint256 initialSupply) ERC20Detailed("Gold", "GLD", 18) public {
        _mint(msg.sender, initialSupply);
    }
}

Answer 2

Ensure you have installed openzeppelin-solidity in your project

npm install openzeppelin-solidity

Your imports are then as follows:

pragma solidity ^0.5.0;

import "openzeppelin-solidity/contracts/token/ERC20/ERC20.sol";
import "openzeppelin-solidity/contracts/token/ERC20/ERC20Detailed.sol";

contract DemirelToken is ERC20, ERC20Detailed {
    constructor(uint256 initialSupply) ERC20Detailed("Gold", "GLD", 18) public {
        _mint(msg.sender, initialSupply);
    }
}