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I'm developing a Smart contract. In this Smart contract, I have one method called 'put' which creates a new Type when it doesn't exists and then adds it to a mapping (name <-> type). But after ...

I'm receiving an internal error when attempting to place an order on the Avalanche chain. Url: https://api.0x.org/orderbook/v1/order Error: { "code": 100, "reason": "...

Here is some code to connect to a geth authority using web3py: >>> from web3.auto.gethdev import w3 # confirm that the connection succeeded >>> w3.isConnected() True When I run ...

My goal is to compare my IERC20 contract with my address repaymentCurrency in a require statement: require(currency == listing.loanDetails.repaymentCurrency, "Error"); However, I keep ...

The fundamental reason that Ethereum and Bitcoin use different metrics to maintain the size of their blocks. Any help will be appreciated!

I am interacting with the Harmony testnet using web3j, but since Harmony has 4 shards i also have to specify the chainID, otherwise it throw an error. When writing to the blockchain i was able of ...

My contract is a safemoon fork. He must tax transactions, accumulate some tokens and sell these tokens by BNB to send to the 4 wallets in the code. Turns out he must sell the tokens when he hits a ...

Please can anyone explain to me how to set up a node so I can connect to Devnet2 ? I'm following the instructions here. I've also tried running Geth in the terminal and get stuck on IPC location path. ...

Metamask has mainnet installed, while testnets are hidden by default. But what details are required when adding a custom network to connect to the Polygon (Matic) network via Metamask? Are there any ...

constructor () Auth(msg.sender) { router = IDEXRouter(0x10ED43C718714eb63d5aA57B78B54704E256024E); pair = IDEXFactory(router.factory()).createPair(WBNB, address(this)); _allowances[address(this)][...

I am going through brownie_fund_me part of this course: https://github.com/PatrickAlphaC/brownie_fund_me The initial deploy,.py works properly, but I keep getting some variation of invalid opcode and ...

I am building a middleware contract to interact with 0x. but I can't find which function to use in the 0x contract. could anyone help me? can anyone explain how 0x swap tokens on contract level?

I recently started mining with some left-over GPU time. My server is running Ubuntu. nvidia-docker run --memory="7g" -d kriation/ethminer -P stratum1+ssl://...

I'm deliving into NFTs and smart contracts I've deployed a simple NFT contract as a test usiing OpenZeppelin and Remix and the token Burn function is internal - if I, as the owner and creator of the ...

I want to run my tests on testnet, mainly because I need to test chainlink VRF. How can I do that? this is my hardhat.config.js: require("@nomiclabs/hardhat-ethers"); require("@...

Apologies if this is a bit of a noob question. But I have a bit of trouble understanding a concept. I am designing a Smart Contract where I need to send data for the same transaction from multiple ...

I have been trying to send a tx using nodejs for some time now, however the tx only output’s the transaction hash but it is never confirmed or mined, I am using the following params for the same { ...

I am experiencing a weird situation where it seems that the Solidity compiler (or optimizer) is removing an external call. I am performing an ERC20 token transfer on forked mainnet using Hardhat. From ...

Can anybody suggests the way to retrieve an Uniswap pair sell or buy transactions, filtering the events logs. I know, it's possible to monitor an token transfers continuously scanning token Transfer ...

Let's say Bob has 1 token minted based on ERC1155. How can Bob or others distinguish Bob's token btw NFT and FT? Or is his token can be both NFT or FT? Please correct me.

I'm trying to add a function to the ERC721 Smart Contract to return all the NFTs (items identified by tokenID) from a user address. At first, I was thinking on something like the following: ...

I'm looking to build an ERC1155 smart contract (I'm using OpenZeppelin) that will contain NFTs whose metadata will be hosted on IPFS. About 4,000 images for now, all unique (all amount of 1). An ...

My idea is to ask users what amount they want to tip another user. However I want to take 5% of that amount and send it to another address (as comission for site operator) I know the user would have ...

I'm trying to check when a metamask account changes within my application. However the features I found are not working, for example I am using the 2 new methods as an example below: // not works ...

Total crypto newb here, I would appreciate some clarifications about the tokenid on both the ethereum and polygon blockchains. I keep seeing this definition of tokenid, is the tokenid made up of the ...

I am looking for a basic javascript example on how to send money using metamask from within my app

I've installed truffle globally with 0 vulnerabilities (after npm audit fix). I'm going through a tutorial where I am using Truffle as a dependency — and when running npm install, it installs it ...

Is it possible for my NFT contract deployed on Polygon to see if a user (msg.sender) has an NFT on the Ethereum mainnet. For example, if I wanted my NFT contract to give some sort of 'bonus' to all ...

Can someone please explain the significance of the location of the "await" keyword in the "expect" function from the waffle testing framework? for example: this passes (assume its ...

(web3js) Let's say I have the below data (specifications here). { ... hash: '0x86bc6fef9a3009f377a3a66b7fa654b3e498f4af46c297eab86346b3e5eabd7c', nonce: '0x2ed', value: '0x0', ...

Let us consider a following contract generated by the wizard // SPDX-License-Identifier: MIT pragma solidity ^0.8.2; import "@openzeppelin/contracts/token/ERC20/ERC20.sol"; contract ...

I am a bit confused cause I see everyone having tutorials on creating their own marketplace AND in OpenSea I don't see a list button only a create button. I want to create my own smart contract to ...

Transaction hash: 0x9e4cd796a7f3a299ef412f8268e839e8a1600e01140bd2258d8a9d12ee5bf642 Transaction request we are sending to swap: { allowanceTarget: "0xdef1c0ded9bec7f1a1670819833240f027b25eff&...

I keep getting the below error when I request data from my node. error": "rejecting job bd25ae01d8604b268abfbfa764399511 with payment 100000000000000000 below minimum threshold (...

I am using 0x API for my dex and I am expecting at least 4k users on my app. But I don't see any subscription plan or anything on 0x documentation to increase or at least know my API rate limits. Is ...

Let us consider the following setup. Alice executes a method doStuff(...) of a particular smart contract deployed to an EVM blockchain under address 0x0123456789. Execution of that method resulted ...

Hi I have a question for with respect to Ethereum Virtual Machine . I understand every full node in ethereum network will have its own "Ethereum Virtual Machine" embedded in it .(One Full ...

I am trying to setup eth-brownie to get a feel of the framework but face a couple of import-related problems. Im working from a MBP running macOS with Catalina v10.15.7 $ python --version Python 3.9.9 ...

Infura - free/paid Alchemy - free/paid Cloudflare-ETH - full free Can someone explain to me why all video tutorials dApp on youtube use Infura instead of completely free CloudFlare?

i am trying to do a call of a method to smart contract this is my attempt: response = contract.methods.updateState(address).send({ from: accounts[0] }) but i am getting this error: Gas limit must be ...

I want to transfer per second of given time but I got Error: Note: The called function should be payable if you send value and the value you send should be less than your current balance. pragma ...

I want to read all (!) historical price feed prices of a specific Chainlink price feed proxyContract off-chain via Javascript. Based on the docs article I iterate my query, each time reducing my ...

I'm trying to make sure I fully understand the behavior of try/catch, specifically what state gets reverted when we catch an error. I could not be sure of certain behavior from the v0.8.10 docs. If I ...

Looking at the direct swap example https://github.com/0xProject/0x-api-starter-guide-code/blob/master/src/direct-swap.js#L105-L113 Seems like the transaction is send to the chain's RPC URL which is ...

I'm trying to get the version to show up when I test it but keep receiving this message. call to FundMe.getVersion errored: VM execution error. Reverted 0x // SPDX-License-Identifier: MIT pragma ...

I struggled to find a nice solution to my question and thought of sharing it here so that others could benefit and others may have better suggestions. I have a solidity code where I have a function ...

In solidity 0.7 contract, an event tradeCompleted is defined as: event tradeCompleted(address _poster, string _posterItemName, uint256 _posterItemID, address _bidder, string _bidderItemName, ...

I would like to write a dapp that allows users to script transactions i.e. swap X for Y every 12 hours withdraw 5% from pool every day I thought about the following steps: The user defines the ...

I want to create a Coin Flip game on Ethereum blockchain. I have one contract called CoinFlip. It has functions that enables one player to make a bet, second player can accept the bet, then the flip ...

Say I have a GraphQL query like this, which I execute against a subgraph powered by The Graph: { foo { id bar } } What is the default number of instances of foo that a subgraph returns?