Questions tagged [contract-development]
Questions regarding the development of smart contracts
4,450
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Architectural issues of using smart contracts
As part of my master's thesis MVP, I am developing a project on the implementation of an accounting system for electronic document management using smart contracts.
Now there is a question of ...
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7
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Error: Hydration failed because the initial UI does not match what was rendered on the server, Wagmi and Nextjs
I was trying to implement wagmi in my dapp, after I copied the example in the documentation https://wagmi.sh/examples/connect-wallet, I got this error: Error: Hydration failed because the initial UI ...
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1
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11
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Display Value in Remix
I am a newbie in Solidity. Below is the simple Solidity source code
pragma solidity ^0.4.21;
contract CAT {
event XYZ (uint Z ) ;
uint[] x;
uint a ;
function f(uint[] memoryArray) ...
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1
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10
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Parameter function in Solidity
I am a newbie in Solidity. Below is the snippet of code I came across :-
pragma solidity ^0.4.0; contract C { //1
function f(uint len) { //...
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3
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26
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+200
Is it possible for a callee to DOS a function call if the caller ignores the success value?
Consider the following function:
uint256 mySpecialNumber = 0;
function foo(address callee, uint256 newNumber) public {
mySpecialNumber = newNumber;
// make a low level call to the bar() function ...
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1
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27
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How to call an undeployed contract from a solidity code that only implements a constructor
I've two contracts, and I want to call a contract from another contract. I've two ways to do it, as described here
but, my case is different, the callee contract only implements the constructor inside ...
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Is there any way to get autocomplete for Solidity function definitions in JavaScript?
By autocomplete I mean something akin to how functions that would be declared in JavaScript get prompts/autocomplete in IDEs.
(Also, I'm using VS Code)
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Warning when returning no bytes data with checkUpkeep in Chainlink Keeper
From:
@chainlink/contracts/src/v0.8/interfaces/KeeperCompatibleInterface.sol";
When using:
checkUpkeep(..) .. override returns (bool upkeepNeeded, bytes memory /* performData */)
I'm not ...
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2
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2
answers
46
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How to instantiate contract instances with ethers.js and alchemy-sdk
(Found this from the public Alchemy discord, and wanted to ask the question here so it can get indexed online 💙)
I'm trying to instantiate contracts in my javascript code so that I can call ABI ...
- 283
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1
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Chainlink Keepers not Upkeeping after i enterLottery. Can you spot issue that would be causing this?
I've spent many weeks on this project trying to figure out why "Chainlink Keepers" is not working. I can successfully deploy and verify the contract on Rinkeby. Then i do the following...
1.)...
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Utilizing and Monetizing existing NFTs using Magazine
I’m working on a side project, A Meta Magazine, featuring NFTs only. This is a collaborative project
which utilizes existing NFTs. Entire Mag will be made out using NFTs, including cover pages, ...
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1
answer
107
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+50
Update HashMap within onERC721Received with Vyper
When a contract receives an NFT by calling safeTransferFrom, onERC721Received is automatically called on the receiving contract. I want to be able to update a Hashmap to record the address of the ...
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1
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26
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What should I do to mint 2000 items?
When I try to mint 2000 items in remix I get this error:
Gas estimation errored with the following message (see below). The
transaction execution will likely fail. Do you want to force sending?
...
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1
answer
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After deploying a smart contract, if I have 2,000 items, is it possible to mint all of them at the same time?
If I have 2,000 items, is it possible to mint all of them at the same time, or is there a limit for the number of items that I want to mint at the same time?
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i have been trying to deploy mocks for my hardhat-raffle , but i encountered this problem
const { network, ethers } = require("hardhat")
const {developmentChains} =require('../helper-hardhat-config')
const BASE_FEE=ethers.utils.parseEther("0.25") // 0.25 is the premium ...
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How to split bytes from calldata and convert into memory variables?
Assume calldata for my smart contract being address as bytes, and few amounts as bytes chained together.
How can I extract the bytes for address and store it in
address memory address_ =
and the ...
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0
answers
14
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there are different addresses who are making there todo list on solidty, my task is to findout which address is writing which to do list?i [closed]
pragma solidity ^0.8.15;
//SPDX-License-Identifier:unlicense
contract arrayupdatedeleteadd{
string[] myarray3;
address owner = msg.sender;
mapping(address => string[]) addressfromarray;
...
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1
answer
22
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How to get index from Mapping array in Solidity/Remix?
I can push worker address to mapping with manager address. I try to get manager address like this code.
contract Test {
struct Worker{
address manager_add;
address worker_add;
}...
- 103
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1
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A few simple question about using interfaces vs. standard contracts (IERC721 vs. ERC721)
1.)Is it correct to say..... if i import ERC721.sol into my contract then all the ERC721.sol functions are accessible even if i don't list all the functions in the contract? Meaning... i don't ...
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Solidity interface error
I am trying to connect two different Smart Contracts using interfaces. Here is my contract CRUD.sol: // SPDX-License-Identifier: MIT pragma solidity ^0.8.4;
contract CRUD {
struct Data {
uint id;
...
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16
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Are 'suspended' transactions even possible?
newbie here, toying with the idea of some gambling game, nft-based.
Suppose I want users to gamble on their own NFTs. Obviously I want the actual transaction to occur only if the player loses. I guess ...
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2
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37
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Function Max mint per wallet is not working
learning solidity and curious how i can limit the minting of my NFT to only 2 per wallet address. Trying to prevent people from minting more then 2 tokens during free mint phase using "mapping&...
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Error during Ethereum solidity NFT contract execution [Out of gas]?
We have a Rinkeby contract for minting NFTs. Occasionally, when it's in public-sale mode, if a person attempts to mint an NFT, the transaction fails and on the tx's etherscan it says:
Warning! Error ...
- 103
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1
answer
13
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Multiple inheritance in Solidity
I have a contract C that is Ownable so I can use ownerOnly on its admin functions.
Recently, I added some functionality that I'm going to start using in other projects. I refactored the functionality ...
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3
answers
104
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Do we still need centrallize database at all for Dapp development?
This question keeps popping up in my mind, do we need centralize database at all for Dapp development like PostgreSQL, MongoDB and more, what if we want to store user's email and send them email ...
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12
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Understanding local variables named as same in diffrent functions and modifiers
I'm confused while understanding the local variable _txId is used in several functions and modifiers, do they all have the same value or are they independent for each call.
I read that local variables ...
- 24
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18
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Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'eth')
I am following what seems a relatively simple tutorial to create a smartcontract, however, I am getting the above error and I am stumped as to what is causing it
Below is my html file
<!DOCTYPE ...
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1
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15
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if vs require - Predict the future challenge
this is my first message here!
I've been trying to solve this challenge: https://capturetheether.com/challenges/lotteries/predict-the-future/, and I don't understand why I was able to solve it only ...
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2
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37
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Solidity interface between two contracts
i am trying to connect two different Smart Contracts. On one hand I have CRUD.sol, which implements CRUD operations in a struct "Data". I have programmed a method readAllData() that returns ...
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What determines when etherscan will automatically verify a contract?
As I understand it, etherscan will look at the bytecode and automatically verify contracts similar to ones its seen before. My question is, how does it make this decision? Does it verify only ...
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1
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Permit in a stablecoin
I am trying around and writing a kind of new stablecoin code. How should a permit function look like so it is correctly embedded and secure against any fraudulent usages?
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How can I check the previous values of smart contract variables?
If I have a variable uint public data = 42;
and in the next invocation of a smart contract's function, this is now data=43.
Can I somehow check and find the previous value (i.e., data=42) ??? Where ...
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2
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26
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Pls how do I create a nested array in solidity
I was trying to create a contract that has multiple rooms, in each room there would be some amount of players. Pls how do I acheive this? This is my approach but it's not working. I am unable to ...
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Impementing AggregatorV3Interface into the contract throws Error: cannot estimate gas
I have a working contract deployed on rinkeby, I'm trying to add there a function to get the current ETH/USD price using ChainLink's AggregatorV3Interface .
When testing the needed function in Remix, (...
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Trying to connect my smart contract with my front end
I am building a basic DAO program. My smart contracts are mostly finished and my front end is mostly finished except for of course the blockchain elements. Before I jump into my current problem I will ...
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0
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27
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Make a struct returned by ethers.js writable?
In my smart contract, I keep some contract metadata in a struct called _data. What I want to build is a mechanism to retrieve this metadata, make required changes, and then write the struct back to ...
- 507
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1
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Is Ethereum the best platform for my project? [closed]
I'm a newbie in the blockchain world and I was wondering if I could jog your brains.
I'm currently trying to run a few drones using blockchain and smart contracts, but I'm unsure which platform to ...
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1
answer
11
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Block.number - how to fetch it correctly
I want to get the current block number of all blocks.
If I run return block.number it only returns me the number of blocks since the last deploy.
Why is it like that?
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27
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Attempting to connect my smart contract with my front end
I am attempting to build a basic DAO program. My smart contracts are mostly finished and my front end is mostly finished except for of course the blockchain elements. Before I jump into my current ...
1
vote
1
answer
31
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How to sort off-chain
I read this article about sorting an array on an off-chain backend, but there are some things I can't wrap my head around.
For example, say I have an array of times in no particular order arr ...
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1
answer
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View contract creation param
I'm trying to find the contract creation param on this one: https://rinkeby.etherscan.io/address/0xdbc4949a84cd92c482af74d8813c13588e466841#code
But I couldn't find it on etherscan, where can I find ...
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How to implement a custom token in a seperate contract
I am new to programming and attempting to design a very basic DAO which implements a native token for voting (as you'll see it is unfinished). Help would be greatly appreciated. I am currently running ...
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17
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Execution reverted while trying to read a variable
I'm playing Ethernaut Level3, the full contract is here: https://ethernaut.openzeppelin.com/level/0x4dF32584890A0026e56f7535d0f2C6486753624f
In truffle I first created a simplified contract:
// SPDX-...
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18
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How to copy contract from mainnet to local node without source code?
I'm deploying contract A locally. I got contract A source code from polygonscan. Contract A has the library IterableMapping as a dependency, and that library doesn't have its source code verified, so ...
- 103
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2
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40
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Solidity Returning Array of Struct Error
I want to return an array of structs because i want to output all my data.
//SPDX-License-Identifier:MIT
pragma solidity ^0.8.0;
contract MyContract
{
mapping(uint256 => People) dataList;
...
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2
answers
25
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How to write a getter function for an array of structs? "storage ref[] storage ref is not implicitly convertible to expected type uint256[]"
I'm developing an app that allows user to make bets against each other.
In order to get some useful web-UI info, i need to write a getter function for an array of structs.
Simplified version of my ...
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2
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43
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Implement splitting payment in ERC-20 token
I am new to this topic. I'm trying to implement a method to split the payment inside the token contract itself. I know that there is a separate contract for payment splitting, but I want to try to ...
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2
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25
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Why do smart contracts have to be deterministic?
I was wondering why smart contracts have to be deterministic. As I understand it, to deploy a smart contract you just send it as the payload of a transaction without specifying a recipient. It's then ...
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In Brownie, Do you need always need .address to use a contract as an contract address variable
new to Brownie as I have been using mostly tutorials. I am trying to use a contract address as a variable to deploy another one, and want to know does adding the ".address" e.g : ContractXY....
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1
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29
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Different between send() and sendTransaction()
I'm wondering the difference between send() and sendTransaction() in web3. Take the following test code as example:
Contract:
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.0;
contract ...
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