Questions tagged [openzeppelin-contracts]
OpenZeppelin Contracts is a library for secure smart contract development. It provides implementations of standards like ERC20 and ERC721 which you can deploy as-is or extend to suit your needs, as well as Solidity components to build custom contracts and more complex decentralized systems.
68
questions
0
votes
0answers
13 views
Token transfer lock after crowdsale
I am faced with a problem regarding the ICO and Token smart contracts (SCs). I am currently using OpenZeppelin SCs to create my token and ICO and everything is working fine. Now I would like to add a ...
0
votes
0answers
15 views
zeppelin tutorial smart contract (noob alert) can't connect to network
I am following this tutorial -
https://docs.openzeppelin.com/learn/deploying-and-interacting#local-blockchain
Everything was going good until i was asked to type the command -
$npx oz accounts - ...
0
votes
2answers
100 views
Super simple token with Open Zeppelin
I want to create a super simple token for my community. I read some tutorials and I found this code:
pragma solidity ^0.5.2;
import "./lib/oz/contracts/token/ERC20/ERC20Pausable.sol";
import "./lib/...
0
votes
2answers
115 views
Sign message with web3 and verify with openzeppelin-solidity ECDSA.sol
I'm trying to get a little example working with ECDSA.sol here: https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/cryptography/ECDSA.sol
This contract:
Generate a random(...
1
vote
2answers
53 views
ERC20 not recognized by TokenTracker
I have deployed ERC20 with reference to
// File: openzeppelin- zos/contracts/token/ERC20/DetailedMintableToken.sol
I called the initialized function with owner, name, symbol and decimal value. ...
0
votes
1answer
46 views
ERC20Mintable contract call return wrong number
I use OpenZeppilin ERC20Mintable contract and add MaxSupply parameter to contraint the ERC20 token amount allowed to issue.
what I want is only permit contract ower to view MaxSupply info, my ...
1
vote
1answer
67 views
How to initialize inherited contract
I find there is a contract named ERC20Capped inherited from ERC20Mintable in zippelin contract project.
Both of them have their own construction parameters.How to assign value to them during contract ...
1
vote
1answer
179 views
can etherscan.io show local ganache transaction details?
I am purchasing tokens on my sample Dapp with ganache-cli account using metamask.
Metamask shows the confirm message and deduct the ether from total balance but in token section it still not update ...
0
votes
2answers
1k views
File import callback not supported import “./IERC20.sol”;
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-...
0
votes
2answers
46 views
ERC721 exchange logic
I'm trying to allow NFT holders to sell their tokens by listing prices (ETH) and allow others to buy those listed tokens.
I used openzeppelin and succesfully implemented and tested my token creation. ...
0
votes
1answer
109 views
How to use function modifier to control contract function access right?
I deployed a ERC20Mintable token in truffle environment(the source file is ERC20Mintable.sol).
The mint function is declared with onlyMinter modifer:
contract ERC20Mintable is ERC20, MinterRole {
...
1
vote
1answer
48 views
ERC721 Metadata and Items
i'm new to ERC721 tokens so this may be a stupid question.
Following the Opensea docs and other docs (for example openzeppelin ones), I just create a simple ERC721 token that i called "avatar" which ...
1
vote
1answer
63 views
Error installing zos-lib@2.4.0
I am working through the tutorial for zeppelin-os found here: https://docs.zeppelinos.org/docs/linking.html
and have an error when running zos create
Could not find file zos-lib/contracts/...
2
votes
2answers
343 views
What's the difference between Truffle Migrations and ZeppelinOS upgradeable contracts?
It was my understanding that Truffle migrations will move updated contracts to new addresses. As a developer, you can use this feature to update already deployed contracts with new code.
ZeppelinOS ...
1
vote
1answer
50 views
how can I use takeOwnership function?
currently, I'm using openzeppelin.
I can't find takeOwnership function in lately ERC721 interface.
takeOwnership function deprecated?
(I cant' find any document)
so, how can I do that like ...
2
votes
2answers
187 views
low-level call failed
I'm using the crowdsale contract (https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/crowdsale/Crowdsale.sol). I have deployed a detailedERC20 smart contract. When I send the ...
1
vote
1answer
90 views
Transfer erc721 token to another address
I'm currently using transferFrom / safeTransferFrom to transfer the token to another address but I encounter this error.
Error:
Error: invalid address (arg="to", coderType="address", value="...
3
votes
2answers
138 views
How to test events that were sent by inner transaction / delegate call?
Usually, using truffle I can check for events like this:
let { logs } = await myContract.doSomethingImportant( xxx );
// 1500 tokens are expected to get
expectEvent.inLogs(logs, '...
3
votes
1answer
128 views
Compilation error using SafeMath
I am trying to do subtraction operation using the SafeMath library. The following is my code:
pragma solidity ^0.5.1;
library SafeMath {
function sub(uint256 a, uint256 b) internal pure returns (...
1
vote
1answer
202 views
Updating ERC20 Contract from 0.4.0 to 0.6.0
Im updating some ERC20 contact code from solidity 0.4.0 to 0.6.0 and hitting some snags as it seems openzeppeling has changed its structure since then as can be expected.
I cant access the balances ...
1
vote
1answer
46 views
ERC20 finishMinting() after ICO
When ICO is finalized, I call finishMinting() to prevent from adding new tokens to totalSupply.
contract MyTokenCrowdsale is Crowdsale, MintedCrowdsale, CappedCrowdsale, TimedCrowdsale, ...
1
vote
1answer
32 views
ERC20 RefundableCrowdsale
I have a crowdsale contract that inherits RefundableCrowdsale.sol from OpenZeppelin. I was using their v1.10.0 initially, but now revamping it using v1.12.0.
contract TestTokenCrowdsale is Crowdsale,...
1
vote
1answer
60 views
ERC721Token super._mint calls addTokenTo from the top level implementation
Based on Shawn's answer,
super._mint calls addTokenTo from the top level implementation (ERC721Token).
How does this work?
super._mint calls _mint from ERC721BasicToken
reads line addTokenTo
...
1
vote
1answer
119 views
ERC721 how does tokenOfOwnerByIndex() list tokens owned by a user?
Per eip-721, there's an optional "enumeration extension". So what I did was I called balanceOf to get the number of tokens owned by the account and called tokenOfOwnerByIndex in a loop to get each ...
1
vote
1answer
208 views
openzeppelin,VM Exception while processing transaction: revert
using openzeppelin-solidity to create crowdsale.
Then I use this statement to Buy Token:
MyCrowdsaleInstance.sendTransaction({
from: purchaser[1],
value: web3.utils.toWei("0.5", "ether"),
...
1
vote
1answer
77 views
ParserError: Expected token Semicolon
I got this particular Parser error and can you help me how to fix this issue:while using this code
pragma solidity ^0.4.17;
import "../node_modules/zeppelin-solidity/contracts/token/ERC20/...
1
vote
2answers
77 views
OpenZeppelin contract not working on Kovan testnet
I created a simple smart contract using OpenZeppelin and deployed the contract to the Kovan testnet. However, when I send KEth to the contract using MetaMask, nothing happens (I believe the buyTokens ...
0
votes
1answer
49 views
DeclarationError: Identifier not found or not unique and Undeclared identifier
I am trying to create a crowdsale contract using zeppelin. But i am facing following errors.
CrowdSale.sol:6:46: DeclarationError: Identifier not found or not unique.
contract EdCoinCrowdSale is ...
1
vote
1answer
450 views
Solidity 0.5.2 - OpenZeppelin - New SafeERC20 callOptionalReturn(token,data)
i've been trying to mix ERC20 functionality with ERC223 function overloading technique and create a bridge for backwards compatibility using SafeERC20.
For relevancy sake i renamed SafeERC20 into ...
0
votes
1answer
215 views
How to use 2 different constructors with open-zeppelin
I don't understand well how to implement an smart contract to create a capped Token.
If I want to follow the example of a simple token is easy:
https://github.com/OpenZeppelin/openzeppelin-solidity/...
0
votes
1answer
60 views
Minted Crowdsale vs Non Minted Crowdsale
I am exploring openzeppelinr-solidity smart contracts for Initial Coin Offering(ICO). There are two options available for a token smart contract one is to have hardcoded total supply tokens or mint a ...
1
vote
1answer
413 views
How to Issue /Mint / Generate additional tokens? Contract is mintable
I have Token on ropsten network (https://ropsten.etherscan.io/token/0x975FB1824F82E446DD3F5c4cb04474468ED7d878) which is Mintable with initial supply of 10B and Mintable Cap up to 50B.
My ether ...
1
vote
1answer
44 views
How to burn non burnable ERC20?
Suppose you received 250 HELLOCoins and you want to burn them. Unfortunately, HELLOCoins uses OpenZeppelin ERC20 which implements the following function:
function _transfer(address from, address to,...
1
vote
1answer
269 views
Importing in SOLC to deploy smart contract
I don't run an Ethereum framework like Truffle and I want to deploy a smart contract using infura node.
The smart contract is very simple:
pragma solidity ^0.5.2;
import "http://github.com/...
0
votes
1answer
38 views
What does the single line “_;” in OpenZeppelin's onlyMinter() function do? [duplicate]
In onlyMinter(), there is a line with only _;. I'm having troubles adding a minter address, so I'm just checking the various contracts that go into ERC721. The function is
modifier onlyMinter() {
...
1
vote
0answers
78 views
No events were emitted - Exchanging ERC721 Tokens
Function to exchange ERC721 Tokens between two addresses. I am implementing this on truffle and openzeppelin 2.10. Two different tokens should be exchanged between two addresses.
Here's my contract ...
1
vote
1answer
289 views
How to ERC721 token using external contract to msg.sender?
I have Caller and ERC721 contract just like this :
contract SampleToken is ERC721MetadataMintable {
string private name;
string private symbol;
constructor (address _creator, string _name,...
0
votes
0answers
129 views
Struct Mapping: DeclarationError: Identifier not found or not unique for
Using openzepplin version 2.0.0 and solc version 0.5. I am writing an ERC721 token contract on truffle. Truffle compiles with no error on solc 0.4.23. I had to upgrade to 0.5 due to openzepplin ...
1
vote
2answers
368 views
OpenZeppelin Starting Balance
I believe that the openzeppelin project have updated their StandardToken smart contract which is now called ERC20.sol.
One issue that I have is that the new smart contract has some missing ...
3
votes
2answers
233 views
OpenZeppelin crowdsale token ownership
Using the non-modified OpenZeppelin code to create a mintable and burnable ERC20 token and a crowdsale contract, once ownership of the token is transferred to the crowdsale contract, is it possible to ...
1
vote
2answers
46 views
Make a crowdsale reusable?
I have a pretty standard OpenZeppelin crowdsale. Now the issue is that I want to be able to use one crowdsale contract with multiple (~100) different ERC20 tokens.
Ideally I want to put the ...
1
vote
1answer
858 views
Truffle compile gives Parser Error: Error parsing openzeppelin-solidity/contracts/ownership/Ownable.sol
I installed the latest version of truffle, solc, node and also installed new version of openzeppelin-solidity library in my project.
Changed the truffle-config.js to use new solc version. My contract ...
1
vote
1answer
144 views
Issue in comparing token contract address and address(0) in Solidity 0.5.0
I am trying to compare the token contract address with the address(0). This was working fine in older version of truffle and solidity compiler (0.4.24). When I upgraded truffle and started using the ...
3
votes
0answers
221 views
Questions on MinterRole contract in openzeppelin
I am using the openzeppelin for creating the ICO contract. I am concerned about the MinterRole here. After I develop Token contract, I added the sale contract as a minter using "addMinter" function.
...
1
vote
0answers
9 views
IncreasingPriceCrowdsale breaking TimedCrowdsale
For reasons I can't figure out why open-zeppelin's IncreasingPriceCrowdsale and TimedCrowdsale seem to be conflicting with each other. Here is a basic version of the Crowdsale contract I'm working ...
1
vote
1answer
48 views
Set rate for crowdsale after it has ended
The problem I am trying to solve is how to properly price an ICO.
One idea would be to have 10 tokens available. Do the ICO and collect all the ETH. Then after the ICO has ended, divvy up the tokens ...
0
votes
1answer
48 views
How to automatically deliver the tokens in a PostDeliveryCrowdsale
My goal is to deliver the tokens only at the end of the crowd sale. I have seen the below code which can deliver the tokens in a batch.
Questions
Will this work even when there is a million _to ...
1
vote
1answer
120 views
Running Openzepplin from docker
I am trying to build a docker image using open zepplin libraries. It works until it has to import the zepellin library, for which it can't seem to find.
Here is what my docker image looks like :
...
0
votes
2answers
79 views
(Truffle) how to call finalize() function after finishing crowdsale
I would like to call token.transferOwnership(msg.sender) after finishing timed crowdsale. So, I inherited FinalizableCrowdsale contract, then override finalization() function to call transferOwnership ...
2
votes
1answer
95 views
Issue in understanding MintedCrowdsale in the ICO contract from openzeppelin
I am trying to understand the openzeppelin code for writing ICO contract.
In MintedCrowdsale, mint() function in ERC20Mintable is called as mentioned below.
ERC20Mintable(address(token())).mint(...
