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Questions tagged [openzeppelin]

OpenZeppelin provides tools to write, deploy and operate decentralized applications. It also protects leading organizations by performing security audits on their systems and products.

OpenZeppelin provides tools to write, deploy and operate decentralized applications.

It also protects leading organizations by performing security audits on their systems and products.

237 questions
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Problem compiling with truffle, stuck on importing openzeppelin

I'm doing a tutorial on blockgeeks and have been stuck for hours. This is the error i get when trying to compile my project Compiling your contracts... =========================== > Compiling @openzeppelin\contracts\token\ERC721\ERC721.sol >…
John Kent
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how to create crowdsale with openzipplin 4.x without crowdsale contracts

i'm new to blockchain development and i was following a tutorial for making an ICO, but he uses openzipplin 2.x and crowdsale contracts that are already implemented on it, i saw on the doc that those contracts are not in the versions 3.x and 4.x, so…
Farouk YD
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ERC721 Tokens with Metadata and Enumerable with Openzeppelin v4.1.0

My question has two parts, I am trying to create an ERC721 token using the Openzeppelin contracts with metadata and that is enumerable. My understanding is after openzeppelin v4.0.0 they removed the ERC721Full.sol contract which included metadata…
Nolan Jannotta
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not found utils/context.sol when i import from openzepplin

i have copied a contract from openzappline. but when i compile it on remix it gives me the error....that utils/context.sol is not found. here is the import pragma solidity ^0.8.0; import "./IERC20.sol"; import…
FSO
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safeTransferFrom does not transfer etherium to the target. ERC-721

I create a contract with ERC-721 and I try to transfer the token with money. I am using web3.js and openzeppelin. So, The transaction is confirmed, but no money is sent to the target wallet. Here is the contract buy function; function buy(uint256…
Gökhan Geyik
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In OpenZeppelin's implementation of ERC20's transferFrom, why is _transfer() called before withdrawer allowance is checked

This is taken from OpenZeppelin's ERC20 transferFrom implementation: function transferFrom(address sender, address recipient, uint256 amount) public virtual override returns (bool) { _transfer(sender, recipient, amount); uint256…
Leeren
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Truffle migrate shows an error on open zeppelin ERC721

I'm very new to truffle and solidity it might be a rookie mistake. When typing truffle migrate --reset, I've got the follow errors : @openzeppelin/contracts/introspection/ERC165.sol:24:5: Warning: Visibility for constructor is ignored. If you…
KevinTale
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How to show withdraw payment amount in MetaMask?

I'm using OpenZeppelin's PullPayment to handle payouts from my eth smart contracts. While withdrawing the coins with MetaMask, MetaMask shows 0 ETH when withdrawing for instance 2 ETH: Is it possible for the payout amount to appear in MetaMask?
Philipp Schweiger
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Installation of openzeppelin/contracts Library

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…
JF0001
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Token contract won't migrate since it is abstract

I'm working on a Dutch Auction style ICO contract and I'm currently trying to migrate an early stage of my ERC20 contract to test the basic features (does it have the correct name, symbol, and decimals). The contract compiles but I can't migrate it…
Christian Volckaert
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Call to super.owner().transfer(msg.value) giving errors

I have a contract that inherits from Open Zeppelin's Ownable contract. There is a method payFees() in my contract that is expected to transfer funds to the owner of the contract. The definition of payFees is as follows function payFees() public…
ngenge
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What does ! mean in Solidity?

I'm studying Solidity and I couldn't understand what does [!] mean in ⑨⑫⑬. What does it mean? And, how to use it? Could you give any advice, please? function sendReward(uint256 _reward, address _dest, uint256 _id) external onlyOwner { …
gnxvw
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How to mint ERC20 token using web3.js library?

I have been working on ERC20 token development. My code is written using solidity and zeppelin frameworks. So far I have used the test networks like Rinkeby, Ropsten to deploy and test all the ERC20 methods. Last night, I have to deploy the smart…
Sriram B
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Openzeppelin ERC20 make revert

my intent is making ERC721 token can transfer by my ERC20 token only the transfer flow is Buyer approve ERC20 to Seller. Seller transfer ERC721 to Buyer. My ERC721 Token's transfer function transfer ERC20 to Seller from Buyer first, and transfer…
Twibap
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Angular - Insert Dynamic Form Content to Database in Zeppelin

I am trying to create a simple dynamic form in Apache Zeppelin using Angular interpreter. I want to pass those values which are coming as input from the form in one notebook to a dynamic MySQL insert query in another notebook. Angular code as given…
Vishnu Mohan
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