[Ethereum] Installation of openzeppelin/contracts Library

go-ethereumopenzeppelinopenzeppelin-contractstruffle

I have created a node.js project, within which I have created a truffle directory and initialised its project. I have installed the openzeppelin (npm install @openzeppelin/contracts) library in this truffle project directory, but nothing appears to have been installed, although I did not received any error during the install process. The import statement in my project displays the error hereafter:

import "@openzeppelin/contracts/token/ERC721/ERC721Full.sol";

Source "@openzeppelin/contracts/token/ERC721/ERC721Full.sol" not found: File import callback not supported

Thank you. J

Best Answer

If you run npm uninstall @openzeppelin/contracts and then npm install @openzeppelin/contracts@2.3.0, then retry the import, then it should work.

Also, check your truffle-config.js file and see if the root directory is configured properly to find your node_modules folder properly.

Related Solutions

Contract Deployment – Importing in SOLC to Deploy Smart Contract

solc can't get things over a network - it can only import local files, which was your initial error.

I'm assuming your npm install step is still leading to failure because the compiler is still looking in the wrong place. (I'd assume the OpenZeppelin stuff has gone into the node_modules folder.)

Take a look at how to manually map in localised - i.e. downloaded/cloned - files by passing the relevant options to solc.

An example from the documentation:

> solc github.com/ethereum/dapp-bin/=/usr/local/dapp-bin/ source.sol

(Remix, being an IDE, has the in-built intelligence to know how to pull files from GitHub prior to the compilation step.)

Truffle – File Import Callback Not Supported: How to Resolve ‘import ./IERC20.sol;’ Issue

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);
    }
}

Best Answer

Related Solutions

Contract Deployment – Importing in SOLC to Deploy Smart Contract

Truffle – File Import Callback Not Supported: How to Resolve ‘import ./IERC20.sol;’ Issue

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